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Glacial Deposits, Northeastern Kansas

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County Studies, continued

Leavenworth County

Geology

The generalized geology of Leavenworth County has been mapped by Ward and O'Connor (1983) on a geologic map of the Topeka to Kansas City corridor (fig. 5). Rock formations exposed within the county range from the Wyandotte Limestone of the Kansas City Group (oldest) in an area adjacent to the Kansas River to the Deer Creek Limestone of the Shawnee Group (youngest) in northwestern Leavenworth County along Stranger Creek. The Wyandotte Limestone is the only formation of the Kansas City Group exposed in the county, and it is only poorly exposed in a few southeastern areas. The Lansing Group, exposed along the Missouri River, its western tributaries, and the eastern part of the Kansas River drainage area, includes 75 ft (23 m) of fossiliferous limestone and black, brown, and gray shales. The Douglas Group is the most widely exposed group in Leavenworth County. It occurs over a large area in the southwestern uplands surrounding Stranger and Ninemile creeks. Exposures are also present along stream valleys in the northeastern region of the county. The Douglas Group [240-400 ft (73-120 m) thick] is divided into two formations (Zeller, 1968): The Stranger Formation contains sandstone, shale, and a minor amount of limestone, coal, and conglomerate; the Lawrence Formation consists chiefly of gray shale and sandstone, which weathers yellowish-gray, and minor amounts of red shale, coal, gray limestone, and conglomerate. Rocks of the Shawnee Group that are exposed in the county include five formations: the Oread Limestone, the Kanwaka Shale, the Lecompton Limestone, the Tecumseh Shale, and the Deer Creek Limestone. The complete Shawnee Group is 325 ft (99 m) thick. It consists of escarpment-forming limestone, gray, tan, black, and red shales, local coal beds, and some cherty limestones. Exposures of the Shawnee Group are chiefly of the Kanwaka Shale and Oread Limestone. The Tecumseh Shale and the Lecompton Limestone are exposed along streams in northwestern Leavenworth County, and the Deer Creek Limestone has a few scattered exposures in extreme northwestern Leavenworth County.

Unconsolidated deposits in the county include glacial drift, loess, and alluvium (fig. 9). Glacial drift generally covers the upland regions of the county and sections along the Kansas River. Loess deposits occur mainly along the Missouri River bluffs and other scattered upland regions. Alluvial deposits are extensive and include alluvium of the bordering Missouri and Kansas rivers and of Stranger Creek, which cuts through the county in a north-south direction, flowing southward into the Kansas River.

The oldest Quaternary deposits in Leavenworth County are of "Kansan" age and include alluvial terraces and glacial drift deposits. Dissected remnants of outwash gravel, sand, and silt deposited during glacial retreat in pre-Illinoian time are preserved as the Menoken terrace along the Kansas River. Menoken terrace deposits are generally 80-100 ft (24-30 m) above the floodplain (Dufford, 1958) and are found along the Kansas River, except in areas where the river alluvium is adjacent to outcropping rock of the Pennsylvanian System. Glacial-drift deposits consist of a heterogeneous mixture of clay, silt, sand, gravel, and boulders deposited by glacial ice and meltwater and are of pre-Illinoian age. Glacial-drift deposits can reach 100 ft (30 m) in thickness in a buried valley area in Leavenworth County, and thicknesses on hilltops can reach 65 ft (20 m) (NE sec. 1, T. 9 S., R. 21 E.).

Illinoian time is represented by a few dissected remnants of the Buck Creek terrace, preserved along the Kansas River predominantly near the mouths of large tributary streams. The Buck Creek terrace consists of sand, sandy silt, and fine gravel grading upward into silt.

North of De Soto, Kansas (NE NE sec. 21, T. 12 S., R. 22 E.), there is an exposure of volcanic ash in the lower part of deposits mapped by Dufford (1958) as Menoken terrace deposits. O'Connor (1971) referred to these deposits as late Kansan because of the presence of Pearlette volcanic ash (Swineford, 1963). Geil (1987) has dated the ash as 0.58 ± 0.09 m.y. Given this age, the ash is interpreted by Geil as being the Lava Creek B (Pearlette O) ash K/Ar dated at 0.62 m.y. by Izett and Wilcox (1982). The terrace deposit mapped as Menoken would therefore be pre-Illinoian according to the prevailing Pleistocene glacial chronology (e.g., Hallberg, 1986).

Deposition during the late Wisconsin and the Holocene is represented by fill of the Newman and younger terraces and floodplain alluvium of the Kansas River. The lithology of the alluvium is similar and grades upward from locally derived limestone pebbles and boulders and arkosic sand and gravel to fine-grained sand, silt, and silty clay. The Newman terrace in Leavenworth County occurs mainly in association with streams draining to the Kansas River, including Wolf Creek, Kaw Creek, Stranger Creek, and Ninemile Creek. At the confluence of the Kansas and Wakarusa rivers, the valley width of the Kansas River is 5 mi (8 km), diminishing eastward to 1 mi (1.6 km) close to the Wyandotte County border.

During late Wisconsinan time (ca. 40-ka) and into the Holocene, loess accumulated on hills adjacent to the Missouri River valley and other scattered upland regions mainly in eastern Leavenworth County. Deposits can range from a few feet to 60 ft (18 m) thick and originated as windblown particles largely derived from floodplain silts of the Missouri River valley (Dort, 1972a).

The drainage systems of Leavenworth County were greatly influenced by Pleistocene glacial events. PrePleistocene drainage in the county may have been mainly in a southern direction into the Kansas River and probably included Stranger and Ninemile creeks. Dufford (1958) stated that these streams were misfits in their present regime, indicating that their meanders do not fit the size of the valley in which the modern stream flows. A period or periods of incision may have produced these effects. Incision might have resulted from isostatic uplift in front of the ice load, glacial rebound as the glacier retreated, the great amount of meltwater produced by the receding glacier, or intermittent seasonal melting.

The bedrock topographic map of Leavenworth County (plate 1) was prepared using 947 drill logs, as described by Denne et al. (1990a), the geologic map prepared by Ward and O'Connor (1983), and the metric surface topographic map (U.S. Geological Survey, 1981c). The data densities vary greatly in Leavenworth County, with the densest data located in the southeast, adjacent to Wyandotte County. The sources of these data are predominantly old (pre-1974) and new (1974 and later) water-well records for domestic wells.

Steep bedrock surface topography, discernible on the bedrock topographic map, reflects drainage incision processes, and topographically subdued areas are generally overlain by glacial drift. O'Connor and Fowler (1963) believed that this area had a much more subdued topography before glaciation.

A deep buried valley is located in T. 10 S., R. 22 E., and cuts in an east-west direction into Wyandotte County and eventually reaches the Missouri River valley. This buried channel is defined by depth to bedrock values of up to 105 ft (32.0 m) in sec. 15 and a gravel thicknesses of 69 ft (21 m) from a test hole in SW SW SE sec. 14, T. 10 S., R. 22 E. Depth to bedrock values and total sand and gravel thicknesses (figs. 53 and 54, respectively) support the existence of this buried channel.

Figure 53--Depth to bedrock, Leavenworth County.

Depth to bedrock, Leavenworth County.

Figure 54--Total Pleistocene sand and gravel thickness, Leavenworth County.

Total Pleistocene sand and gravel thickness, Leavenworth County.

The relationship of the buried channel to a constriction in the bedrock floor of Stranger Creek (southeast comer of T. 10 S., R. 21 E.) and a shallower buried channel trending north-south in T. 11 S., R. 22 E., may indicate a drainage pattern affected by channeling of meltwater around and away from an ice lobe in this area. The possible blockage of Stranger Creek by ice at this constriction may have caused ponding above the constricted area and subsequent diversion of its waters to the east and south along the buried channels. The greater sinuosity of Stranger Creek south of this constriction supports the location of an ice lobe in this area. The ice caused greater stream incision because of isostatic effects and the large amount of meltwater. The greater meandering south of the constriction also supports this conclusion. Schumm (1963) has suggested that greater meandering results when a large proportion of the load is carried as suspended load (mainly silt and clay).

The bedrock knob located in the southeastern portion of T. 11 S., R. 22 E., is associated with a large amount of sand and gravel [45 ft (14 m)] reported on its eastern side (NWNENW sec. 35, T. 11 S., R. 22 E.) according to test holes drilled by an engineering firm in 1983. This bedrock knob supports the theory that the shallow buried valley to the north was a short-term spillway that flowed around the resistant bedrock into small tributaries north of the Kansas River.

The general trend of the northern tributary to Little Stranger Creek is-north-south and may be an extension of the buried channel in T. 11 S., R. 22 E. This drainage system is parallel to the present Stranger Creek drainage and supports the spillway scenario. Four data points, located along the buried northern drainage, have sand and gravel thicknesses of 3-46 ft (0.9-14 m) and depth to bedrock values of 26-70 ft (7.9-21 m).

Another explanation for these drainage systems is the existence of an ice-marginal drainage along Stranger Creek, ending along the buried valley in T. 10 S., R. 22 E. Meltwaters might have flowed around the ice margin and southward and eastward from its southern extent. A large amount of sand and gravel to the east of Stranger Creek and in relation to the buried valley supports the existence of an ice margin here.

There are many Stranger Creek tributary valleys that contain a large amount of sand and gravel in their upper reaches. The presence of coarse-grained material in these regions probably results from glacial processes. Questionable sand and gravel thicknesses of 7-60 ft (2-18 m) and depth to bedrock values of 61-127 ft (19-38.6 m) in secs. 22 and 25, T. 9 S., R. 20 E., are found in an extension of the bedrock valley of a Fall Creek tributary. Sand and gravel thicknesses of 7-12 ft (2-3.7 m) occur in the region where Fall Creek joins Stranger Creek. These streams cut through thick glacial drift deposits in this area. Three data points along Ninemile Creek report sand and gravel thicknesses between 1 ft (0.3 m) and 17 ft (5.2 m) and depths to bedrock of up to 52 ft (16 m); Tonganoxie Creek has sand and gravel 4-15 ft (1-4.6 m) thick. A small tributary valley on the western side of Stranger Creek (SE SW SE sec. 2, T. 11 S., R. 21 E.) has a questionable sand and gravel thickness of 47 ft (14 m) and a depth to bedrock of 82 ft (25 m).

Up to 35 ft (11 m) of sand and gravel overlie an elevated bedrock area (NW SW NW sec. 6, T. 9 S., R. 22 E.; SE SW NE sec. 2, T. 9 S., R. 21 E.) that forms a divide between drainage to Stranger Creek on the west and drainage to the Missouri River on the east. Northward along this divide, sand and gravel deposits range from 1 ft to 35 ft (0.3-11 m) thick, and depth to bedrock values can reach 65 ft (20 m) (NE NE NE sec. 2, T. 9 S., R. 21 E.) along the uplands. A questionable data point (NW NW NW sec. 34, T. 9 S., R. 22 E.) indicates a depth to bedrock value greater than 104 ft (31.7 m) in an upland region at the head of southward drainage into Stranger Creek or into the buried-valley area. Sand and gravel thicknesses in this upland area are 8-25 ft (2-7.6 m).

The largest sand and gravel thicknesses are located in the Missouri and Kansas River alluvium; the thickness can reach 95 ft (29 m) [58 ft (18 m) of sand and 37 ft (11 m) of fine-grained sand] in the Kansas River alluvium (NW NE NW sec. 21, T. 12 S., R. 22 E.). The depth to bedrock values reach 99 ft (30 m) in the Missouri River alluvium deposits and 72 ft (22 m) in the Kansas River deposits. The Stranger Creek alluvium has sand and gravel thicknesses ranging from 2 ft to 29 ft (0.6-8.8 m). The depth to bedrock generally increases in a northerly direction from 36 ft to 62 ft (11-19 m) (NW NE NE sec. 19, T. 8 S., R. 21 E.) in the Stranger Creek deposits.

Ground Water

The alluvial deposits along the Missouri and Kansas rivers provide the greatest quantity of water to wells in Leavenworth County. Well yields are shown in fig. 55 and are given by Denne et al. (1990a). Wells can yield up to 5,000 gpm (0.3 m3/s) of water in the Missouri River alluvium (NW NE NE sec. 13, T. 8 S., R. 22 E.) and 2,000 gpm (0.1 m3/s) in the Kansas River alluvium (NW NW NE sec. 27, T. 12 S., R. 20 E.). Fader (1974) reported yields for the Kansas alluvium of 500-1,000 gpm (0.03-0.06 m3/s), depending on the saturated thickness of the deposits. The city of Leavenworth has seven public supply wells, yielding 2,000 gpm (0.1 m3/s) each, in the Missouri River alluvium (secs. 7 and 8, T. 9 S., R. 23 E.). Reported yields in the Stranger Creek alluvium where it joins the Kansas River alluvium are 50-150 gpm (0.003-0.0095 m3/s). Otherwise, the alluvium of Stranger Creek and its tributaries have yields of 10-50 gpm (0.0006-0.003 m3/s).

Figure 55--Estimated well yields, Leavenworth County.

Estimated well yields, Leavenworth County.

The buried-valley area in T. 10 S., R. 22 E., shows yields in the range 10-100 gpm (0.0006-0.006 m3/s) (fig. 55). Thirty-three domestic wells in this region have yields of 10-36 gpm (0.0006-0.0023 m3/s). Along the north-south-trending valley on the eastern side of the bedrock knob (NW NE NW sec. 35, T. 11 S., R. 22 E.), two engineering test holes were expected to yield 200 gpm (0.01 m3/s). Hilltop drift deposits generally yield 0-8 gpm (0-0.0005 m3/s) where they are saturated. In the region where Fall Creek cuts through glacial deposits, reported yields range from 7 gpm to 40 gpm (0.0004-0.003 m3/s) in 5 wells.

Sandstone bedrock of the Stranger Formation is an important aquifer for domestic wells in Leavenworth County. There are 84 bedrock wells located in T. 11 S., R. 21 and 22 E., and T. 12 S., R. 20 E., that have yields ranging from 10 gpm to 75 gpm (0.0006-0.0047 m3/s). these wells have a mean yield of 25 gpm (0.0016 m3/s) and a mean total depth of 130 ft (40 m). The initial bedrock type encountered in these wells is chiefly yellow, brown, or red sandstone or sandstone of undescribed color. There are also many bedrock wells that report yields of less than 1 gpm (0.00006 m3/s). The great density of wells in these areas of Leavenworth County is largely due to these bedrock wells.

The depth to water in Leavenworth County is greatest in bedrock wells. All depth to water values of 100 ft (30 m) or greater are from bedrock formations, except for one questionable value in sec. 35, T. 10 S., R. 21 E. There were four bedrock wells with water levels of 200 ft (60 m). Figure 56 indicates that most of the bedrock wells have water levels between 50 ft (15 m) and 100 ft (30 m).

Figure 56--Depth to water in wells and test wells, Leavenworth County.

Depth to water in wells and test wells, Leavenworth County.

Water levels in the Missouri River valley have a mean of 11 ft (3.4 m) below the land surface using eight data points. Water levels in the Kansas River valley have a mean of 22 ft (6.7 m) below the land surface using 33 data points, including five wells in terrace deposits with water levels between 30 ft (9 m) and 48 ft (15 m). There were only five points overlying the deepest part of the bedrock valley of Stranger Creek. Three data points north of the constricted area have depth to water values of 5, 5, and 6 ft (2 m), and two data points south of this area have depth to water values of 16 ft (4.9 m) and 23 ft (7.0 m). This may give clues to the depositional history of the Stranger Creek valley, although data from the Stranger alluvium are sparse at present.

The buried-valley region in T. 10 S., R. 22 E., has depth to water values of 18-90 ft (5.5-27 m) for 29 data points and a mean of 56 ft (17 m). There are four data points north of the deepest section of the buried valley with water levels of 80 ft (24 m) below the land surface, md two data points to the south reporting depth to water /alues of 90 ft (27 m). The depth to water values in glacial-drift deposits located in other areas of Leavenworth County are generally between 10 ft (3 m) and 30 ft (9 m). Water levels of 30 ft (9 m), 40 ft (12 m), 50 ft (15 m), and 59 ft (18 m) below the land surface (Denne et al., 1990a) are associated with the area where Fall Creek joins Stranger Creek.

Unconsolidated deposits in Leavenworth County have saturated thicknesses (fig. 57) of less than 100 ft (30 m), with a maximum value of 86 ft (26 m) from the Missouri River alluvium (sec. 13, T. 8 S., R. 22 E.). Saturated thicknesses in the Missouri River deposits range from 57 ft to 86 ft (17-26 m) compared to the Kansas River values, which range from 9 ft to 53 ft (3-16 m). The Stranger Creek valley has saturated thickness values of 46 ft (14 m) and 52 ft (16 m) in the vicinity of Wolf Creek.

Figure 57--Saturated thickness of Pleistocene deposits, Leavenworth County.

Saturated thickness of Pleistocene deposits, Leavenworth County.

The buried valley in T. 10 S., R. 22 E., contains saturated glacial materials 13-71 ft (4.0-22 m) in thickness, with 16 values greater than or equal to 30 ft (9 m). Saturated sections of unconsolidated materials are prominent in many areas adjacent to bedrock knobs (sec. 35, T. 11 S., R. 22 E.; sec. 3, T. 11 S., R. 21 E.; and secs. 9, 16, and 17, T. 10 S., R. 21 E.) and can be of the order of 20-30 ft (6-9 m) in thickness along other bedrock highs (e.g., data points in sec. 2, T. 9 S., R. 21 E., and sec. 27, T. 8 S., R. 21 E.).

