Sedimentary rocks of Paleozoic and Cenozoic ages overlie the basement complex of Precambrian age in Neosho County. The subsurface Paleozoic rocks of Cambrian, Ordovician, Devonian(?), Mississippian, and Pennsylvanian ages have an average thickness of 2,100 feet, as shown by logs and drill cuttings from oil and gas wells in the area.
The Precambrian rocks of Kansas, as shown by drill cuttings from wells, consist of quartzite, schist, slate, marble. prophyry, and granite. The Precambrian surface in Neosho County slopes to the west from about 1,000 feet below sea level at the Crawford County line to about 1,200 feet below sea level at the Wilson County line. An apparent ridge of low relief on the Precambrian surface trends east-west through central Neosho County (Jewett, 1954, fig. 9).
The Lamotte Sandstone of Late Cambrian age unconformably overlies the Precambrian rocks and is conformable with the overlying Bonneterre Dolomite. The Lamotte is an unsorted quartzose sandstone with an arkosic zone in the basal part. The sandstone is thought to be present and to have a thickness of less than 20 feet throughout Neosho County. In the Dack et al. #1 Arnett well (NE NW SW sec. 8. T 30 S, R 18 E) in southwestern Neosho County, 65 feet of Bonneterre Dolomite of Late Cambrian age underlies the Arbuckle Group and is conformable with it.
Cambrian and Ordovician Systems
In Neosho County four subdivisions of the Arbuckle Group of Late Cambrian and Early Ordovician ages are recognized. The Eminence Dolomite of Late Cambrian age is 39 feet thick in the Dack et al. #1 Arnett well. The subdivisions of rocks of Early Ordovician age in the well are: the undivided Gasconade Dolomite and Van Buren Formation with a slight thickness of the Gunter Sandstone Member at the base, 295 feet; the Roubidoux Formation, 30 feet; and the undifferentiated Cotter and Jefferson City dolomites, 483 feet. In Neosho County, Upper Ordovician rocks and Silurian rocks are missing (Lee and Merriam, 1954).
Devonian or Mississippian System
The Chattanooga Shale of Late Devonian and Early Mississippian age is represented by 5 feet of black shale in Neosho County. The shale is conformably overlain by rocks of Early Mississippian (Kinderhookian) age.
Pennsylvanian rocks in Neosho County are represented by the Desmoinesian and Missourian stages. The Desmoinesian Stage comprises the Cherokee Group and Marmaton Group. Rocks of the Pleasanton Group and the Kansas City Group and part of the Lansing Group represent the Missourian Stage.
No rocks older than the Pawnee Limestone of the Marmaton Group crop out in the county. Test holes in the Neosho River valley in T 31 S. R 21 E. Labette County, 3 miles south of the Neosho and Labette county line, encountered limestone and shale members of the Fort Scott Limestone.
[Note: The stratigraphic classification used in this report is that of the State Geological Survey of Kansas and does not necessarily follow the nomenclature of the U. S. Geological Survey.]
The terminology used to describe the bedding of the several geologic units is that proposed by McKee and Weir (1953) and modified by Ingram (1954). Grain sizes used in the descriptions of sandstones, siltstones, and alluvial deposits are those given in the Wentworth Grade Scale as modified by Dunbar and Rodgers (1957, p. 161). The texture of limestones has been described according to an adaptation of the Wentworth Grade Scale proposed by Payne (1942, p. 1706). A graphic column of outcropping rocks in the county is shown in Figure 3.
Figure 3--Graphic column of outcropping rocks, Neosho County, Kansas.
Pennsylvanian System--Middle Pennsylvanian Series
Desmoinesian Stage--Marmaton Group
The Pawnee Limestone is the oldest rock that crops out in Neosho County. Only the Laberdie Limestone Member of the Pawnee is seen in the county.
Laberdie Limestone Member
Medium-bedded to thick-bedded, light-gray, medium-crystalline limestone about 20-feet thick comprises the Laberdie in Neosho County. Massive colonies of the coral Chaetetes are abundant near the top of the Laberdie. Gray clay-shale partings occur between the limestone beds. The only outcrop of the Laberdie found in Neosho County is in the SE sec. 31, T 30 S, R 21 E.
The Bandera Shale, which is composed of three lithologic units, ranges in thickness from about 60 feet near the Crawford county line to about 90 feet at the Labette county line. Excellent exposures of the formation are found along the Neosho River in the southeastern part of the county.