There are many saturated thickness values for unconsolidated deposits of zero, reflecting the presence of bedrock wells in these areas. Unsaturated (no free water) materials are chiefly located in areas of bedrock highs and to some extent in the upper portions of stream valley bedrock walls.

The water table along the Kansas River generally declines from 791 ft (241 m) to 753 ft (230 m) as the river flows eastward. Water-table values of 744-768 ft (227-234 m) are reported in a 12-mi (19-km) reach of the Missouri River bordering Leavenworth County. Data along the Stranger Creek valley indicate water-table values of 870 ft (265 m) in the upper reaches, declining to 819 ft (250 m), 12 mi (19 km) to the south along its course (SW sec. 6, T. 11 S., R. 22 E.).

Some of the highest water-table values are present in hilltop-drift deposits in northwestern Leavenworth County. They range from 1,065 ft to 1,090 ft (324.6-332.2 m) in elevation. A hilltop area in T. 10 S., R. 20 E., also has many high water elevations in glacial-drift deposits, including nine data points ranging from 1,044 ft to 1,090 ft (318.2-332.2 m). The water table in the buried-valley region is generally at 900 ft (270 m), declining toward Stranger Creek to the west with values in the 800-ft (240-m) range.

Nemaha County

Geology

The geology of Nemaha County has been described by Mudge et al. (1959) and Ward (1974). The development of the Nemaha anticline and the Humboldt fault zone (see fig. 3) significantly influenced the distribution, thickness, and dip of the bedrock units in the county. Although glacial deposits cover most of the surface, some bedrock exposures occur along valleys in the northern half of the county and along the southwestern border. The oldest exposed rocks (from the Shawnee and Wabaunsee Groups of Pennsylvanian age) extend from north-central to southwestern Nemaha County (fig. 5). Permian rocks are exposed on both sides of the anticlinal structure. The total thickness of sedimentary rocks above the Precambrian basement ranges up to 1,000 ft (300 m) on the western flank of the anticline and to 4,000 ft (1200 m) on the eastern flank. Dips of bedrock units vary from 30° eastward in the Permian units on the downthrown (eastern) side of the fault near Bern to horizontal or slightly westward in the Pennsylvanian beds just west of the fault to 15 ft/mi (0.16°) westward in the western part of the county (Ward, 1974).

As described by Ward (1974) and Mudge et al. (1959), the Pennsylvanian rocks exposed in Nemaha County include shales and limestones with some sandstones and coal beds. The Topeka Limestone of the Shawnee Group is 20-30 ft (6-9 m) thick, and the formations in the Wabaunsee Group are 325-450 ft (99.1-137 m) thick. The Admire Group of Permian age contains 100 ft (30 m) of shale, limestone, and sandstone. The Council Grove Group is 239-310 ft (72.8-94.4 m) thick and is dominated by shales and limestones. Some of the limestones are cherty, whereas others contain gypsum or solution channels where gypsum has been dissolved. The cherty Wreford Limestone of the Chase Group is 30-40 ft (9-12 m) thick and is the youngest bedrock unit in the county.

Unconsolidated deposits cover most of Nemaha County. The oldest are pre-Illinoian tills, outwash, and glaciolacustrine sands and silts. In the buried valleys a basal limestone and chert gravel, generally less than 15 ft (4.6 m) thick, is overlain by up to 100 ft (30 m) of fine-grained to very fine grained silty sand (or, locally, sandy silt or clay) of the Atchison Formation (Ward, 1974). The Atchison Formation has been interpreted as glaciolacustrine, and Mudge et al. (1959, p. 211) noted that "bedding is apparent in all [glaciolacustrine] deposits, and iron stains are on the bedding planes." Overlying the older sediments in the buried valleys and occupying other areas in the county are heterogeneous mixtures of clay, silt, sand, and gravel, considered by Ward (1974) to be the Cedar Bluffs and Nickerson tills. The older (Nickerson) till ranges from 0 to 240 ft (73 m) in thickness, is generally gray, and contains fewer erratics than does the Cedar Bluffs Till, which is tan to brown to light gray and less than 100 ft (30 m) thick (Ward, 1974). Lenses of sand and gravel occur locally within each till, and a layer of outwash 0-50 ft (0-15 m) thick occurs between the two tills. Ward (1974, p. 9) believed that the Nickerson till "may not have been deposited on the highest bedrock surfaces" and that the "Cedar Bluffs Till is present throughout the county except along stream valleys where it has been removed by late Pleistocene erosion." Figure 58 shows the distribution of the pre-Cedar Bluffs Pleistocene units as mapped by Ward (1974). One peculiar feature of this map is that, if the buried valleys and basal gravel [shown as Nebraskan (?) deposits] are correctly mapped, then in the tributaries the coarse-grained material occurs only at the downstream ends. This still could be true if erosion removed the gravel upstream or if the gravel was deposited near an ice margin and/or by streams that had reversed drainage for some period of time.

Figure 58--Distribution of Pre-Cedar Bluffs Pleistocene units, Nemaha County. From Ward (1974, fig. 4).

Distribution of Pre-Cedar Bluffs Pleistocene units, Nemaha County.

The youngest deposits in Nemaha County are loess and alluvium; they have been described by Ward (1974) and Mudge et al. (1959). The Illinoian and Wisconsin loess deposits generally mantle the uplands with less than 10 ft (3 m) of silt. Terraces and alluvial deposits in stream valleys range from Illinoian to Holocene and generally consist of sandy clay (commonly reworked glacial deposits) with a sand and gravel layer at the base and/or locally within the deposit. The texture varies along different streams, however; for example, the Spring Creek alluvium is mainly fine-grained sand and silt (Mudge et al., 1959). In Nemaha County the older terraces and valley-fill deposits range up to 50 ft (15 m) in thickness, whereas the younger alluvial deposits are generally less than 30 ft (9 m) thick (Ward, 1974).

Using 582 drill-hole logs (Denne et al., 1990a) and maps of the surface topography [with contours at 50-ft intervals generalized from the U.S. Geological Survey (n.d.)] and bedrock geology (Ward, 1974), we constructed a bedrock topographic map of Nemaha County (plate 1). Several data problems (sparse availability of data in some areas, the difficulty in differentiating gray shales from gray glacial clays on some logs and in some boreholes, and the numerous water wells and test holes that did not even reach bedrock) limit the accuracy of the bedrock topographic map. To interpret channel locations between distant data points, we considered several factors: (1) valley width (because Recent stream valleys widen where they cross some buried valleys), (2) "gaps" in bedrock exposures along streams (because now-buried drainages would have eroded bedrock to a lower level), and (3) sand and gravel deposits. We also used total well depth and aquifer information from the U.S. Geological Survey historical water-quality file to estimate bedrock elevations when other data were unavailable.

In Nemaha County the main buried valley, which is a tributary of the ancestral Grand River in Missouri, has been recognized by Frye and Walters (1950), Frye and Leonard (1952), Dreeszen and Burchett (1971), and Ward (1974). In plate 1 the channel is clearly evident, extending from west to east in the southern part of Nemaha County. Data in the area common to T. 3 and 4 S., R. 13 and 14 E., suggest that the valley trends northeastward to the common corner of the townships and then bends to follow a southeastern course. There is a bedrock high to the south of the valley, but the structure may also contribute to the channel orientation.

In T. 4 S., R. 13 E., the buried valley is between faults, as mapped by Cole (1976) and DuBois (1978). The southeast-trending channel in T. 4 S., R. 14 E., is close to part of and coincident with the remainder of the fault that DuBois (1978) mapped in that township. The latter fault also underlies Wolfley Creek near the Jackson County border. In addition to fault control of valley locations, perhaps an ice lobe developed and later blocked a marginal drainage system.

The western part of the main buried valley (from the Marshall County line to the northeast comer of T. 4 S., R. 13 E.) corresponds closely to a LANDSAT tonal pattern, as described by Denne et al. (1982) and Denne, Yarger, et al. (1984). In this area the valley underlies a modern topographic high. The LANDSAT pattern continues along a probable bedrock high and a topographic high to the northwestern comer of T. 3 S., R. 14 E., where the pattern becomes indistinct. The lobate shape of the LANDSAT pattern and the topographic high of the land suggest that the pattern high indicates the remnants of an end moraine. To the north the feature may have been obliterated by another ice lobe extending southeastward along Gregg Creek (see the section on the geology of Brown County). If indeed an ice lobe blocked part of the major now-buried valley, drainage could have escaped southeastward through T. 4 S., R. 14 E.; T. 5 S., R. 13 E.; and T. 5 S., R. 12 E., in addition to other small valleys (see plate 1).

In Nemaha County the main buried channel may be as much as 3 mi (5 km) wide and 400 ft (120 m) deep from the land surface to the bedrock bottom of the channel. In southwestern Nemaha County (E-E' in plate 1 and fig. 59), test holes were drilled and geophysical techniques were used to evaluate the channel deposits (Denne et al., 1982, 1984). The surface topography and field data for the profile are shown in fig. 60. The outer limits of the valley system along this profile are defined at least by bedrock exposures at the south end (site J) and 1 mi (1.6 km) north of site A. Data from sites B and D indicate a steeply sloping northern valley wall. The deepest part of the channel occurs between sites D and E, and these test holes contain 8-19 ft (2-5.8 m) of basal gravel and sand. Test hole F, with 8 ft (2 m) of basal sand and gravel, appears to be on the gently sloping southern side of the valley, as is site G, which has 149 ft (45.4 m) of silty and fine-grained sandy glaciofluvial material overlain by 52 ft (16 m) of till.

Figure 59--Location of buried valley in Nemaha County.

Location of buried valley in Nemaha County.

Figure 60--Surface topography and field data for cross section E-E', Nemaha County. Location of section shown in plate 1 and fig. 59.

Surface topography and field data for cross section E-E', Nemaha County.

Although the main buried valley is fairly well defined, the extent and orientation of the numerous tributaries are difficult to determine from the available data. Nevertheless, it appears that a significant channel drained generally southeastward around some bedrock "islands" to the southeastern part of T. 3 S., R. 13 E. (plate 1). The South Fork Big Nemaha River is broad and lacks bedrock exposures where it apparently crosses the buried drainage (e.g., secs. 14, 23, and 35, T. 2 S., R. 12 E.). The circular shape formed by Turkey Creek and the South Fork Big Nemaha River may reflect structural control and/or ice-marginal drainage, and these valleys and their modern tributaries may be at least partly connected to the buried-channel system. A deep buried valley under the town of Bern (sec. 16, T. 1 S., R. 13 E.) and used for the public water supply is difficult to trace, but it may extend southwestward to Deer Creek and then either southeastward or westward to the South Fork Big Nemaha River.

It is interesting to note that Frye and Leonard (1952) showed a major drainage flowing from north to south slightly west of the center of the county during Wisconsinan time. This stream could have followed the course of the South Fork Big Nemaha River and Illinois Creek (both reversed with respect to their present flow directions) and then crossed the modern divide to the Red Vermillion Creek. Southward flow of the South Fork Big Nemaha River could explain the peculiar entrance angles for tributaries such as Deer, Wildcat, and Fisher creeks, although the buried valleys that cross below them may also influence their orientation.

Test holes drilled near Centralia and logs from more isolated areas in western Nemaha County suggest the presence of several narrow tributaries that drained southward to the major east-west buried valley (plate 1). Water wells and test holes in the vicinity of Woodlawn also indicate a deep valley, and core samples from NE NW NE sec. 16, T. 3 S., R. 14 E., show much waterdeposited material filling the channel there [for additional information, see the discussion of core W in Denne et al. (1984)]. Another buried tributary appears to have flowed southward across Deer and Harris creeks to the previously described intersection of T. 3 and 4 S., R. 13 and 14 E. If the location and orientation have been correctly interpreted, that valley is close to faults mapped by Cole (1976) and DuBois (1978).

The relationship between structure and geomorphology in Nemaha County should be studied in more detail because it may reveal significant clues to understanding both modern and buried drainages. Several possible correlations have already been discussed. In addition, recent microearthquakes suggest that the Humboldt fault zone is still active (Steeples et al., 1979), and a lineament formed by Negro Creek and the upper reaches of the North Fork Black Vermillion River may be the result of recent movements in glacial deposits (DuBois, 1978). Especially on the west side of the Humboldt fault (where the sedimentary rock sequence is relatively thin), DuBois (1978) believed that the structure exerted considerable control on drainage.

In Nemaha County the depth to bedrock (fig. 61) ranges up to 400 ft (120 m) (NW NW NW sec. 28, T. 4 S., R. 13 E.). Values exceeding 300 ft (90 m) are common in the main buried valley, especially at and on the western side of the sharp bend in the valley (northeastern comer of T. 4 S., R. 13 E.). Toward the southeast from the bend, near the modern Wolfley Creek, the depth to bedrock in the buried valley is generally within the range of 150-250 ft (46-76 m). A buried tributary that underlies part of Spring Creek has 100-200 ft (30-60 m) of alluvial and glacial deposits. Several other southern tributaries to the main buried channel (e.g., in T. 5 S., R. 13 E., and T. 5 S., R. 12 E.) contain deposits thicker than 100 ft (30 m).

Figure 61--Depth to bedrock, Nemaha County.

Depth to bedrock, Nemaha County.

The buried valley that extends northeastward through T. 3 S., R. 14 E., into T. 2 S., R. 14 E., contains up to 310 ft (94 m) of sediments in the area near Woodlawn. If mapped correctly, the tributary that trends northward from the sharp bend in the main channel contains 37-368 ft (11-112 m) of unconsolidated material, with the smallest amounts underlying the modern Deer Creek. The depth to bedrock is difficult to determine in test holes in SW SW SW sec. 23, T. 3 S., R. 13 E., and NW NE NW sec. 14, T. 3 S., R. 13 E., but it appears to be 368 ft (112 m) and 255 ft (77.7 m), respectively. The former test hole would then be in a deep part of the channel [bedrock elevation of 952 ft (290 m)], and the latter, which has more sand and gravel and a 1,090-ft (332.2-m) bedrock elevation, would be on the valley wall. These two test holes are also significant because the 1979 gamma, self-potential, and resistivity logs are almost identical for depths below 370 ft (110 m) in sec. 23 and below 285 ft (86.9 m) in sec. 14. If we assume that there is stratigraphic equivalence and no dip, then there would be a 110-ft (34-m) offset between bedrock units at these sites, which are only 2 mi (3 km) apart. Seismic work (Steeples, 1981, figs. 8-12) indicates that one of the test holes (SW SW SW sec. 23, T. 3 S., R. 13 E.) is in a graben, whereas the test hole in NW NE NW sec. 14, T. 3 S., R. 13 E., is on the upthrown side of the northernmost of the two faults bounding the graben. If the graben controlled the location of the now-buried drainage, a valley may have extended northeastward from the test hole in sec. 23, T. 3 S., R. 13 E., toward SW sec. 7, T. 3 S ., R. 14 E. (across the bedrock high as now mapped).

Other significant thicknesses of glacial deposits occur in the northern tributaries to the main channel (e.g., in the southwestern part of T. 3 S., R. 13 E., the southeastern part of T. 3 S., R. 12 E., most of T. 4 S., R. 12 E., and the eastern edge of T. 4 S., R. 11 E.). Northward extensions of these valleys also contain up to 180 ft (55 m) of sediments. The buried channel underlying Bern is at least 120 ft (37 m) deep. In general, however, the glacial cover is much thinner in the northern half of the county than in the southern half.

The total thickness of sand and gravel in Nemaha County (fig. 62) is greatest in the buried valleys. The largest values [207-264 ft (63.1-80.5 m)] occur in SW NW sec. 25, T. 3 S., R. 13 E., NE NE NW sec. 11, T. 4 S., R. 13 E., SE NE SE sec. 3, T. 5 S., R. 11 E., and SE NE NE sec. 10, T. 5 S., R. 11 E. [see Denne et al. (1990a)]. These sites generally contain clay with layers of fine-grained sand beginning relatively near the land surface, fine- to coarse-grained sand at greater depths, and sand and gravel at or near the bedrock surface. In places the fine-grained sand [which ranges up to 200 ft (60 m) in thickness] may actually be dominated by and is sometimes logged as silt; thus some differences in total sand and gravel thickness may be the result of field estimation of grain size by various individuals. However, the sequence of sediments often does vary greatly within short distances, making test drilling important in evaluating the aquifer in an area and in optimizing selection of a well site. For example, test holes in sec. 32, T. 4 S., R. 11 E., had 0-18 ft (0-5.5 m) of basal gravel, and the driller estimated that a well in SE sec. 32 could yield 900 gpm (0.06 m3/s) (personal communication from the landowner, 1981).

Figure 62--Total Pleistocene sand and gravel thickness, Nemaha County.

Total Pleistocene sand and gravel thickness, Nemaha County.

A detailed analysis of the sand and gravel layers would help to determine the drainage history of Nemaha County. Some areas (e.g., in T. 3 S., R. 13 and 14 E., and T. 5 S., R. 14 E.) have sand and gravel deposits relatively high in the sediment column. These coarse-grained materials may be outwash or buried-channel deposits from a later episode and possibly a different orientation from that responsible for the basal sand and/or gravel layers that locally underlie them.

In the relatively recent alluvial deposits, sand and gravel layers are 0-15 ft (0-4.6 m) thick. The coarse material is generally at or near the bedrock surface. Where modern streams cross or are coincident with buried valleys, the total thickness of sand and gravel may be much greater than 15 ft (4.6 m) (e.g., parts of Tennessee and Harris creeks and South Fork Big Nemaha River near Seneca, Spring Creek, and Wolfley Creek). The oil logs along Gregg Creek (part of the lobate drainage system in Brown County) indicate 45 ft (14 m) of sand in NE NE SE sec. 28, T. 2 S., R. 14 E., and 35 ft (11 m) of "surface boulders." Throughout most of Nemaha County (except for the northeastern-most township), sand and gravel deposits can be found at least locally in the alluvial and glacial deposits. The coarse-grained materials are generally good sources of ground water. Where wells are sited in areas with fine-grained sand and silt, however, they must be carefully constructed and developed to prevent clogging of well screens or pumping of excessive sediment with the water.

Ground water

In Nemaha County wells in the glaciofluvial deposits may yield up to 900 gpm (0.06 m3/s) (estimate for test hole in SE sec. 32, T. 4 S., R. 11 E.), but generally they produce 200 gpm (0.01 m3/s) or less. Reported yields, which have not been corrected for well diameter or other variables, are shown in fig. 63. They are greatest in the main buried valley and in the channel deposits underlying the South Fork Big Nemaha River near Seneca (SW NW SW sec. 26, T. 2 S., R. 12 E.). Yields from the smaller buried tributary valleys are commonly less than 100 gpm (0.006 m3/s). Elsewhere, glacial deposits (especially the sand and gravel layers in them) may provide small amounts of water. Alluvial deposits along modern rivers yield 0-30 gpm (0-0.002 m3/s) (or more, where they overlie glacial buried valleys).

Figure 63--Estimated well yields, Nemaha County.

Estimated well yields, Nemaha County.

As previously discussed in the geology section, the Quaternary deposits vary both vertically and laterally; therefore a detailed test-drilling program should be done before large-capacity wells are constructed. In general, the coarsest and most permeable deposits are the basal gravels (such as those in SE sec. 32, T. 4 S., R. 11 E.). Ward (1974) gave estimated yields and specific-capacity values for the different aquifers of less than 200 gpm (0.01 m3/s) and 15-20 gpm/ft (0.0031-0.0041 m2/s) drawdown for the basal gravels, 10-100 gpm (0.0006-0.006 m3/s) and less than 2 gpm/ft (0.0004 m2/s) drawdown for the Atchison Formation, 50-200 gpm (0.003-0.01 m3/s) and 5-10 gpm/ft (0.001-0.002 m2/s) drawdown from outwash deposits between the two tills, and commonly less than 10 gpm (0.0006 m3/s) and 2 gpm/ft (0.0004 m2/s) drawdown for terrace and alluvial deposits. The Nickerson and Cedar Bluffs tills are relatively impermeable and do not yield much water where they are thin (especially near streams and bedrock highs), but local sand and gravel lenses may yield up to 10 gpm (0.0006 m3/s) where they are large enough and/or receive adequate recharge (Ward, 1974).

Bedrock units in Nemaha County yield 0-100 gpm (0-0.006 m3/s) of water. The highest yields are from the Council Grove Group of Permian age in the northeastern (e.g., secs. 1, 8, 16, and 36, T. 1 S., R. 14 E., and secs. 13 and 14, T. 2 S., R. 14 E.) and in south-central (e.g., NE SW SE sec. 15, T. 5 S., R. 13 E.) parts of the county. Unfortunately, bedrock units that yield the largest quantities generally have the poorest water quality. Sulfate levels are particularly high where gypsum layers in the limestone and shales have been dissolved.

The bedrock aquifers have been described by Ward (1974). The Pennsylvanian rocks are not generally aquifers, except for sandstone lenses in the Scranton Shale, which yield up to 10 gpm (0.0006 m3/s), and in the Willard, Pillsbury, and Root Shales and the Wood Siding Formation, which yield less than 5 gpm (0.0003 m3/s) to wells. Small quantities [<1 gpm (<0.00006 m3/s)] can be obtained from weathered and fractured zones of some other Pennsylvanian formations near their outcrop areas. In contrast, the Foraker and Grenola Limestones of Permian age yield as much as 50 gpm (0.003 m3/s), and the Red Eagle, Beattie, and Wreford Limestones may yield 10 gpm (0.0006 m3/s) to wells. Solution channels and fractures are important for water occurrence in these limestones. Sandstone lenses in the Janesville Shale of Permian age locally yield less than 5 gpm (0.0003 m3/s).

The depth to water levels are reported by Denne et al. (l990a). No attempt was made to contour water-elevation data because many values represent multiple aquifers and because the potentiometric surface is not continuous throughout the county. It is evident, however, that the elevations of water decline along the main buried valley from 1,200 ft (365 m) in the west to 1,050 ft (320 m) near the Jackson County border on the east.

The depths to water (fig. 64) are also of limited usefulness because of their composite nature. Head differences between various aquifers may be significant, as demonstrated by a nest of three piezometers installed in SW SW NW sec. 32, T. 4 S., R. 11 E., where water levels on August 2, 1983, were 144 ft (43.9 m), 136 ft (41.5 m), and 8 ft (2.4 m) for wells completed in the basal gravel at 350 ft (110 m), the intermediate fine-grained sand at 180 ft (55 m), and the uppermost glacial till at 80 ft (24 m), respectively. The clayey sediments isolate the aquifers, but the use of a continuous gravel pack along wells penetrating multiple aquifers allows interconnection of the aquifers.

Figure 64--Depth to water in wells and test wells, Nemaha County.

Depth to water in wells and test wells, Nemaha County.

Despite the complications in interpretation of the data, the greatest depths to water (when water was encountered in a drill hole) were reported to be 186 ft (56.7 m) and 172 ft (52.4 m) in the main buried valley in NW SE NE and NE SE NE sec. 2, T. 4 S., R. 13 E. Other large depths [up to 150 ft (46 m)] occur in bedrock wells in northeastern Nemaha County. A rather anomalously deep value [138 ft (42.1 m)] was also reported for the buried channel in SE NE SE sec. 20, T. 2 S., R. 12 E., but the elevation [1,087 ft (331.3 m)] is comparable to others in the South Fork Big Nemaha River modern and buried drainage system. Although the depths to water in the glacial and bedrock aquifers vary considerably, values are commonly between 5 ft (2 m) and 25 ft (8 m) in the alluvial deposits.

In some wells in Nemaha County, water rises above the land surface. Ward (1974) mapped several areas of artesian flow near Gregg and Muddy creeks in T. 3 S., R. 14 E., and Coal Creek in T. 5 S., R. 12 E. Each of these areas has alluvial and/or glacial deposits. In his report Ward (1974) cited a few flowing wells from Permian limestones and at least one from the Atchison Formation or older glaciofluvial deposits.

Because the depth to water is used to calculate saturated thickness (fig. 65), the saturated-thickness values must be viewed with some caution. In addition, it should be recognized that a large saturated thickness does not necessarily include much good aquifer material. To choose a location for a large-capacity well, therefore, both saturated thickness and the presence of permeable sand and gravel deposits should be considered.

Figure 65--Saturated thickness of Pleistocene deposits, Nemaha County.

Saturated thickness of Pleistocene deposits, Nemaha County.

In Nemaha County the greatest saturated thicknesses occur in the main buried valley and its tributaries (fig. 59). The largest value [358 ft (109 m)] occurs at two sites where significant differences can be observed: in SW SW SW sec. 23, T. 3 S., R. 13 E., the dominant material is clay with sand and gravel between the depths 110 ft (34 m) and 120 ft (37 m), whereas in NE NE SE sec. 33, T. 4 S., R. 12 E., three layers of gravel total 22 ft (6.7 m) and fine-grained sand makes up 72 ft (22 m) of the sediment column.

The saturated thickness of alluvial deposits is commonly within the range 0-30 ft (0-9 m). As Ward (1974) observed, the smallest saturated thicknesses of glacial deposits generally occur near the walls of the modern valleys and over bedrock highs, but where 20-30 ft (6-9 m) of saturated thickness occurs, thin sand and gravel layers should still provide an adequate supply of water for domestic use.

In Nemaha County ground-water discharge is primarily to streams, springs, and wells. Recharge may be considerably more complicated. The topographic relief and the permeability of the exposed geologic units influence recharge directly from precipitation. Leakage between the unconsolidated aquifers and the bedrock aquifers (upward or downward, depending on the head relationships) also contributes to recharge. Little is currently known about the head differences between the various Quaternary, Permian, and Pennsylvanian aquifers, but Ward (1974, p. 11) stated that "where water moves from the Permian aquifers into glacial deposits within buried valleys, the hydrostatic level in the glacial deposits appears to equalize with that in the bedrock formation." Additional research is needed on this topic because it is important to the understanding of both the quantity and quality of water available.

Shawnee County

Geology

The geology of Shawnee County has been described by Johnson and Adkison (1967) and Johnson and Wagner (1967). The area is in the western part of the Forest City basin, a predominantly post-Mississippian structure. Exposed rocks strike 15°-30° and dip northwest at 15-40 ft/mi (2.8-7.6 m/km). The regional dip is interrupted locally by minor folds. The total thickness of unexposed sedimentary rocks, which range in age from Late Cambrian to Late Pennsylvanian, may be as much as 3,300 ft (1,000 m). Exposed sedimentary rocks include more than 1,000 ft (300 m) of the Shawnee and Wabaunsee Groups of Late Pennsylvanian age and the Admire and Council Grove Groups of Early Permian age (fig. 5). Formations of the Shawnee Group exposed in eastern Shawnee County include, in ascending order, the Oread Limestone, the Kanwaka Shale, the Lecompton Limestone, the Tecumseh Shale, the Deer Creek Limestone, the Calhoun Shale, and the Topeka Limestone. The Severy Shale, Howard Limestone, Scranton Shale, Bern Limestone, Auburn Shale, Emporia Limestone, Willard Shale, Zeandale Limestone, Pillsbury Shale, Stotler Limestone, Root Shale, and Wood Siding Formation make up the Wabaunsee Group. In western Shawnee County the Admire Group includes the Onaga Shale, the Falls City Limestone, and the Janesville Shale, and the Council Grove Group is represented by the Foraker Limestone and the Johnson Shale.

The stratigraphic sequence in Shawnee County includes cyclic deposits of shale, siltstone, sandstone, and limestone (Johnson and Adkison, 1967; Johnson and Wagner, 1967). Coal and conglomerate occur locally. In several areas large thicknesses of strata were eroded from channels, and sandstones filling the channels are part of the Calhoun, Severy, Scranton, Onaga, and Janesville Shales and the Wood Siding Formation. The Oread, Topeka, and Foraker Limestones contain some chert; the Howard Limestone locally includes gypsum; and several formations have inclusions of barite and/or celestite. Iron (limonite or pyrite) occurs in most formations. The rock units are gray, brown, black, orange, olive, yellow, red, or white. Where exposed, most of the formations are jointed, and the orientations of the two major sets of vertical joints are 60°-70° and 20°-30° (Johnson and Wagner, 1967).

Overlying bedrock in some parts of Shawnee County are colluvium, chert gravel deposits, till, outwash, loess, and alluvium (fig. 9). These materials have been described by Johnson and Adkison (1967) and Johnson and Wagner (1967). The colluvium consists primarily of clay, silt, and very fine grained sand. The deposits are thin and occur throughout much of the area, including the back side of stream terraces.

Remnants of late Tertiary or early Quaternary chert gravel deposits have been described at 10 upland sites in Shawnee County (Johnson and Adkison, 1967; Johnson and Wagner, 1967). The chert gravel also commonly contains limestone gravel, may be in a matrix of clay, silt, or sand, and is locally cemented. The chert was derived from the west, especially from the Wreford and Barneston Limestones of Early Permian age. It was deposited in the late Tertiary or early Quaternary valleys of the Kansas and Wakarusa rivers and a few tributaries, but subsequent erosion left some of the deposits high above the modern floodplains. A deposit northwest of Silver Lake, for example, overlies bedrock more than 150 ft (46 m) above the Kansas River floodplain (Davis and Carlson, 1952). When the county was glaciated, some of the chert gravel was incorporated into till and outwash deposits.

Johnson and Adkison (1967) and Johnson and Wagner (1967) mapped both glacial till and outwash as one unit. However, locally the till deposits are interbedded with outwash. The till is generally unstratified and consists of unsorted clay with silt, sand, gravel, cobbles, and boulders. Most of the gravel and larger fraction consists of limestone, igneous and metamorphic rocks, chert, sandstone, ironstone, quartz, and shale. The weathered till is light brown or reddish brown, and the unweathered till is gray. Where deeply weathered, the fine-grained material has been removed, leaving a concentration of gravel- to boulder-size material. The largest boulder reported in the area (Davis and Carlson, 1952) is in sec. 19, T. 10 S., R. 16 E., between Halfday and Indian creeks. This pink conglomeratic quartzite boulder consists of two pieces whose above-ground dimensions are 23 x 11 x 8 ft and 18 x 7 x 2 ft (7.0 x 3.4 x 2.4 m and 5.5 x 2.1 x 0.6 m).

Glacial outwash occurs primarily near the Kansas River and in the terminal area of the ice advance. The outwash, as described by Johnson and Adkison (1967) and Johnson and Wagner (1967), includes stratified clay, silt, sand, gravel, cobbles, and boulders deposited by meltwater during the advance (Atchison Formation) and retreat (Grand Island and Sappa Formations) of the Kansan ice sheet. The use of these three formation terms in Shawnee County is now rare. Johnson and Adkison (1967) and Johnson and Wagner (1967) stated that the formations were difficult to differentiate, but their Atchison Formation was commonly gravel and sand, sometimes overlain by silt. Their Grand Island Formation commonly included gravel and sand; and their Sappa Formation consisted primarily of glaciofluvial and glaciolacustrine silt. The outwash deposits range from well to poorly sorted, and some are cross bedded or have structures indicating deposition in a delta. Within the county the gravel ranges from deposits dominated by local rock types (e.g., limestone and chert with some shale and sandstone) to those with an abundance of erratics. The coarse-grained sediments are commonly subrounded to subangular. Some of the deposits are cemented by calcite. The Menoken terrace and Meade formation, as described by Beck (1959) and Davis and Carlson (1952), include the classical Kansan Stage Grand Island and Sappa Formations, but these three formation names are not now used in northeastern Kansas. The Menoken terrace was named by Davis and Carlson (1952, p. 212) "from the township [northwest of Topeka] where it is typically developed."

Although loess occurs on stream divides in Shawnee County, it is thin and poorly exposed and was not mapped by Johnson and Adkison (1967) and Johnson and Wagner (1967). Mudge and Burton (1959) described two exposures of Peoria (Wisconsin) loess just to the west of the Shawnee County border in Wabaunsee County. The material is typically tannish-gray to gray, locally iron-stained clay and silt that is leached of calcium carbonate in the upper part. The Illinoian Loveland loess and the Sangamon Soil also occur in Shawnee County.

In Shawnee County remnants of the Illinoian Buck Creek terrace (which is commonly covered and obscured by colluvium and loess) have been described and mapped by Johnson and Adkison (1967), Johnson and Wagner (1967), Beck (1959), and Davis and Carlson (1952). In the Kansas River valley, the Buck Creek terrace is generally less than 0.25 mi (0.4 km) wide and is 30-80 ft (9-24 m) above the river. Near the western border of the county, one test hole (NE NE NE sec. 19, T. 10 S., R. 13 E.) in the terrace deposits showed a 15-ft (4.6-m) basal layer of silty clay overlain by 14 ft (4.3 m) of clayey sand and gravel below 20 ft (6.1 m) of pebbly clay, silty clay, sandy silt, silt, and clay [the upper 15 ft (4.6 m) of which may be colluvium]. Near the eastern border of the county (north of Tecumseh), an exposure of the Buck Creek terrace includes at least 12 ft (3.7 m) of gravel below 10 ft (3.0 m) of silt with the Sangamon soil below loess. In the Wakarusa River valley, the Buck Creek terrace ranges up to 0.5 mi (0.8 km) in width, is generally 5-10 ft (2-3 m) above the adjacent Newman terrace, and consists of reddish-brown clayey silt with some pebbles, including chert and quartzite. On the west side of Cross Creek, the Buck Creek terrace is 20-90 ft (6-27 m) above the stream and almost 1 mi (1.6 km) wide. Along Mission Creek the height range is 15-45 ft (4.6-14 m) above stream level, and the width is generally less than 0.5 mi (0.8 km).

The Newman terrace occurs in the Kansas and Wakarusa River valleys and major tributaries in Shawnee County and has been mapped and described by Johnson and Adkison (1967), Johnson and Wagner (1967), Beck (1959), and Davis and Carlson (1952). In the Kansas River valley, the terrace is 20-45 ft (6-14 m) above the river, averages 1 mi (1.6 km) in width [although it ranges from 100 ft (30 m) to 2 mi (3 km)], and is best preserved on the northern side of the river, except near Topeka where the Shunganunga Creek enters the valley. In the Kansas River valley the Newman terrace fill, which ranges up to 90 ft (27 m) in thickness, includes a basal layer of coarse-grained sand, gravel, and cobbles overlain by clay, silt, and fine-grained sand. The material in the upper part is similar to sediments now carried by the river. The Newman terrace makes up most of the floodplain of the Wakarusa River and major creeks in the county.