The lower unit of the Bandera is a brownish-yellow to dark-brown, medium-bedded quartzose sandstone with predominantly iron-oxide cement. Thickness of this sandstone ranges from 30 to 45 feet. Individual sandstone beds have an average thickness of about 1 foot and are separated by brownish-yellow, sandy shale partings. In some localities near the southern boundary of the county, the interbedded, sandy shale is the dominant lithology. Where this occurs the sandstone beds are about 3 inches thick. The sand is moderately sorted with a grain size ranging from less than 0.1 mm to 1.0 mm in diameter. The base of the Bandera is covered by terrace and alluvial deposits in the Neosho River valley except in SE sec. 31, T 30 S, R 21 E, where the underlying Pawnee Limestone is exposed.
Overlying the sandstone is a dark brownish-orange, medium-bedded, sandy shale that ranges from 20 to 30 feet in thickness. Current-formed ripple marks are common on bedding planes. The sand grains are predominantly of quartz, moderately rounded, and generally less than 0.5 mm in diameter.
The upper portion of the Bandera is a dark-gray, blocky clay shale ranging in thickness from 10 to 15 feet. Marine fossils such as brachiopods and crinoid columnals are sparsely distributed at the top of this unit in a 0.5-foot yellow clay-shale zone.
The Altamont Limestone in Neosho County comprises two limestone members separated by a shale member. In ascending order, the members are: Amoret Limestone, Lake Neosho Shale, and Worland Limestone. The formation is as much as 30 feet thick in some areas, but the average thickness is about 20 feet. Excellent exposures of the Altamont occur in the southeastern part of the county where it forms prominent bluffs along the west side of the Neosho River valley.
Amoret Limestone Member
The Amoret Limestone Member in Neosho County consists of one bed of massive limestone or, locally, of two limestone beds separated by a thin shale. The two limestone beds are best exposed in the vicinity of Neosho County State Lake. Near the lake the lowermost limestone is a wavy-bedded, light-gray limestone about 10 feet thick that weathers tan on the outcrop. Jewett (1941, p. 332) reported the brachiopod Mesolobus in the basal portion of this bed. A zone of light-gray clay shale about 1 foot thick separates the lower limestone from an overlying massive, light-gray to bluish-brown limestone about 5 feet thick. The texture of the upper limestone ranges from finely crystalline to marly. Locally, a 0.5-foot gray shale bed is found about 1.5 feet below the top of this limestone. Crinoid columnals and brachiopod fragments are the most common fossils. Northeast of the lake along the outcrop of the Altamont, a 3-foot massive-bedded limestone is the only bed representing the Amoret.
Lake Neosho Shale Member
The Lake Neosho Shale Member is well exposed only in the vicinity of the type section near the Neosho County State Lake. In this area the Member consists of about 3 feet of black fissile shale. Locally, discontinuous lenses of dark-blue, blocky shale occur at the top. Oblate, phosphatic concretions about 0.5 inch thick and uniformly about 1.5 inches in their longest dimension are common throughout the bed. Northeast of the lake, along the line of outcrop of the Altamont where the limestone members are not everywhere well exposed, the approximate stratigraphic position of the Lake Neosho Shale may be inferred from the presence of the phosphatic concretions weathered from the outcrop.
Worland Limestone Member
The Worland is a light-gray, very finely crystalline, massive limestone, which weathers almost white on the outcrop. Average thickness of the Member is about 9 feet. Locally, the upper 3-4 feet of the Worland is thin bedded with gray, clay-shale breaks. Transparent void-filling calcite is found throughout the Member but is more common in the upper, thin-bedded limestone. Fossils such as the brachiopod Mesolobus and crinoid columnals which have been replaced by crystalline calcite are common. Where the Worland is composed of a single massive bed, two sets of vertical joints enlarged by solution activity are a conspicuous feature. The major joint set has an average bearing of N 40° E and the minor set about N 45° W. The Worland is the prominent escarpment-forming member of the Altamont Limestone.
Yellowish-brown to tan shale is the dominant lithology of the Nowata Shale. The thickness of the unit ranges from about 16 feet in the vicinity of Neosho County State Lake to a maximum of 22 feet east of St. Paul. The basal part of the Nowata is commonly a zone of yellowish-brown clay shale about 9 to 15 feet in thickness. Thin flags of very fine-grained brown sandstone are found throughout this zone. The upper 5 to 7 feet of the formation is light-tan, calcareous clay shale. Lenses of very fine-grained quartzose sandstone about 0.5-inch in thickness are interbedded in the shale. This light-tan shale grades downward into a zone of yellow, calcareous clay shale about 1.5 feet thick. Dark-gray, very finely crystalline limestone nodules occur locally in this yellow shale.