Post-Newman (middle and late Holocene) alluvial deposits in Shawnee County also have been mapped and described by Johnson and Adkison (1967), Johnson and Wagner (1967), Beck (1959), and Davis and Carlson (1952). Along the Kansas River the alluvium ranges from 0.75 mi to 3.5 mi (1.2-5.6 km) in width, and together with the Newman terrace it forms the floodplain. The alluvial deposits include silt and silty clay over fine- to coarse-grained sand, which continues to grade downward to gravel and some boulders. There are some clay lenses, particularly in meander scars. Along the major tributaries of the Kansas River alluvial deposits are narrow [e.g., <150 ft (<46 m) wide along the Wakarusa River], and the scarp to the Newman terrace is commonly less than 5 ft (2 m) high.

In Shawnee County the southern bank of the Kansas River valley is generally steep, and the river currently flows along the southern side of the valley except where the Shunganunga Creek enters it in Topeka. As Davis and Carlson (1952, p. 215-216) noted, tributaries on the northern side of the Kansas River "are larger and more numerous. Thus the sediment supply from northern tributaries is much greater and produces a delta effect in the Kansas River channel which forces the river to the south. It is significant that the river shifts to the northern bluff line only opposite points at which large northwardflowing tributaries enter the channel." Somewhat in conflict with this idea is the Mission Creek entrance, where the Kansas River flows across the mouth of its valley. Perhaps the upstream junctions of the Kansas River with Cross Creek and several small tributaries on the north outweigh the influence of Mission Creek.

The southern limit of glaciation in Kansas extends east-west across Shawnee County, although its exact position is unknown (see fig. 7). The state geologic map (Kansas Geological Survey, 1992) indicates the position of the limit to be approximately halfway between the Kansas and Wakarusa rivers. Johnson and Adkison (1967) believed that the southern extent of ice in eastern Shawnee County was at the Wakarusa River but that it may not have gone over the east-facing escarpment formed by the Bern Limestone in the central part of the county. They suggested that the ice front extended northwestward along Lynn Creek from its junction with the Wakarusa River toward the town of Pauline to the Shunganunga Creek. Smyth (1898) described the terminal moraine buried in the Shunganunga valley. Farther west, Johnson and Wagner (1967) suggested that ice movement was limited by the divide between the Kansas and Wakarusa rivers and extended generally westward from the Shunganunga Creek and then southwestward along Mission Creek to the border with Wabaunsee County at about the position where Mission Creek bends to the south.

That the glacial limit may have been somewhat farther south than the area described by Johnson and Adkison (1967) and Johnson and Wagner (1967) is suggested by some well logs [e.g., SW SW SW sec. 16, T. 12 S., R. 15 E., where 55 ft (17 m) of glacial deposits were reported; NE NE SW sec. 28, T. 12 S., R. 14 E., which includes glacial clay and boulders from 17 ft to 28 ft (5.2-8.5 m); NW NW NE sec. 24, T. 13 S., R. 14 E., where brown clay with sand and/or gravel was encountered from 2 ft to 30 ft (0.6-9 m); and SE NE NW sec. 26, T. 13 S., R. 15 E., with 25 ft (7.6 m) of clay to sandy clay; all these sites, incidentally, are in areas mapped by previous investigations as bedrock]. Exposures near Auburn, such as in SW SE SE sec. 24, T. 13 S., R. 14 E., and NW NE NW sec. 29, T. 13 S., R. 15 E., also should be evaluated to determine whether the pebbly to bouldery clay, which includes both local and erratic rock types (chert, brown quartzite, and greenstone), is glacial till or outwash. Exposures of deposits that are more obviously outwash are known to occur nearby in the North Branch Wakarusa River valley and are described later.

Three miles (5 km) north of the glacial limit at the border between Shawnee and Wabaunsee counties [as mapped by Johnson and Wagner (1967)], a small preglacial valley was cut into Pennsylvanian shales. This channel (secs. 10 and 11, T. 12 S., R. 13 E.) is filled with ice-contact deposits of poorly stratified sand, gravel, cobbles, and boulders of the Atchison Formation(?) and glacial till (Johnson and Wagner, 1967; Mudge and Burton, 1959). Elsewhere in the county, glaciation had a more profound effect on the drainage system.

In early Pleistocene time the main drainage was probably to the east, approximately as it is now. When ice covered the area during pre-Illinoian time, many temporary drainage changes occurred. When the Kansas River was dammed by ice at St. George in Pottawatomie County (Smyth, 1898; Mudge, 1955; Mudge and Burton, 1959; Dort, 1987a), flow was diverted southeastward across northern Wabaunsee County to the present junction of Mill and Dry creeks near Maple Hill and then along Dry Creek. Water ponded in that area to an elevation of 1,115 ft (339.9 m) and then spilled southeastward across the divide between Dry and Mission creeks into Shawnee County (Mudge, 1955). Below its junction with the recent Haskell Creek, the Mission Creek valley (which together with Dry Creek forms a lobate shape) was also blocked by ice. Water beyond the ice ponded and then spilled over the divide southeastward into the North Branch Wakarusa River west of Auburn (Todd, 1911; Johnson and Wagner, 1967). Evidence for drainage along the North Branch includes outwash remnants (lag concentration of gravelto boulder-size limestone and glacial erratics plus a few small sand and gravel deposits). Most of the erratics occur 5-60 ft (2-18 m) above the stream on the east side of the Valley. Beyond the North Branch water flowed through the Wakarusa River to the Kansas River east of Lawrence in Douglas County (Todd, 1911; Johnson and Adkison, 1967; Johnson and Wagner, 1967). In addition to flow along the Wakarusa system, water also may have drained eastward from Mission Creek to Shunganunga Creek (Johnson and Wagner, 1967).

As ice blocked the major drainageways, several other temporary diversion channels were developed. Johnson and Wagner (1967) described a channel extending from sec. 29, T. 11 S., R. 15 E., southward to the Shunganunga Creek in sec. 16, T. 12 S., R. 15 E. A northflowing tributary to the Kansas River now occupies a broad [locally almost 1 mi (1.6 km) wide] valley in the northern half of this former diversion channel. In the southern half a recently acquired water-well record for SW sec. 4, T. 12 S., R. 15 E. (not field checked for location) indicates that the depth to bedrock is greater than 37 ft (11 m), the thickness of fine- to medium-grained sand is greater than 23 ft (7.0 m), and the yield is 40 gpm (0.003 m3/s). As the glacier retreated north of the Kansas River valley, it provided a large amount of outwash to the valley, and several other diversion channels developed. As described by Johnson and Wagner (1967), these include possible channels that flowed westward across the divide between Cross and Soldier creeks in the northern halves of sec. 1, T. 10 S., R. 13 E., and sec. 6, T. 10 S., R. 14 E., and southeastward near the common comers of secs. 1 and 12, T. 10 S., R. 13 E., and secs. 6 and 7, T. 10 S., R. 14 E. In NW sec. 33, T. 10 S., R. 15 E., meltwater may have temporarily drained eastward. Little Soldier Creek formerly flowed through the eastern half of sec. 18 and NW sec. 19, T. 10 S., R. 15 E. An exposure of sediments in SW NE sec. 18, T. 10 S., R. 15 E., includes 17 ft (5.2 m) of somewhat cemented gravel that seems to dip southwest and overlies bedrock.

A bedrock topographic map of Shawnee County (plate 1) was constructed using 436 logs (Denne et al., 1990a), county geologic maps (Johnson and Adkison, 1967; Johnson and Wagner, 1967; Ward and O'Connor, 1983), and metric topographic maps (U.S. Geological Survey, 1982). Where bedrock is exposed at the land surface, the bedrock and surface topography are equivalent.

A test hole in SW SE sec. 18, T. 10 S., R. 15 E., confirms the presence of channel deposits more than 66 ft (20 m) deep, with sand and gravel from 8 ft to 36 ft (2-11 m), near Little Soldier Creek. As described earlier, flow may have been southwestward, directly from sec. 18 to sec. 19, T. 10 S., R. 15 E. (between two bedrock "islands"). Alternatively, flow could have been southward in a valley now buried by glacial deposits between Little Soldier and Messhoss creeks. The latter possibility is supported by a well log in SW NE NE sec. 31, T. 10 S., R. 15 E., that indicates sand and gravel layers from 13 ft to 64 ft (4-20 m), a depth to bedrock of 107 ft (32.6 m), and a reported yield of 70 gpm (0.004 m3/s). Several other small, now-buried valleys that probably flowed southerly toward the Kansas River are indicated by drill logs in NW SW NW and SW NW SW sec. 32, T. 10 S., R. 14 E.; SE SE SE sec. 32, T. 10 S., R. 15 E.; NW NE sec. 4, T. 11 S., R. 15 E.; and NE NE NE and NE SE NE sec. 10 and NW SW NW and SE NE SW sec. 11, T. 11 S., R. 15 E., as well as others nearby.

A map view of the glacial-drift deposits that cover the area southeast of the South Branch Shunganunga Creek and the town of Pauline suggests a delta or outwash fan. Logs in this region include SE SE NE sec. 31 and SW SW NE sec. 33, T. 12 S., R. 16 E., and NE NW NW, NW SW NW, and SW SW NW sec. 4, SE SW SE sec. 8, NE NE NW sec. 14, and NE NE sec. 18, T. 13 S., R. 16 E., several of which show a basal sand. One well in particular [SE SE NE sec. 31, T. 12 S., R. 16 E., with a 72-ft (22-m) depth to bedrock and a thick sand] indicates a now-buried valley that may have been connected with Lynn Creek. Additional research should be done in this area to evaluate the character of the deposits, define the extent of the channel (whether it is narrow or part of a broader outwash system), and determine whether the glacial ice extended to the Wakarusa River west of Lynn Creek (either by overriding or being funneled around the bedrock high that begins to the west in central Shawnee County).

The valley of the Shunganunga Creek widens from 0.25 mi to 0.5 mi (0.4-0.8 km) across secs. 10 and 11, T. 12 S., R. 15 E. Whether this is due to the underlying Severy Shale bedrock and/or to the earlier drainage history is unclear.

The depth to bedrock in Shawnee County is shown in fig. 66. The largest known values occur in buried valleys north of the Kansas River and east of Soldier Creek. An oil borehole log in NW NE sec. 4, T. 11 S., R. 15 E., suggests that bedrock is at 120 ft (37 m) with gravel at 24-26 ft (7.3-7.9 m) and sand at 67-75 ft (20-23 m) and 82-120 ft (25-37 m) deep. A water-well record in SW NE NE sec. 31, T. 10 S., R. 15 E., indicates sand and gravel layers between 13 ft (4.0 m) and 64 ft (20 m) and bedrock at 107 ft (32.6 m). The next largest depth to bedrock [93 ft (28 m)] occurs below the Newman terrace in the Kansas River valley.

Figure 66--Depth to bedrock, Shawnee County.

Depth to bedrock, Shawnee County.

Of 117 borehole logs in alluvial deposits [as mapped by Johnson and Adkison (1967) and by Johnson and Wagner (1967)] in the Kansas River valley, 60 do not report reaching bedrock. Of the 57 remaining, 25% (14) identify bedrock between 40 ft (12 m) and 50 ft (15 m) and another 25% (14) indicate bedrock between 70 ft (21 m) and 80 ft (24 m). The largest value is 86 ft (26 m), and all but two sites (near the southern valley wall) have more than 30 ft (9 m) of unconsolidated deposits. In the Newman terrace deposits of the Kansas River valley, logs for 52 wells (out of 126) report bedrock depths. Seventeen (33%) of these depths are between 50 ft (15 m) and 60 ft (18 m). All but three sites (two of which are near the southern valley wall) have more than 40 ft (12 m) of unconsolidated deposits, and the deposit thicknesses range up to 92 ft (28 m). In the Kansas River valley, the depth to bedrock below the alluvial and terrace deposits tends to be greatest [>65 ft (>20 m)] in northeastern Shawnee County near the Muddy Creek junction in adjacent Jefferson County; locally, near the mouth of Shunganunga Creek, especially where the Kansas River shifts from the southern to the northern side of its valley; between the junctions of the Soldier and Halfday Creek valleys with the Kansas River; and near the Cross Creek valley entrance downstream to the Mission Creek junction. The greatest depths correspond to the deepest part of the channel underlying the recent Kansas River valley, as shown on the bedrock topographic map.

The depth to bedrock below alluvial surfaces in other stream valleys in Shawnee County is not well known because of limited data. In the Wakarusa River valley, eight borehole logs indicate that the depths range at least from 18 ft to 36 ft (5.5-11 m). Along Soldier Creek, stream deposits at four sites are 19-54 ft (5.8-16 m) thick. The Shunganunga Creek valley has 18 ft (5.5 m) of alluvial deposits at two sites, while one depth to bedrock value along the South Shunganunga Creek is 27 ft (8.2 m). Mission Creek has 41 ft and 42 ft (13 m) of valley fill at.two sites. Deposits along Halfday Creek and its tributaries range from 26 ft to 44 ft (7.9-13 m) in thickness. Two depth to bedrock values in the Big Muddy Creek valley are 22 ft (6.7 m) and 23 ft (7.0 m). Elsewhere in the county, most stream deposits are between 10 ft (3 m) and 35 ft (11 m) thick.

The depth to bedrock below Buck Creek terrace deposits in Shawnee County is known for only two sites. The values are 31 ft (9.4 m) and 49 ft (15 m) for deposits along Cross Creek and the Kansas River, respectively.

Of 90 drill holes in glacial till and outwash deposits, 83 reportedly reached bedrock. Thirty-three (40%) of the depths to bedrock are in the range 20-40 ft (6-12 m), with a fairly even distribution of most of the other 50 in the remainder of the 10-ft (3-m) increments between 10 ft (3 m) and 80 ft (24 m). The thickness of the glacial deposits tends to be greater north of the Kansas River than south of it. The largest values [120 ft (37 m) and 107 ft (32.6 m), as previously described, and many others from 65 ft to 85 ft (20-26 m)] are associated with small buried valleys that drained southward to the river (e.g., sec. 32, T. 10 S., R. 14 E.; sec. 18, T. 10 S., R. 15 E.; and secs. 10 and 11, T. 11 S., R. 15 E.). Elsewhere in the deposits mapped as Menoken terrace by Davis and Carlson (1952) and Beck (1959), the depth to bedrock commonly ranges from 30 ft to 60 ft (9-18 m). The glacial-drift deposits become thinner farther to the north of the river, with values commonly between 15 ft (4.6 m) and 45 ft (14 m). To the south of the river the glacial drift is generally less than 25 ft (7.6 m) thick, although a thickness of 55 ft (17 m) was reported just south of Shunganunga Creek in SW SW SW sec. 16, T. 12 S., R. 15 E., and values up to 72 ft (22 m) occur in the fan-shaped area of deposits southeast of Pauline.

In areas mapped as bedrock [by Johnson and Adkison (1967) and by Johnson and Wagner (1967)] and those areas that do not have an obviously unmapped cover of glacial deposits, 65 logs indicate that the depth to bedrock is less than 25 ft (7.6 m), and more than half of the values are less than 10 ft (3 m). The unconsolidated material may include loess, colluvium, or residuum. Only one site showed any sand or gravel [sand from 6 ft to 9 ft (2-3 m) in NW NW NE sec. 12, T. 12 S., R. 16 E.], and this may actually be a thin glacial-drift deposit.

Total thicknesses of sand and gravel layers in Shawnee County are shown in fig. 67. The largest values [>82 ft (>25 m) in the Newman terrace in SE NW NW sec. 12, T. 11 S., R. 13 E., and 74-79 ft (23-24 m) in alluvial deposits in SW sec. 18, T. 11 S., R. 14 E., SE SW NE sec. 30, T. 11 S., R. 16 E., NW NW SW sec. 27, T. 11 S., R. 17 E., and NE SE SW sec. 27, T. 11 S., R. 17 E.] occur in the Kansas River valley. Of the remaining 32 logs (out of 65) that reached bedrock below the alluvial deposits of the Kansas River valley, the sand and gravel thickness ranges from 8 ft to 68 ft (2-21 m), with half of the values between 30 ft (9 m) and 50 ft (15 m). In 77 of the 91 logs (85%) of alluvial deposits, sand or gravel begins within 20 ft (6 m) of the land surface. The material generally becomes coarser with depth and includes a basal sand and gravel or gravel layer, which may be 60 ft (18 m) or more thick (e.g., NW SE NW sec. 25, T. 10 S., R. 12 E., and SW sec. 18, T. 11 S., R. 14 E.). Below the Newman terrace of the Kansas River valley, 33 logs for wells that reached bedrock include sand and gravel deposits from 0 to 67 ft (20 m) thick, with 13 (40%) logs each in the ranges 22-40 ft (6.7-12 m) and 50-67 ft (15-20 m). In 85 of 100 logs for Newman terrace deposits, sand or gravel begins 10-40 ft (3-12 m) below the land surface. As in other alluvium, the material generally becomes coarser with depth, although the sequence is sometimes reversed. As might be expected, most of the thickest sand and gravel deposits in the Kansas River valley occur in the same areas as previously described, where the depth to bedrock is greatest. Much of the deeper and coarser material probably is glacial outwash deposited directly into the Kansas River or indirectly through the major tributaries.

Figure 67--Total Pleistocene sand and gravel thickness, Shawnee County.

Total Pleistocene sand and gravel thickness, Shawnee County.

The total thickness of sand and gravel that presently remains in the smaller stream valleys is known only from a limited number of data points. Almost all values are less than 15 ft (4.6 m), if there is any thickness at all. Where there is sand and/or gravel, it is almost always just above bedrock. At eight sites along the Wakarusa River, the Newman terrace has up to 4 ft (1 m) of sand or gravel, whereas along Soldier Creek there is 0-17 ft (0-5.2 m) at four sites. Based on three sites each, Mission Creek stream deposits have 3-8 ft (0.9-2 m) of coarse material; alluvial deposits of the Shunganunga and South Shunganunga creeks have 1-5 ft (0.3-2 m) of basal sand and/or gravel; and Halfday Creek and a tributary have 0-22 ft (0-6.7 m). Two logs in the Big Muddy Creek valley show no sand or gravel.

Two logs in Buck Creek terrace deposits show 5 ft (2 m) of sand and gravel in the Cross Creek valley and 14 ft (4.3 m) in the middle of the unconsolidated deposits in the Kansas River valley.

Of 81 logs for test holes that reached bedrock through glacial deposits, 30% (24) had no sand or gravel and another 55% (45) had values between 1 ft (0.3 m) and 20 ft (6 m). In the other wells the thickness of coarse-grained sediments ranged up to 57 ft (17 m) (NW NW NW sec. 11, T. 11 S., R. 15 E.). The larger values tend to be associated with the small buried valleys north of the Kansas River (e.g., sec. 32, T. 10 S., R. 14 E.; secs. 18 and 31, T. 10 S., R. 15 E.; and sec. 4, T. 11 S., R. 15 E.), and they include alternating layers of sand and gravel that do not necessarily extend to the bedrock surface. Elsewhere in deposits mapped as Menoken terrace, sand and gravel thicknesses range up to 43 ft (13 m), but they are commonly less than 15 ft (4.6 m).

In the fan-shaped area of glacial drift extending southeast from Pauline, the one obvious channel deposit (SE SE NE sec. 31, T. 12 S., R. 16 E.) contains 28 ft (8.5 m) of sand just above bedrock, but only three of six other sites in this area have any [1-10 ft (0.3-3 m)] basal sand or sand and gravel.

Ground water

The greatest quantities of ground water available in Shawnee County are from Newman terrace deposits and other alluvium in the Kansas River valley. Well yields range up to 2,500 gpm (0.16 m3/s), with values of at least 2,000 gpm (0.13 m3/s) reported in SW NW NW sec. 24 and NW SE NW and NE SW SW sec. 25, T. 10 S., R. 12 E.; SE NW NW sec. 12, T. 11 S., R. 13 E.; NW SW NE sec. 15, NW sec. 16, NE SW SE sec. 17, and SW sec. 18, T. 11 S., R. 14 E.; NE SE NE sec. 14, T. 11 S., R. 15 E.; and NE SE SW sec. 27, T. 11 S., R. 17 E. Reported well yields (uncorrected for such factors as well diameter and length of aquifer screened) are shown in fig. 68.

Figure 68--Estimated well yields, Shawnee County.

Estimated well yields, Shawnee County.

In the Kansas River valley alluvial deposits, yields were reported for 80 wells. Seventy percent (56) of the wells produce at least 100 gpm (0.006 m3/s), and 40% (32) yield at least 1,000 gpm (0.06 m3/s). Most of the remaining yields are between 20 gpm (0.001 m3/s) and 50 gpm (0.003 m3/s). In the Newman terrace deposits of the Kansas River valley, 47 (50%) of95 wells reportedly produce at least 100 gpm (0.006 m3/s), and 23 (25%) have yields of 1000 gpm (0.06 m3/s) or more. Most of the other wells have values between 10 gpm (0.0006 m3/s) and 60 gpm (0.004 m3/s).

In the smaller stream valleys of Shawnee County well yields are generally 20 gpm (0.001 m3/s) or less. In the Newman terrace deposits of the Wakarusa River valley, seven values range from 0.5 gpm to 10 gpm (0.00003-0.0006 m3/s). Along Soldier Creek stream deposits yield 4-20 gpm (0.0003-0.001 m3/s) to three wells. Alluvial deposits of the Shunganunga and South Shunganunga creeks produce 7-10 gpm (0.0004-0.0006 m3/s) to another three wells. One well in the Buck Creek terrace deposits of Cross Creek produces 10 gpm (0.0006 m3/s).

Sixty-seven wells in the glacial-drift deposits reportedly yield up to 100 gpm (0.006 m3/s). Forty-five percent (30) produce 1-5 gpm (0.00006-0.0003 m3/s), and 30% (20) yield 10-20 gpm (0.0006-0.001 m3/s). The largest value [100 gpm (0.006 m3/s) in NE SW SE sec. 10, T. 11 S., R. 16 E.] apparently comes from 8 ft (2 m) of basal sand and gravel below a small modern tributary valley to the Kansas River. Several other values of 25 gpm to 70 gpm (0.0016-0.0044 m3/s) (SW NE NE sec. 31, T. 10 S., R. 15 E.; SE SW SW sec. 6, SE NW NE sec. 10, and NW NW NW sec. 11, T. 11 S., R. 15 E.) also are connected with buried valleys and/or the Menoken terrace on the northern side of the Kansas River and in glacial or high-terrace deposits north of the Wakarusa River (NE NW SE sec. 21, T. 13 S., R. 17 E). Two other wells north of the Wakarusa River (NW NW NE and SW SE NW sec. 24, T. 13 S., R. 14 E., in the Auburn area, as previously described) have relatively high yields [15-20 gpm (0.0009-0.001 m3/s)], which apparently come from clay with sand and gravel and possibly the underlying 3-ft (0.9-m) sandstone layer in the SW SE NW sec. 24 well.

The yields of 43 wells that obtain most of their water from bedrock units in Shawnee County range from 0 to 12 gpm (0.00076 m3/s). Thirty percent (13) produce less than 1 gpm (0.00006 m3/s), and 45% (19) yield 1-5 gpm (0.00006-0.0003 m3/s). The larger values generally seem to be associated with sandstones in the Onaga, Scranton, and Severy Shales and with weathered near-surface rocks, including the Calhoun Shale and the Deer Creek Limestone. All or part of the water from some wells in glacial and tributary stream deposits also comes from underlying bedrock units. Notable examples include a well near a tributary of Halfday Creek (SE SW SW sec. 14, T. 10 S., R. 15 E.), which reportedly produces 40 gpm (0.003 m3/s) from a I-ft (O.3-m) limestone layer (probably the Rulo Limestone Member of the Scranton Shale) that underlies 31 ft (9.4 m) of clay, and wells in SW SW NE sec. 15, T. 10 S., R. 13 E., SW SE NE sec. 3, T. 11 S., R. 14 E., and SE SW SE sec. 20, T. 12 S., R. 17 E., which yield 15-20 gpm (0.00095- 0.0013 m3/s).

The depth to water reported for wells in Shawnee County (fig. 69) must be viewed with the same caution as described previously for other counties. The measurements were not taken at a consistent time and may include wells that were not yet fully developed, penetrate a confined aquifer, and/or obtain water from more than one aquifer and therefore provide only composite water levels. Nevertheless, some generalizations can be made. Where water is encountered in drill holes, the levels are relatively shallow. The largest values [65-80 ft (20-24 m)] are found in wells penetrating bedrock and/or glacial deposits (including the Menoken terrace) in SW NW NE sec. 32 and NE NW NW sec. 33, T. 10 S., R. 15 E., and SE SW SW sec. 6, NW NE SW sec. 9, and NW NW NW sec. 11, T. 11 S., R. 15 E.

Figure 69--Depth to water in wells and test wells, Shawnee County.

Depth to water in wells and test wells, Shawnee County.

Water levels in 35 of 42 bedrock wells were fairly evenly distributed among 10-ft (3-m) incremental values less than 50 ft (15 m). The remainder ranged from 50 ft to 80 ft (15-24 m). In glacial deposits 40% (29) of 73 wells had water levels between 10 ft (3 m) and 19 ft (5.8 m), whereas 10% (7) had depths to water of less than 10 ft (3 m) and seven each had depths in the 10-ft (3-m) intervals between 20 ft (6 m) and 49 ft (15 m). The remaining wells had values between 50 ft (15 m) and 70 ft (21 m). Three test holes that went only to or slightly below the bedrock contact were dry. The depth to water in two Buck Creek terrace deposit wells ranged from 17 ft to 20 ft (5.2-6 m).

Newman terrace water levels ranged from 9 ft to 34 ft (3-10 m) in 112 wells in the Kansas River valley, and 95% (106) of the wells had values greater than 15 ft (4.6 m). Depths to water in seven wells in the Wakarusa River valley Newman terrace deposits were all between 10 ft (3 m) and 20 ft (6 m). Elsewhere in the county, Newman terrace water levels ranged from 4 ft to 30 ft (1-9 m), and some wells in the terrace deposits obtained water from the underlying bedrock units.

The depth to water in alluvium in the Kansas River valley ranged from 6 ft to 37 ft (2-11 m) in 103 wells, with 50% (52) from 9 ft to 19 ft (3-5.8 m) and 41 % (42) from 20 ft to 30 ft (6-9 m). In other valleys water levels in the alluvial deposits ranged from 7 ft to 15 ft (2-4.6 m) in six wells.

The elevations of water in the Kansas River valley range from 915 ft (279 m) near the western border of Shawnee County to 830 ft (250 m) near the eastern border. This indicates an average hydraulic gradient in the valley of 3 ft/mi (0.6 m/km). Elsewhere in the county a gross contour map of the water elevations indicates a reflection of the land-surface topography, with a drainage divide and ground-water flow toward the Wakarusa River in the southern townships and flow toward the Kansas River and its tributaries in the northern part of the county. Heavy pumpage, especially in the Kansas River valley, may cause local depressions in the water level.

The total saturated thickness of Pleistocene unconsolidated deposits in Shawnee County (fig. 70) reflects the same limitations as the depth to water data from which these values were calculated. The largest thicknesses appear to occur in the glacial buried valleys [72 ft (22 m) in SW NW SW sec. 32, T. 10 S., R. 14 E., and SW NE NE sec. 31, T. 10 S., R. 15 E.] and in the Kansas River alluvial and Newman terrace deposits [65-68 ft (20-21 m) in SE NW NW sec. 12, T. 11 S., R. 13 E.; SE NW SW sec. 14 and SW NE NW sec. 23, T. 11 S., R. 14 E.; NE NE SE and SW NW SW sec. 13, T. 11 S., R. 15 E.; and NE SE SW sec. 27, T. 11 S., R. 17 E.].

Figure 70--Saturated thickness of Pleistocene deposits, Shawnee County.

Saturated thickness of Pleistocene deposits, Shawnee County.

Because many wells in Newman terrace deposits and other alluvium do not reach bedrock, the saturated thickness of unconsolidated deposits at these sites can only be stated as greater than the given numerical value. In the Kansas River valley the saturated thickness of alluvial deposits is greater than 65 ft (20 m). Of 44 wells that reach bedrock below the alluvium, 27-30% (12 or 13) have saturated thicknesses in each of the depth ranges 20-29 ft (6.1-8.8 m), 30-39 ft (9-12 m), and 50-59 ft (15-18 m). Six wells in alluvial deposits other than those of the Kansas River valley have saturated thicknesses of 3-25 ft (0.9-7.6 m).

The saturated thickness of Newman terrace deposits in the Kansas River valley ranges from 3 ft to 68 ft (0.9-21 m). Of 43 wells that reach bedrock below the terrace deposits, 50% (22) have saturated thicknesses of 20-40 ft (6-12 m) and 35% (15) have values of 50-68 ft (15- 21 m). In the Wakarusa River valley, Newman terrace deposits have saturated thicknesses of 1-23 ft (0.3-7.0 m) at 7 sites. Three wells in Soldier Creek indicate values of 2-37 ft (0.6-11 m). Along other streams 14 sites indicate 0-17 ft (0-5.2 m) of saturated thickness.

Data are limited for the saturated thickness of Buck Creek terrace deposits. One well indicated 11 ft (3.4 m) along Cross Creek, and another indicated 32 ft (9.8 m) in the Kansas River valley.

The saturated thickness of glacial deposits in Shawnee County ranges from 0 to 72 ft (22 m) at 72 sites. Twelve percent (nine) are dry, and 80% (58) range from 1 ft to 29 ft (0.3-8.8 m). The larger values [>50 ft (>15 m)] are associated with the buried valleys east of Soldier Creek on the western side of T. 10 S., R. 15 E., and in southwestern T. 10 S., R. 14 E. The Menoken terrace deposits have saturated thicknesses ranging from 3 ft to 25 ft (0.9-7.6 m) at 13 sites. Five wells in the fan area near Pauline indicate saturated thicknesses of 0-29 ft (0-8.8 m).

In bedrock areas of Shawnee County the overlying unconsolidated deposits (residual soils or thin glacial deposits or loess) have saturated thicknesses of less than 15 ft (4.6 m). Of 48 sites, 41 (85%) actually have no saturated deposits above the rock.

Aquifer tests for four wells in the Kansas River valley that were pumped at 225-850 gpm (0.0142-0.0536 m3/s) indicate transmissivity values from 14,700 ft2/d to 48,000 ft2/d [110,000-360,000 gpd/ft (1370-4460 m2/d)] and storage coefficients from 0.02 to 0.09 (Fader, 1974). Based on well locations and Fader's geologic maps, the largest transmissivity value appears to be associated with alluvium, whereas the other three wells may be in Newman terrace deposits (two of which are near the border with alluvium).

In Shawnee County the major discharge of ground water is to wells, streams, and evapotranspiration. Ground-water recharge is primarily from precipitation and flooding of rivers. The most important source of ground water in the county is from deposits in the Kansas River valley and some glacial buried channels.

Wabaunsee County

Geology

The geology of Wabaunsee County has been mapped and described by Mudge and Burton (1959). Fader (1974) and Beck (1959) also discussed deposits along the Kansas River in this area. Geologic units exposed in the county include alluvial, terrace, colluvial, loess, and glacial deposits and Upper Pennsylvanian and Lower Permian bedrock (figs. 5 and 9).

As described by Mudge and Burton (1959), the northern part ofWabaunsee County is a till plain with rounded hills; the eastern area is a broad, flat lowland with incised streams formed on easily dissected bedrock; the western and central parts of the county include the Flint Hills upland and escarpment [the bluff of which is 125 ft (38 m) above the lowland]. The drainage pattern is dendritic.

The structure of Wabaunsee County includes the post-Mississippian Forest City basin and the Nemaha and Alma anticlines and the pre-Mississippian North Kansas basin (Mudge and Burton, 1959). Other smaller structures include anticlines west of Alma and northeast of Eskridge, a basin northeast of Alta Vista, and small normal faults in the northwestern part of the county. Exposed rocks have a general dip to the northwest, although they are relatively flat lying. The average thickness of the rocks that are exposed in the county is 575 ft (175 m).

The oldest rocks exposed in Wabaunsee County are Upper Pennsylvanian in age, and outcrops occur mainly in stream banks and road cuts in the northern and eastern parts of the county (Mudge and Burton, 1959). The units include the Auburn Shale, the Emporia Limestone, the Willard Shale, the Zeandale Limestone, the Pillsbury Shale, the Stotler Limestone, the Root Shale, and the Wood Siding Formation of the Wabaunsee Group. These units range from 170-450 ft (52-140 m) in total thickness, with an average of 225 ft (68.6 m). Thin, dark, fossiliferous limestones and relatively thick, gray to olive-drab, nonfossiliferous shales predominate, but sandstone, sandy shale, conglomerate, and coal occur locally. Channel sandstones occur in and below the Pony Creek and Plumb Shale Members of the Wood Siding Formation, and sandstone lenses can be found in the Dry Shale Member of the Stotler Limestone, in the Wamego Shale Member of the Zeandale Limestone, and in the Pillsbury and Willard Shales. Iron stains are common on exposures of the Wabaunsee Group. Celestite occurs in some of the pores of the Tarkio Limestone Member of the Zeandale Limestone, and barite and gypsum occur locally in the Wood Siding Formation.

According to Mudge and Burton (1959), the lowermost 100 ft (30 m) of Permian (Admire Group) rocks in Wabaunsee County are similar in lithology to the Pennsylvanian units. They include thick, nonfossiliferous shales and thin limestones with some sandy shale, sandstone, coal, and conglomerate. The Admire Group is 100-220 ft (30-67 m) thick and is exposed primarily in northern and eastern Wabaunsee County. Channel deposits on the Towle Shale Member of the Onaga Shale are exposed from 4 mi (6 km) east of Keene to the Shawnee County border (which would be in or near sec. 3, T. 13 S., R. 13 E.). Local channel sandstones and lenses of sandstone also occur in the West Branch and Hamlin Shale Members of the Janesville Shale. Some seeps occur at the base of the Hamlin sandstones. One limestone unit in the West Branch Shale Member is porous to cavernous and has many small calcite-filled fractures, and a coquina limestone facies in the overlying Five Point Limestone Member is exposed in the northern to central part of the county. The Falls City Limestone lies between the Onaga and Janesville Shales. In the Admire Group the shales are gray; bluish, tan or brownish gray; grayish green; green; or maroon. The limestones are typically gray to tan or brownish gray. Charcoal or carbonized plant fragments and iron stains occur locally.

Younger Permian rocks exposed in Wabaunsee County are generally thicker light (white to gray to tan) limestones and thick, brightly variegated gray, olive, tan, green, maroon, and purple fossiliferous shales (Mudge and Burton, 1959). The limestone to shale ratio of these units is larger than in the Lower Permian and Upper Pennsylvanian rocks.

The Council Grove Group includes, in ascending order, the Foraker Limestone, the Johnson Shale, the Red Eagle Limestone, the Roca Shale, the Grenola Limestone, the Eskridge Shale, the Beattie Limestone, the Stearns Shale, the Bader Limestone, the Easly Creek Shale, the Crouse Limestone, the Blue Rapids Shale, the Funston Limestone, and the Speiser Shale. As described by Mudge and Burton (1959), the total thickness of the group is 250-425 ft (76-130 m), and it is dominated by limestones and shales with some local coal, sandstone (especially in the Easly Creek Shale), and conglomerate. The limestones are typically gray to brown, tan, blue or orange-gray. The shales are gray, grayish green, tan, olive, green, purple, maroon, or black. Exposures are most extensive in central Wabaunsee County, but they occur in approximately three-quarters of the county. Limestones that are or weather to porous to cavernous occur in the Foraker, Red Eagle, Grenola, Beattie, Bader, Crouse, and Funston Limestones and the Roca and Stearns Shales (including especially the Long Creek, Howe, Neva, Morrill, Cottonwood, Eiss, and Middleburg Limestone Members and the Bennett Shale Member). Seeps or springs are present in many of the same formations. Celestite occurs locally in the Foraker and Red Eagle Limestones, and the Red Eagle and Beattie Limestones contain some chert. Iron stains and carbonized plant fragments occur locally.

In Wabaunsee County the Chase Group (Permian) includes the Wreford Limestone, Matfield Shale, Barneston Limestone, and that part of the Doyle Shale below the Holmesville Shale Member (Mudge and Burton, 1959). These units are 130-225 ft (40-68.6 m) thick and are exposed in the western, central, and southcentral parts of the county. The limestones are white, gray, or tannish brown to tannish gray. The shales are gray, grayish green, tannish gray, bluish gray, green, olive, maroon, and purple. Iron stains are common locally. Limestones that are or weather to porous to cavernous occur in the Wreford and Barneston Limestones, and many seeps and springs are associated with the Chase Group. The Threemile, Schroyer, and Florence Limestone Members of the Wreford and Barneston Limestones contain chert, and the Wreford is the oldest Permian formation of the Flint Hills escarpment.

The oldest unconsolidated deposits in Wabaunsee County are Tertiary or early Quaternary chert gravels. The chert was derived primarily from the Wreford and Barneston Limestones of the Chase Group, with some also from the Cottonwood Limestone Member of the Beattie Limestone (Council Grove Group) (Mudge and Burton, 1959). The chert is angular to subrounded in sand- to cobble-size fragments, but it is dominated by pebbles and granules. The chert generally has a reddish-brown clay (with some silt and very fine grained sand) matrix. The deposits are 0-15 ft (0-4.6 m) thick but average 8 ft (2 m). Locally, the lower foot is a well-cemented conglomerate. The deposits may indicate ancestral drainageways. Todd (1918b) described chert gravel deposits underlying red quartzite boulders at Alma and Paxico in the Mill Creek valley. Other thick chert gravel beds occur on strath (remnant) terraces along and 60-120 ft (18-37 m) above the modern streambeds of the Marais des Cygnes River, Rock Creek, and Mill Creek and its tributaries and in SENE sec. 5, T. 14 S., R. 9 E., and NE sec. 5, T. 14 S., R. 13 E. (Mudge and Burton, 1959). Johnson and Wagner (1967) also described deposits in SE sec. 32 and in eastern sec. 34, T. 13 S., R. 13 E. Other thick chert gravels extend from southwest of Alma to the Kansas River terrace in the southwestern part of T. 10 S., R. 12 E., and Mudge (1955) suggested that these gravels were deposited by a more direct-flowing preglacial Mill Creek. Those deposits that are north-northeast of Paxico are overlain by glacial till, and the two altitudes of chert gravels in sec. 6, T. 11 S., R. 12 E., may indicate episodes of aggradation and intermediate degradation (Mudge and Burton, 1959). Many seeps occur at the base of the chert gravels.

Glacial-till deposits in Wabaunsee County generally consist of 0-50 ft (0-15 m) of light-gray to gray-brown (locally tan to bluish) unstratified clay with some silt, sand, and gravel to boulders that range in size up to 18 x 17 x 6 ft (5.5 x 5.2 x 2 m) (Mudge and Burton, 1959). The coarse material includes local limestone, chert, shale, and sandstone and igneous and metamorphic erratics (granite, quartzite, greenstone, and gneiss). A concentration of boulders in northern and northeastern Wabaunsee County may indicate remnants of a terminal moraine and corresponds with Aber's (l988a, 1991) late Independence glacial limit (see fig. 7). Till deposits are north of the glacial limit, which, as interpreted by Mudge and Burton (1959), Smyth (1898), Schoewe (1930b, 1939), and Mudge (1955), extends from the northwestern comer of the county, eastward along Mill Creek from east of McFarland to Maple Hill, and then southeastward to sec. 27 or 34, T. 12 S., R. 13 E. Some banded or varved sediments in SESE sec. 28 and SE sec. 29, T. 11 S., R. 13 E., and SW SW sec. 7, T. 11 S., R. 12 E., include light and dark gray-brown very fine grained sand, silt, and clay with some erratic gravel (Mudge and Burton, 1959) and may represent the Atchison Formation of Johnson and Wagner (1967). Small, elongated northeast-trending ridges composed predominantly of erratic boulders and cobbles in NW sec. 25, T. 10 S., R. 10 E., may be drumlin remnants (Mudge and Burton, 1959). Exposures of till are commonly iron stained, contain some carbon, and have carbonate nodules in the upper parts. Seeps and springs occur locally above, within, or below the till deposits.

Glacial ice-contact deposits in secs. 9 and 10, T. 12 S., R. 13 E., have been described by Mudge and Burton (1959). The deposits average 30 ft (9 m) in thickness, where present, and include fine-grained sand to boulders (with cobbles common but smaller grains most abundant). The erratics are generally well rounded, and, as in the till, the larger pieces of granite are often decomposed. In addition to igneous and metamorphic erratics, some limestone, chert, shale, and blocks of till ranging up to 6 ft (2 m) in diameter are included. The deposits are locally cemented by calcium carbonate. Size sorting and crossbedding are not obvious. These ice-contact deposits overlie Pennsylvanian bedrock, and in sec. 10, T. 12 S., R. 13 E., they fill a small preglacial Valley. Small springs occur below many of the gravel deposits.

Mudge and Burton (1959) also described deposits of what they termed the Grand Island, Sappa, and Sanborn formations in Wabaunsee County. These formation names are no longer used for this area. The first two are part of the classical Kansan Stage, and the third includes Illinoian and younger sediments.

The Grand Island Formation of Mudge and Burton (1959) includes an average of 3 ft (0.9) of limestone and chert gravels in the southeastern, unglaciated part of Wabaunsee County and 6 ft (2 m) of glacial outwash sands and gravels in the northern areas. In the north, deposits are exposed in secs. 7 and 16, T. 11 S., R. 12 E., secs. 14, 15, and 22, T. 11 S., R. 10 E., and the Paw Paw Creek valley. Some of these probably indicate drainageways of small outwash streams that flowed southward to Mill Creek. In addition to limestone and chert the outwash sands and gravels also include rounded erratics, red-brown silt, and clay balls. The northern outwash deposits commonly overlie glacial till, but sometimes they are intermixed. Other deposits are exposed southeast of Eskridge (secs. 9,16, and 22, T. 14 S., R. 12 E., where the subrounded limestone, chert, and shale gravel is mixed with light-gray clay), north of Mission Creek [sec. 33, T. 12 S., R. 13 E., and secs. 5 and 6, T. 13 S., R. 13 E., where limestone gravel rests 50 ft (15 m) above the modern streambed], on opposite sides of Snokomo Creek south of Mill Creek (secs. 35 and 36, T. 11 S., R. 11 E.), and near the Marais des Cygnes River (sec. 7, T. 15 S., R. 12 E.). Johnson and Wagner (1967) described another deposit north of Mission Creek [9 ft (3 m) exposed in NW NW sec. 3, T. 13 S., R. 13 E.] that has sub angular to subrounded gravel dominated by limestone but including chert, quartz, and ironstone and overlain by sand composed of limestone, sandstone, chert, quartz, ironstone, and fossil fragments and some well-cemented lenses of sand and gravel. The sand layers dip east-southeast. These Kansan terrace deposits, as classified by Johnson and Wagner (1967), make the Mission Creek valley wider in Wabaunsee County than it is downstream in Shawnee County. Seeps are common below the Grand Island gravels. The Sappa and Sanborn formations may overlie the Grand Island Formation of Mudge and Burton (1959).

Where present (e.g., in exposures southeast of Eskridge in secs. 9, 10, 16, and 22, T. 14 S., R. 12 E.), the Sappa Formation includes 3 ft (0.9 m) of dark-gray to gray-brown alluvial or colluvial clayey gravel and clay, locally with a buried soil at the top (Mudge and Burton, 1959). Calcium carbonate is abundant in the upper zones and in fracture and root (?) fillings. Kansanage mollusks and ostracodes are common in the deposits (Frye and Leonard, 1952). Seeps occur locally at the top of the relatively impermeable buried soil.

As mapped and described by Mudge and Burton (1959), the Sanborn formation may include alluvial deposits of and younger than the Crete Formation, loess of the Loveland and Peoria formations, the Sangamon Soil, and colluvial and slope wash deposits and small amounts of the pre-Illinoian materials previously described. Typically, the deposits are 0-15 ft (0-4.6 m) thick. Gravels assigned to the Crete Formation occur 30-40 ft (9-12 m) above Mill Creek (e.g., NE NW sec. 22 and NE SE sec. 26, T. 11 S., R. 12 E.), near the upper reaches of Dragoon Creek (SE sec. 16, T. 14 S., R. 12 E.), and along Illinois, Middle Branch, Spring, Horse, and Rock creeks and the Marais des Cygnes River. The deposits, which generally range from 3 ft to 12 ft (0.9-3.7 m) in thickness, include chert, limestone, and/or shale gravel mixed with erratics in the northern areas. The gravels commonly have a grayish- to reddish-brown clay, silt, and/or fine-grained sand matrix. The basal portion of the Crete Formation may include a cemented conglomerate.

Loess deposits range from grayish- to tannish- to reddish-brown silt and clay. Deposits are locally iron stained. The Loveland loess (Illinoian) averages 4 ft (1 m) in thickness, whereas the Peoria loess (Wisconsin) is thicker [10 ft (3 m) on average] and more widespread. The reddish-brown Sangamon Soil and modern soils are locally developed in the upper Loveland loess and Peoria loess, respectively, and both are commonly leached of carbonates. Colluvial, slope wash, and some small tributary stream deposits range up to 15 ft (4.6 m) in thickness, include gravel (typically limestone and chert with some shale) in a gray to grayish-brown to reddish-brown clay to silty clay matrix and may be intermixed with loess and terrace deposits. Seeps occur commonly below gravel deposits, above the Sangamon Soil, and at bedrock contacts.

Alluvial deposits in Wabaunsee County include the Illinoian Buck Creek terrace and the Wisconsin to Holocene Newman terrace and modern alluvium (Mudge and Burton, 1959). Terraces occur along most streams, with widths up to 4 mi (6 km) in the Kansas River valley, 1.5 mi (2.4 km) along Mill Creek, and 0.5 mi (0.8 km) near other streams. The alluvial deposits range up to 60 ft (18 m) in thickness, and they typically include grayish-brown to reddish-brown silt and clay with basal limestone and chert gravel. Along the Kansas River, the Buck Creek and Newman terraces lie 50-60 ft (15-18 m) and 10-15 ft (3-5 m), respectively, above the modern streambed. Recent alluvium ranges up to 1.5 mi (2.4 km) wide along the Kansas River, but it is more commonly 0.5 mi (0.8 km) or less. Along other drainageways the alluvium ranges from approximately the stream width to 0.5 mi (0.8 km) wide. The deposits are generally tannish- to grayish-brown silt and clay overlying sand and gravel. In the Kansas River valley, the surficial deposits are coarser and consist of fine-grained sand, clayey silt, and some gravel lenses. The sand includes quartz, feldspar, and dark basic (mafic) minerals, but the gravel is dominated by limestone and chert. Alluvial deposits are less than 100 ft (30 m) thick.

Gray to light-gray porous calcium carbonate travertine deposits occur near three springs (SW sec. 12 and NE sec. 21, T. 12 S., R. 10 E., and SE sec. 4, T. 14 S., R. 11 E.) in Wabaunsee County (Mudge and Burton, 1959). The deposits are 3-12 ft (0.9-3.7 m) thick, contain leaf and wood fragments, and have steeply inclined beds.

The drainage history of Wabaunsee County has been described by Smyth (1898), Mudge (1955), Mudge and Burton (1959), and Johnson and Wagner (1967). Ice dammed the Kansas River at St. George in Pottawatomie County (just northwest of Wabaunsee County), and water flowed southeastward through diversion channels in northern Wabaunsee County to the modern junction of Mill and Dry creeks near Maple Hill, where water ponded and then spilled over the divide and drained toward the part of Mission Creek north of Dover in Shawnee County.

The bedrock topography of Wabaunsee County is shown in plate 1. This map was constructed using 328 bedrock-elevation data points [see Denne et al. (1990a)], the county geologic map (Mudge and Burton, 1959), and generalized surface topographic maps (U.S. Geological Survey, 1969a, b, 1974a,b) with modifications from some of the corresponding topographic quadrangle maps (1 :62,500 scale). The valleys of the Kansas River and Mill Creek are the most prominent bedrock lows in the area.

A few buried valleys occur in Wabaunsee County. As previously described, the chert gravels from southwest of Alma to the Kansas River terrace in southwestern T. 10 S., R. 12 E., indicated the ancestral drainageway of Mill Creek to Mudge (1955). Additional bedrock elevation data are needed to define any now-buried parts of this channel, especially between Paxico and Turkey Creek in northeastern T. 11 S., R. 11 E., and northwestern T. 11 S., R. 12 E. For a start, a water well in SW SW NW sec. 12, T. 11 S., R. 11 E., indicates 30 ft (9 m) of sand and gravel. Mudge and Burton (1959) also suggested that some of the deposits they classified as Grand Island Formation may represent former outwash streams that flowed southward to Mill Creek (e.g., secs. 7 and 16, T. 11 S., R. 12 E.; secs. 14, 15, and 22, T. 11 S., R. 10 E.; and the Paw Paw Creek valley). The modern Antelope, Wells, and Roberts Creek valleys are relatively wide and may indicate some relationship to former drainageways. The oil-borehole log for SW SW NE sec. 6, T. 11 S., R. 10 E., may help to define a buried valley west of the modern Antelope Creek. If correct, the oil logs for NE NE NE sec. 21, T. 12 S., R. 9 E., and NE NW NE sec. 22, T. 13 S., R. 10 E., which report sand and gravel in the intervals 5-100 ft (2-30 m) and 30-80 ft (9-24 m), respectively, may indicate buried tributaries to the modern Spring and Middle Branch Mill creeks. On a small scale the glacial ice-contact deposits exposed in sec. 10, T. 12 S., R. 13 E., fill a small preglacial valley cut in Pennsylvanian bedrock (Mudge and Burton, 1959).

The depth to bedrock in Wabaunsee County is shown in fig. 71. The largest depth values are questionable; oil records for boreholes in SW NE sec. 6, T. 11 S., R. 10 E., SW NE sec. 26, T. 11 S., R. 11 E., NE NE NE sec. 21, T. 12 S., R. 9 E., SW SE SE sec. 33, T. 13 S., R. 10 E., SE SW NW sec. 3, T. 14 S., R. 10 E., and NW NW NW sec. 35, T. 14 S., R. 10 E., indicate bedrock depths between 90 ft (27 m) and 217 ft (66.1 m). Some of these depths may indicate buried valleys, whereas others (mostly in areas with rocks of the lower Chase, upper Council Grove, and upper Wabaunsee groups) may simply not provide enough information to differentiate unconsolidated sediments from bedrock.

Figure 71--Depth to bedrock, Wabaunsee County.

Depth to bedrock, Wabaunsee County.

Of well logs that indicate depth to bedrock (Denne et al., 1990a) in alluvial deposits, as mapped by Mudge and Burton (1959), five show depths from 36 ft to 70 ft (11-21 m) in the Kansas River valley and seven indicate depths between 33 ft (10 m) and 50 ft (15 m) along Mill Creek. Below Newman terrace deposits [again as mapped by Mudge and Burton (1959)], bedrock depths range from 29 ft to 85 ft (8.8-26 m) [with 24 of 27 values greater than 40 ft (12 m)] along the Kansas River, from 44 ft to 49 ft (13-15 m) for three sites in the Mill Creek valley, and from 30 ft to 35 ft (9-11 m) at three points along Wells and Hendricks creeks. Undifferentiated terrace deposits range from 24 ft to 60 ft (7.3-18 m) in thickness [with most of 13 values between 43 ft (13 m) and 49 ft (15 m)] along Mill Creek. One to three sites each indicate that the depth to bedrock below undifferentiated terrace deposits in the South Branch Mission, East Branch Mill, Snokomo, Paw Paw, and Mulberry Creek valleys ranges from 19 ft to 29 ft (5.8-8.8 m). The Buck Creek terrace deposits are 39-53 ft (12-16 m) thick at four sites along Mill Creek and 25- 85 ft (7.6-26 m) thick [with most between 48 ft (15 m) and 69 ft (21 m)] along the Kansas River valley and its junctions with other drainages.

The depth to bedrock below deposits mapped by Mudge and Burton (1959) as the Sanborn Formation (which probably overlies glacial till in many cases) ranges up to 100 ft (30 m) (with several questionable values, as previously discussed). Nearly half of the 90 sites indicate depths between 10 ft (3 m) and 19 ft (5.8 m), with another 20% (18) between 20 ft (6 m) and 29 ft (8.8 m) and 10% (9) between 30 ft (9 m) and 39 ft (12 m). The larger depths occur in the northern, glaciated area of the county and parts of the southern townships. The thickness of glacial drift at four sites is 10 ft (3.0 m), 15 ft (4.6 m), 45 ft (14 m), and 52 ft (16 m). The Sappa and Grand Island Formations of Mudge and Burton (1959) are at least 14-16 ft (4.3-4.9 m) thick at two locations. Residual, colluvial, or other Quaternary deposits are typically less than 10 ft (3 m) thick over bedrock.

Total Pleistocene sand and gravel thicknesses in Wabaunsee County are shown in fig. 72. The oil-borehole record for NENENE sec. 21, T. 12 S., R. 9 E., as previously described, indicates 95 ft (29 m) of sand and gravel (which would be the maximum value for the county) in an area mapped by Mudge and Burton (1959) as marginal between the Sanborn Formation and bedrock, but the deposits may indicate a buried channel. Other large sand and gravel values [between 58 ft (18 m) and 74 ft (23 m)] occur in the Kansas River alluvium and Newman terrace deposits in NW NW sec. 22, T. 10 S., R. 12 E., SE SE SE sec. 16, T. 10 S., R. 12 E., and SE SW NW sec. 10, T. 10 S., R. 11 E. Elsewhere along the Kansas River, the sand and gravel thickness ranges are 0-28 ft (0-8.5 m) in the alluvium, 12-64 ft (3.7-20 m) in the Newman terrace deposits, and 9-41 ft (3-12 m) in the Buck Creek terrace. The largest thicknesses tend to be near the junctions with Antelope, Wells, and Mill creeks and near St. Mary's (ancestral Mill Creek connection). The coarse-grained material in the Kansas River valley commonly is finer near the land surface [beginning at depths of less than 20 ft (6 m) in the alluvium and Newman terrace and between 25 ft (7.6 m) and 40 ft (12 m) in the Buck Creek terrace] and becomes coarser with depth. A basal gravel [up to 54 ft (16 m) thick in SE SW NW sec. 10, T. 10 S., R. 11 E.] typically overlies bedrock.

Figure 72--Total Pleistocene sand and gravel thickness, Wabaunsee County.

Total Pleistocene sand and gravel thickness, Wabaunsee County.

Basal gravel or sand and gravel also overlie bedrock below most of the other stream deposits in Wabaunsee County. Sand occurs locally above some of the basal gravels. The total sand and gravel thickness ranges up to 30 ft (9 m) along Mill Creek, 14 ft (4.3 m) in the Mulberry Creek valley, 7 ft (2 m) near Hendricks, Snokomo, and South Branch Mission creeks, and 5 ft (2 m) along other streams.

In deposits mapped as the Sanborn Formation and/or glacial till by Mudge and Burton (1959), 64 (75%) of 85 logs (Denne et al., 1990a) show no sand and gravel. Sixteen sites (19%) have 2-11 ft (0.6-3.4 m) of basal gravel or sand or both. Three other sites (4%) (NW NE NE sec. 20, T. 12 S., R. 13 E., SW SW NW sec. 25, T. 10 S., R. 10 E., and SW SW NW sec. 12, T. 11 S., R. 11 E.) have 19-25 ft (5.8-7.6 m) of fine-grained sand, and the well in T. 11 S. has 10 ft (3 m) of basal gravel. One measured section in SE SE sec. 16, T. 14 S., R. 12 E., shows 3 ft (0.9 m) of Grand Island Formation gravel overlying bedrock.

Sand and gravel in the alluvial and terrace deposits along the major drainageways and locally in the glacial deposits and some bedrock units are the major sources of ground water in Wabaunsee County.

Ground Water

Alluvial and Newman terrace deposits along the Kansas River produce the largest quantities of water to wells in Wabaunsee County. Figure 73 shows reported yields (uncorrected for well diameter, screen length, pump capacity, and other variables). Yields between 1,000 gpm (0.06 m3/s) and 2,500 gpm (0.16 m3/s) have been reported in sec. 17, T. 10 S., R. 10 E.; sec. 10, T. 10 S., R. 11 E.; secs. 8, 16, 17, and 22, T. 10 S., R. 12 E.; and sec. 9, T. 11 S., R. 13 E. These large yields correspond to the areas with the greatest sand and gravel thicknesses. Other wells in the Newman terrace deposits along the Kansas River produce 25-450 gpm (0.0016-0.028 m3/s), whereas wells in the Buck Creek terrace report yields of 20-50 gpm (0.001-0.003 m3/s).

Figure 73--Estimated well yields, Wabaunsee County.

Estimated well yields, Wabaunsee County.

Wells in the Mill Creek alluvium and terrace deposits produce 6-125 gpm (0.0004-0.00790 m3/s), with more than half of the 16 wells yielding 20-30 gpm (0.001- 0.002 m3/s). Yields from wells along other streams in the county generally produce 20 gpm (0.001 m3/s) or less.

Wells in areas mapped by Mudge and Burton (1959) to include Sanborn Formation and glacial till report yields up to 80 gpm (0.005 m3/s), but 40 (80%) of the 51 sites, including those with the largest yields, obtain all or part of their water from bedrock. Wells in SW SW NW sec. 12, T. 11 S., R. 11 E. (possibly part of a buried drainage), and NW NE NE sec. 20, T. 12 S., R. 13 E., reportedly produce 50 gpm (0.003 m3/s) and 20 gpm (0.001 m3/s), respectively, but others in these unconsolidated deposits generally provide less than 5 gpm (0.0003 m3/s).

At least 13 wells in bedrock in Wabaunsee County (Denne et al., 1990a) report production of 0.5 gpm (0.00003 m3/s) or less. Another 43 wells indicate yields of 0.6-9 gpm (0.00004-0.0006 m3/s). Only 30 wells that obtain all or part of their water from bedrock units produce 10-80 gpm (0.0006-0.005 m3/s). These higher-yielding bedrock wells are scattered throughout the county (including secs. 3 and 10, T. 11 S., R. 10 E.; sec. 21, T. 11 S., R. 11 E.; sec. 35, T. 12 S., R. 8 E.; secs. 9 and 14, T. 12 S., R. 9 E.; secs. 3 and 22, T. 12 S., R. 10 E.; secs. 1 and 27, T. 12 S., R. 11 E.; sec. 3, T. 12 S., R. 12 E.; sec. 3, T. 13 S., R. 9 E.; sec. 14, T. 13 S., R. 10 E.; secs. 9 and 28, T. 13 S., R. 11 E.; sec. 26, T. 13 S., R. 12 E.; secs. 5 and 30, T. 14 S., R. 12 E.; sec. 17, T. 14 S., R. 13 E.; and secs. 2, 13, and 14, T. 15 S., R. 9 E.).

As described by Mudge and Burton (1959), the Americus Limestone Member of the Foraker Limestone, the Neva Limestone Member of the Grenola Limestone, and the Cottonwood Limestone Member of the Beattie Limestone [all of which are in the Council Grove Group (Permian)] are good aquifers in Wabaunsee County. In addition, the Fort Riley Limestone Member and Wreford Limestone of the Chase Group, the Funston, Crouse, Morrill, Red Eagle, and Long Creek Limestones and the Steams and Roca Shales of the Council Grove Group, and the Tarkio Limestone Member of the Wabaunsee Group have local porous to cavernous zones.

Figure 74 shows reported depths to water in Wabaunsee County, but the data are limited by several factors. For example, the water levels may represent unconfined, confined, and/or composites from multiple aquifers, some water levels may reflect nonequilibrium levels in newly constructed or pumped wells, and the water levels were not obtained for a consistent time (neither season nor year). Despite the data limitations, it is apparent that water is very deep in some bedrock wells [e.g., 85-150 ft (26-46 m) in NW SW SE sec. 10, T. 11 S., R. 10 E., NE SW SW sec. 16, T. 11 S., R. 12 E., SW NE NE sec. 3 and NE SW NE sec. 26, T. 12 S., R. 10 E., NE NW NW sec. 28, T. 13 S., R. 11 E., and NE SW NW and SE SW NW sec. 2, T. 14 S., R. 8 E.]. Other wells that receive all or part of their water from bedrock have depths to water that range from 10 ft to 80 ft (3-24 m).

Figure 74--Depth to water in wells and test wells, Wabaunsee County.

Depth to water in wells and test wells, Wabaunsee County.

Data for depths to water in the Sanborn Formation of Mudge and Burton (1959) and glacial drift are limited. Many of the wells that penetrate these unconsolidated deposits also obtain water from the underlying bedrock. For 11 sites water levels range from 10 ft to 50 ft (3-15 m) deep.

The depth to water below the Buck Creek terrace in the Kansas River and Mill Creek valleys ranges from 14 ft to 50 ft (4.3-15 m). Water levels below undifferentiated terraces along the various streams in the county generally are between 10 ft (3 m) and 34 ft (10 m). Except for one value of 4 ft (1 m), depths to water below the Newman terrace in the Kansas River and Wells, Mill, and Hendricks Creek valleys range from 13 ft to 38 ft (4-12 m). A few values indicate that water levels in alluvial deposits are 10-16 ft (3-4.9 m) near the Kansas River and 21-35 ft (6.4-11 m) along Mill Creek.

Water-elevation data indicate that the ground-water levels roughly parallel the land-surface topography, with ground-water flow toward and down the major stream valleys. The average hydraulic gradient is 2.5 ft/mi (0.5 m/km) along the Kansas River and 5-10 ft/mi (0.9-1.9 m/km) along Mill Creek below Alma.

Saturated thicknesses of unconsolidated deposits (determined by subtracting the questionable depth to water from the depth to bedrock at a given site) are shown in fig. 75. The largest saturated thicknesses [up to 68 ft (21 m)] are in the Kansas River valley near St. Mary's (e.g., NE NE NE sec. 24, T. 10 S., R. 11 E., and NE NE SE sec. 20, NE SW NE sec. 21, and NW NW sec. 22, T. 10 S., R. 12 E.). Most values in the alluvial and terrace deposits along the Kansas River are more than 15 ft (4.6 m). The Buck Creek, undifferentiated, and Newman terraces and the alluvium in the Mill Creek valley generally contain 10-30 ft (3-9 m) of saturated material. Along the smaller streams saturated thicknesses range from 0 to 10 ft (3 m), with 18 ft (5.5 m) reported at one site on Mulberry Creek.

Figure 75--Saturated thickness of Pleistocene Deposits, Wabaunsee County.

Saturated thickness of Pleistocene Deposits, Wabaunsee County.

In Wabaunsee County discharge is primarily to streams, springs, seeps, and wells. Seeps and springs are common in outcrops of Quaternary deposits (especially below lenses or layers of sand and gravel), the Fort Riley Limestone Member and Neva limestone member, and Wreford, Funston, Florence, and Cottonwood Limestones, and the Matfield and Steams Shales. Recharge in the county is primarily from precipitation and movement of water from some of the bedrock units to the overlying or adjacent Quaternary deposits.

Wyandotte County

Geology

Although Wyandotte County is dominated by glacial, eolian, and alluvial deposits (fig. 9), bedrock does occur along many stream valleys and in some upland areas [as mapped by Jewett and Newell (1935) and Ward and O'Connor (1983)] (fig. 5). Pennsylvanian rocks exposed in the county include most of the Kansas City Group, all of the Lansing Group, and the lower part of the Douglas Group [Jewett and Newell (1935), with revised terminology from Zeller (1968)]. Limestones (several of which are cherty) and shales are most common, but sandstone of the Stranger Formation (Douglas Group) occurs in much of western Wyandotte County. The rocks dip northwest at an average of 10 ft/mi (1.9 m/km) in the general Prairie Plains homocline, but small folds locally modify the dip (Jewett and Newell, 1935).

As evidenced by numerous glacial striations (see fig. 7), one or more advances of ice moved from 340° to 24° across Wyandotte County (Schoewe, 1941). At least locally, ice may have moved nearly east-west as indicated by striations oriented 290°-295° on the wall of Turkey Creek 0.25 mi (0.4 km) across the county border into Missouri (Jewett, 1934). In Wyandotte County the Kansas River valley apparently limited the southward movement of the glacier(s). Aber (1981, 1982) observed that the reentrant angles in the glacial border and the bends in the Missouri and Kansas rivers at Kansas City may reflect the division between two major lobes of ice, with Dakota ice to the west and Minnesota ice to the east.

In 1935 Jewett and Newell believed that deposits of glacial till in Wyandotte County occurred as isolated remnants on some hilltops and were generally less than 8 ft (2 m) thick. O'Connor and Fowler (1963) found Pleistocene deposits in Wyandotte County that ranged up to 116 ft (35.4 m) thick in areas outside of the Kansas and Missouri River valleys, and they stated that most of these deposits are till. Dufford (1958) mapped some pre-Illinoian sediments on the uplands north of the Kansas River as part of the Menoken terrace.

The youngest deposits in Wyandotte County include loess and alluvium. Loess covers much of the county and is thickest [locally up to 50 ft (15 m) according to Fishel (1948)] along the river bluffs, especially those of the Missouri River. Buck Creek (Illinoian) and Newman (Wisconsin) terraces have been mapped along Kaw Creek and Wolf Creek in southwestern Wyandotte County (Dufford, 1958), but other tributaries have not been mapped in detail. Wisconsin and Holocene alluvium is abundant. Alluvial deposits in the Kansas and Missouri River valleys and tributaries consist of clay, silt, sand, and gravel, with some boulders near bedrock in the larger valleys. Although the deposits generally progress from fine to coarse with depth, lateral and vertical variations are common.

LANDSAT imagery shows striking differences between the surficial deposits in the Kansas River valley compared with those in the Missouri River valley. Falsecolor composite images covering northeastern Kansas (e.g., path 29, row 33, image ID 246716171 from May 3,1976, and image ID 241316185 from March 10, 1976) indicate that the light-toned Kansas River alluvium is better drained (probably coarser near the surface) than the darker-toned (more moist) surficial deposits in the Missouri River valley. Although detailed laboratory studies of sediments would be needed to confirm the differences, Fishel et al. (1953, p. 38) state that in the Kansas River valley from Kansas City to Bonner Springs "several feet of the surficial material is composed largely of silt and clay, but most of it is slightly sandy." Fishel (1948, p. 18) suggested that "much of the alluvium in the Kansas Valley near Kansas City probably is of glacial origin, having been deposited as glacial outwash by the swollen streams that emanated from the melting ice sheets" and that such material would be relatively coarse. In contrast to the Kansas River, the Missouri River above Kansas City may not have developed until post-Kansan time (O'Connor and Fowler, 1963), although it may have developed "as an interlobate drainage during deglaciation" (Aber, 1981, p. 163).

In Wyandotte County the floodplain along the Kansas River [as mapped by Fader (1974)] generally ranges from 1 mi to 1.5 mi (1.6-2.4 km) in width. The Missouri River valley is 2 mi (3 km) wide, as mapped by Emmett and Jeffery (1969). Geologic sections along these two major river valleys are included in the reports by Fishel (1948), O'Connor and Fowler (1963), Emmett and Jeffery (1969), and Fader (1974).

The channels of the Missouri and Kansas rivers are the most prominent features on the bedrock topographic map of Wyandotte County (plate 1). The map was prepared using 385 drill logs, as described by Denne et al. (1990a), the geologic map by Ward and O'Connor (1983), and the surface topographic map with contours at 10-m intervals (U.S. Geological Survey, 1981d).

From the bedrock topographic map it is apparent that a deep, narrow channel underlies the broader main valley near the junction of the modern Missouri and Kansas rivers. In SW SW NW sec. 11, T. 11 S., R. 25 E., the Kansas Highway Commission found that the depth to bedrock is 239 ft (72.8 m) and that the bedrock elevation is 515 ft (157 m). O'Connor and Fowler (1963) described this core, which has 150 ft (46 m) of glacial till below the alluvium. The lower channel cuts through the relatively soft Pleasanton Group, whereas the Kansas River valley is confined by more resistant rocks of the Kansas City Group. The basal till is a gray calcareous clay with local and erratic sand grains, and O'Connor and Fowler believed that the till may have been mistaken for gray shale in other drill holes, including SE SW SE sec. 10, T. 11 S., R. 25 E. [see Denne et al. (1990a)] from Fishel (1948), where, based on their reexamination of samples, depth to bedrock should be greater than 118 ft (36.0 m).

The U.S. Army Corps of Engineers log (obtained from the Missouri Geological Survey) for a test hole in NW sec. 23, T. 11 S., R. 25 E., indicates that bedrock is at a depth of 183 ft (55.8 m) and at an elevation of 576 ft (176 m). Although this drill hole may be in the same buried channel as that in SW SW NW sec. 11, T. 11 S., R. 25 E., it contains sand and gravel rather than till in the lower 150 ft (46 m). O'Connor and Fowler (1963) described the log for a well in the abandoned Turkey Creek valley in nearby Kansas City, Missouri, in which sand and gravel also make up most of the 242 ft (73.8 m) of sediments above bedrock at an elevation of 595 ft (181 m). Because of the nearly east-west striations along Turkey Creek, perhaps these last two wells represent drainage along the southern margin of an ice mass that may have covered SW SW NW sec. 11 and SE SW SE sec. 10, T. 11 S., R. 25 E. Alternatively, the sites may have been associated with two different glacial lobes, such as those suggested by Aber (1981, 1982, 1988a).

O'Connor and Fowler (1963) included a rather detailed explanation for these narrow, deep channels. They believed that the ancestral Kansas River flowed across Wyandotte County (as it does now) and then followed the course of the modern Missouri River. At some time, glacial ice blocked the river in Missouri and caused ponding. The water eventually breached the divide and flowed into Turkey Creek. The channel below the Kansas River may have been scoured at nearly the same time by a subglacial stream, which was subsequently blocked by ice collapse and then filled with glacial till.

In north-central T. 11 S., R. 25 E., and south-central T. 10 S., R. 25 E., several data points suggest the presence of a major buried tributary that flowed southeast toward the Kansas River and its deep underlying channel. Well logs from the hills in SE NE NW sec. 4 and NW NE NW and NW NW NW sec. 10, T. 11 S., R. 25 E., show depths to bedrock of 108-148 ft (32.9-45.1 m) and sand or sand and gravel layers that are 45-76 ft (14-23 m) thick. Similar but thinner deposits are found in T. 10 S., R. 25 E. (e.g., SW SW SW sec. 33 and NE NE SE sec. 32).

Other buried tributaries occur along the northern side of the Kansas River Valley. For example, oil logs for NE SW sec. 10 and SW SW NE sec. 16, T. 11 S., R. 24 E., indicate depths to bedrock of 116 ft (35.4 m) and 81 ft (25 m) and bedrock elevations of 761 ft (232 m) and 779 ft (237 m), respectively; these sites, with abundant sand and gravel, appear to be in former drainages on opposite sides of a small bedrock knob. It is possible that stream piracy has subsequently altered the related modern Mill and Muncie creeks. A buried tributary also appears to drain southward near Betts Creek. Logs for NW SW sec. 24 and SW SW NW sec. 25, T. 11 S., R. 23 E., show depths to bedrock of 70 ft (21 m) and 65 ft (20 m), respectively, with up to 34 ft (10 m) of sand and gravel.

Another buried channel is clearly evident in northwestern Wyandotte County, but delineation of the valley is difficult because it appears to cross or to be coincident with several modern streams (Wolf, Piper, and Honey creeks) and because the depth to bedrock values may be locally erroneous because of sandstone in the area. Viewed together with data and the bedrock topographic maps from Leavenworth County, it appears that the buried valley may have trended generally east-west, perhaps in an ice-marginal position. Flow may have been westerly toward the Stranger Creek drainage system, southerly toward Wolf Creek, and even easterly toward Connor Creek. The buried-channel deposits are significant in terms of thickness and sand and gravel content (e.g., note logs for SW SW SW sec. 14, SE SE NE sec. 15, SW SW NW sec. 18, NW NW NW sec. 19, NW NW NW sec. 20, and NW NE sec. 29, T. 10 S., R. 23 E.).

In Wyandotte County the depth to bedrock (fig. 76) is greatest in the deep, narrow channels that underlie the more recent Kansas River valley [e.g., 239 ft (72.8 m) in SW SW NW sec. 11, T. 11 S., R. 25 E., and 183 ft (55.8 m) in NW sec. 23, T. 11 S., R. 25 E.]. Other large thicknesses of unconsolidated deposits occur in buried tributaries, such as NW NW NW sec. 10, T. 11 S., R. 25 E., with 148 ft (45.1 m) of deposits, and NE SW sec. 10, T. 11 S., R. 24 E., with 116 ft (35.4 m), in the Missouri River valley [e.g., 140 ft (43 m) in NE SE SE sec. 14, T. 10 S., R. 24 E., and NE SE NE sec. 28, T. 10 S., R. 25 E.], and the buried valley in northwestern Wyandotte County, where values range up to 133 ft (40.5 m) in NW NW NW sec. 19, T. 10 S., R. 23 E.

Figure 76--Depth to bedrock, Wyandotte County.

Depth to bedrock, Wyandotte County.

More typical thicknesses (than the maximum values) of alluvial deposits in the Missouri River valley are between 80 ft (24 m) and 125 ft (38 m), whereas in the Kansas River valley they commonly range from 50 ft to 80 ft (15-24 m). Alluvium in the Kansas River valley within 4 mi (6 km) of its junction with the Missouri River is thicker than in upstream areas and generally ranges from 70 ft to 110 ft (21-34 m) thick. In the smaller stream valleys of the county, alluvial deposits are commonly 5-35 ft (2-11 m) thick.

The thickness of glacial, glaciofluvial, and loess deposits in Wyandotte County ranges from 0 to 148 ft (45.1 m). The deposits are thinnest in the southwestern and southeastern parts of the county. Near the glacial limit, two small areas of glacial drift were mapped along the south side of the Kansas River valley by Ward and O'Connor (1983), and two drill holes (SW SE NW and NW NW SW sec. 24, T. 11 S., R. 24 E.) show deposits 48-56 ft (15-17 m) thick with as much as 18 ft (5.5 m) of basal sand and gravel. North of the Kansas River, thicknesses determined from drill holes show a much greater range, with 25% greater than 60 ft (18 m) and 25% less than 21 ft (6.4 m). The largest values, of course, occur along the buried valleys. Thin residual, colluvial, and glacial deposits locally cover areas shown as bedrock on the geologic map.

The total thickness of sand and gravel layers in Wyandotte County (fig. 77) is greatest [146 ft (44.5 m)] in the deep, narrow channel underlying the Kansas River valley in NW sec. 23, T. 11 S., R. 25 E. Other large values occur in the Missouri River valley [e.g., 140 ft (43 m) in NE SE NE sec. 28, T. 10 S., R. 25 E., and 124 ft (37.8 m) in NE SE SE sec. 14, T. 10 S., R. 24 E.]. At most locations in the Missouri River valley values are at least 60 ft (18 m), whereas in the Kansas River valley they are commonly more than 30 ft (9 m). In the buried Kansas River tributaries sand and gravel thicknesses range from 10 ft to 90 ft (3-27 m). The buried drainageways in the northwestern part of the county contain at least 58 ft (18 m) of sand and gravel (SW SW SE sec. 20, T. 10 S., R. 23 E.) and possibly as much as 85 ft (26 m) (SW NW NE sec. 30, T. 10 S., R. 23 E.). Small modern stream valleys (unrelated to the buried channels) generally contain 0-10 ft (0-3 m) of sand and gravel, and thin lenses of sand and gravel occur near the bedrock surface below loess and/or glacial drift at a few localities scattered throughout the county.

Figure 77--Total Pleistocene sand and gravel thickness, Wyandotte County.

Total Pleistocene sand and gravel thickness, Wyandotte County.

Ground Water

In Wyandotte County alluvial deposits provide, by far, the largest ground-water supplies. Well yields (which have not been corrected for diameter or other well-construction characteristics) are given by Denne et al. (1990a) and are shown in fig. 78. Yields range up to 3,500 gpm (0.22 m3/s) in the Missouri River valley (NE SE SE sec. 14, T. 10 S., R. 24 E.) and up to 1,610 gpm (0.102 m3/s) in the Kansas River valley (NW SE NE sec. 22, T. 11 S., R. 25 E.). Mean values are 1,030 gpm (0.0650 m3/s) in the Missouri River valley (based on 18 wells) and 612 gpm (0.0386 m3/s) in the Kansas River valley (based on 42 wells). Fishel (1948) reported similar averages of 980 gpm (0.062 m3/s) for 22 wells in the Missouri River valley and 650 gpm (0.041 m3/s) for 29 wells in the Kansas River valley. Yield data for tributaries are sparse, but 8-45 gpm (0.0005-0.0028 m3/s) can be obtained locally from the Wolf Creek alluvium.

Figure 78--Estimated well yields, Wyandotte County.

Estimated well yields, Wyandotte County.

Although Fishel (1948) believed that glacial deposits in Wyandotte County were above the water table, and many are indeed dry, significant quantities of water can be obtained from the buried valleys in the northwestern part of the county. Yields from the channel deposits there are commonly 7-20 gpm (0.0004-0.001 m3/s), with values up to 90 gpm (0.006 m3/s) reported in sec. 20, T. 10 S., R. 23 E. Yield data for the buried Kansas River tributaries are unavailable, except for a field report of a 108-ft-deep (32.9-m-deep) dry hole in NW NE NW sec. 10, T. 11 S., R. 25 E. Where saturated (e.g., SW SW NW sec. 25, T. 11 S., R. 23 E.; unfortunately, most of the other buried tributary sites do not have water-level measurements), the sand and gravel layers in these deposits should yield a significant quantity of water. One well in the Menoken terrace (NE SW NE sec. 6, T. 12 S., R. 23 E.) indicates that 15 gpm (0.00095 m3/s) can be obtained there. Elsewhere in the county, small supplies of water [generally less than 2 gpm (0.0001 m3/s)] can be obtained locally from glacial deposits.

As in Johnson County, bedrock formations in Wyandotte County commonly yield no water, although they may provide small amounts locally. Fishel (1948) observed that many farm wells on the uplands obtain small water supplies from bedrock (except during dry years) and that limestones that produce water near outcrops include the Stanton, Plattsburg, Wyandotte, Iola, and Dennis Limestones. Based on well data given by Denne et al. (1990a), it appears that the Douglas Group sandstone in western Wyandotte County is the best bedrock aquifer. The log for a well in SW SE SE sec. 17, T. 11 S., R. 23 E., shows a yield of more than 20 gpm (0.001 m3/s) (presumably from the sandstone and possibly from "broken lime"), whereas other wells in sandstone (locally combined with glacial deposits) produce up to 12 gpm (0.00076 m3/s) but more commonly 1-3 gpm (0.00006-0.0002 m3/s). Other bedrock units in the county generally yield less than 0.5 gpm (0.00003 m3/s).

The depth to water in Wyandotte County (fig. 79) is greatest in bedrock wells. The maximum reported value is 200 ft (60 m) in a 276-ft-deep (84.1-m-deep) well in NW NE NW sec. 32, T. 10 S., R. 23 E., but a 100-ft-deep (30-m-deep) well nearby in NW sec. 32, T. 10 S., R. 23 E., had the same surface elevation, the same depth to bedrock, and the same sand layer at 25-27 ft (7.6-8.2 m) but a water depth of 40 ft (12 m). Other bedrock wells with large depths to water include SE NE SW and SE SE SW sec. 19 and NW NE NE sec. 30, T. 11 S., R. 23 E., where values range from 142 ft to 180 ft (43.3-54.9 m). The water levels in other bedrock wells range from 7 ft to 50 ft (2-15 m).

Figure 79--Depth to water in wells and test wells, Wyandotte County.

Depth to water in wells and test wells, Wyandotte County.

In the glacial buried valley in northwestern Wyandotte County, depths to water are most commonly either 17-32 ft (5.2-9.8 m) or 55-79 ft (17-24 m). The full range of values, however, is 6-90 ft (2-27 m). In other glacial deposits throughout the county (where not dry), water levels are generally 24-45 ft (7.3-14 m), although they range from 4 ft to 55 ft (1-17 m).

Water levels are most consistent in the alluvial deposits. Along Wolf Creek two measurements were 15 ft (4.6 m). In the Missouri River valley the depth to water varied from 8 ft to 35 ft (2-11 m), with 27 (85%) of 32 values falling in the range 10-22 ft (3-6.7 m). Ninety-seven water-level measurements in the Kansas River alluvium indicated depths from 6 ft to 49 ft (2-15 m), with 76 (78%) in the range 20-40 ft (6-12 m). Where pumpage from these valleys is heavy, as it is near Kansas City, some of these water levels may reflect cones of depression rather than static surfaces.

The saturated thickness of unconsolidated deposits in Wyandotte County (fig. 80) is greatest in the Missouri River valley, where water levels are generally shallow and bedrock is deep. The saturated thicknesses there are commonly much greater than 60 ft (18 m), and the maximum values in the county [101-121 ft (30.8-36.9 m)] occur in NE SE SE sec. 14, T. 10 S., R. 24 E., and in SW NW SE and SW NW sec. 27 and NE SE NE sec. 28, T. 10 S., R. 25 E. In the Kansas River valley, saturated thicknesses commonly range from 40 ft to 90 ft (12-27 m) within 4 mi (6 km) of the junction with the Missouri River and from 25 ft to 50 ft (7.6-15 m) further upstream. It should be noted that no water-level measurements (and therefore no saturated thickness data) are available for the thick deposits in SW SW NW sec. 11 and NW sec. 23, T. 11 S., R. 25 E. In Wolf Creek the saturated thickness of the alluvium at two sites is 10 ft (3 m) and 19 ft (5.8 m).

Figure 80--Saturated thickness of Pleistocene deposits, Wyandotte County.

Saturated thickness of Pleistocene deposits, Wyandotte County.

The saturated thickness of glacial deposits is greatest in the buried valley in T. 10 S., R. 23 E., where values are commonly between 10 ft (3 m) and 60 ft (18 m). Along the northern bank of the Kansas River several sites have 13-41 ft (4.0-12 m) of saturated material, whereas on the southern side one drill hole indicates 11 ft (3.4 m). Elsewhere in the county small saturated thicknesses of glacial deposits and/or loess occur locally.

No attempt was made to contour water-level elevations because of discontinuities, multiple aquifers, and other problems with water-level measurements, as previously discussed. It is apparent, however, that elevations of water in the bedrock wells where water is deep (e.g., SE NE SW and, SE SE SW sec. 19 and NW NE NE sec. 30, T. 11 S., R. 23 E.) are just slightly higher than those in the Kansas River alluvium, whereas water elevations are commonly 150 ft (46 m) higher in most bedrock and glacial wells to the north.

In the Kansas River valley the water table generally declines from 753 ft (230 m) in the southwest to 710 ft (220 m) near the junction with the Missouri River. Fader's (1974) map of the 1967 water table in the Kansas River valley indicates an average hydraulic gradient of 1.5 ft/mi (0.3 m/km) across Wyandotte County. Flow generally is toward the river, except where pumpage locally reverses the gradient or during flooding. Elevations along the Missouri River range from 702 ft to 735 ft (214-224 m). A contour map of the piezometric surface in the Missouri River valley in January 1968 (Emmett and Jeffery, 1969) indicates an average hydraulic gradient of 2 ftlmi (0.4 m/km) in Wyandotte County.

Although local water-quality problems occur in alluvial deposits and in deep bedrock formations, large quantities of water can be obtained from glacial buried valleys and the Kansas and Missouri River valley deposits in Wyandotte County. Pumpage near Kansas City is already heavy in many areas, but additional water supplies are still available.

Aquifer tests on four wells in the Kansas River valley that were pumped at 525 gpm (0.0331 m3/s), 560 gpm (0.0353 m3/s), 610 gpm (0.0385 m3/s), and 740 gpm (0.0467 m3/s) indicate transmissivity values of 18,200-32,000 ft2/d [136,000-240,000 gpd/ft (1,690-2,980 m2/d)] and storage coefficients of 0.11-0.18 (Fader, 1974). Based on two pump tests, alluvium in the Missouri River valley locally has a coefficient of permeability (or hydraulic conductivity) of 3,000 gpd/ft2 (120 m/d) (Fishel, 1948), which would give a transmissivity of 300,000 gpd/ft (4,000 m2/d) for a 100-ft (30-m) saturated thickness.

Fishel (1948) reported that the average specific capacities of wells in the Kansas and Missouri River valleys were 60 gpm/ft (0.01 m2/s) and 180 gpm/ft (0.037 m2/s), respectively. Calculations from data in table 9 of Fishel's report indicate a range of 13-119 gpm/ft (0.0026-0.0246 m2/s) [for 14 wells pumped from 200 gpm to 1,800 gpm (0.01-0.11 m3/s) in the Kansas River alluvium] and 55-375 gpm/ft (0.011-0.0776 m2/s) [for 18 wells pumped from 80 gpm to 1,580 gpm (0.005-0.0997 m3/s) in the Missouri River deposits].

Recharge in Wyandotte County is predominantly from precipitation. Discharge is primarily to the rivers (except during floods) and to wells.


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Kansas Geological Survey, Geohydrology
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