The Lenapah Limestone in Neosho County consists of two limestone members separated by a shale member. The members are, in ascending order, the Norfleet Limestone, Perry Farm Shale, and Idenbro Limestone. Locally, the Idenbro Limestone and the Perry Farm Shale members as well as part of the Norfleet Limestone Member have been removed by pre-Missourian erosion. In the southern part of T 28 S, near the Crawford county line, the Lenapah Limestone and the overlying Holdenville Shale have been completely removed, and rocks of the Pleasanton Group rest disconformably upon the Nowata Shale. In the same area, the Lenapah is represented by a thin zone of dark-gray, fine-grained, unfossiliferous limestone rubble, which is probably the basal part of the Norfleet Member. No complete section of the Lenapah Limestone was found at any one outcrop in Neosho County; however, each member occurs in at least one locality. Although only 5 to 10 feet of the Lenapah can be seen at any one outcrop, a total thickness of 20 feet for the formation can be inferred from drillers' logs.
Norfleet Limestone Member
In Neosho County the Norfleet Limestone Member is represented by a thin-bedded, dark-gray, tan-weathering, finely crystalline fossiliferous limestone bed that ranges in thickness from 0.5 foot to 7 feet. Locally, where the Norfleet is as thick as 7 feet, small productid brachiopods and broken crinoid columnals are abundant in the basal part of the Member and light-gray chert nodules are distributed sparsely throughout the upper 2 feet. Where the Norfleet is represented by about 0.5 foot of limestone, the bed is predominantly crinoidal. The crinoidal bed is probably equivalent to the lowermost portion of the Norfleet observed elsewhere.
In some areas the Norfleet was not deposited and the Perry Farm Shale Member directly overlies the Nowata Shale. Locally, the Perry Farm Member contains nodular limestone, as does the upper part of the Nowata Shale, and it is difficult to define the contact between them. However, as the upper part of the Nowata contains some sandy shale interbedded with the limestone nodules, the contact probably lies in the zone of gradation from the sandy shale to the overlying clay shale.
Perry Farm Shale Member
The Perry Farm Shale Member is not well exposed in Neosho County. It is generally a tan to light-gray calcareous shale that contains dark-gray, very finely crystalline limestone nodules. The thickness of the shale ranges from about 0.8 foot to 4 feet.
Idenbro Limestone Member
The Idenbro Limestone Member is the most conspicuous member of the Lenapah where it is present at the outcrop. Average thickness of the Idenbro in Neosho County is about 6 feet. The dominant lithology of the Member is a medium-crystalline to semi-lithographic light-gray limestone that weathers to a grayish-white on the outcrop. Some coarsely crystalline. translucent, void-filling calcite is present near the base. In some outcrops the lower 1.5 feet is a thin-bedded limestone with thin (0.25-inch) gray, clay-shale partings.
Vertical joints, a conspicuous feature of the Idenbro, have been widened by solution so that the limestone weathers into blocks 5 to 8 feet in length, 3 to 4 feet in width, and about 6 feet in thickness. The upper surface of the Member, where it is exposed, develops a characteristic hummocky, pitted appearance. Large productid brachiopods are common throughout the limestone.
The Holdenville Shale occurs only locally in Neosho County. Thickness of the formation, where present, ranges from a few inches to as much as 15 feet. At the base of the Holdenville a 1-foot bed of greenish-gray, limonite-stained clay shale occurs. At most outcrops of the formation in Neosho County, a 0.4-foot coal bed overlies the thin, basal clay-shale zone. Above the coal is an 0.8-foot bed of black, carbonaceous shale. The black shale contains abundant fragments of the fossil plant Calamites. Locally, the black shale and plant fossils are silicified, and finely crystalline quartz is found on the bedding planes. The Holdenville above the black shale is yellowish-gray, variegated clay shale which weathers to a very pale greenish gray.
Pre-Missourian erosion has removed the Holdenville in many localities in the county and rocks of the overlying Pleasanton Group rest on the Lenapah Limestone or lower beds.
Pennsylvanian System--Upper Pennsylvanian Series
Missourian Stage Pleasanton Group
The Pleasanton Group comprises three formations which are, in ascending order: Seminole Formation, Checkerboard Formation, and Tacket Formation (Jewett, et al., 1964). Thickness of the Pleasanton Group at the outcrop in Neosho County ranges from 30 feet near the Labette County line in T 30 S, R 20 E to 60 feet in T 27 S, R 21 E.
The Seminole Formation of the Pleasanton Group comprises two members which are, in ascending order, the Hepler Sandstone and South Mound Shale. The thickness of the formation in Neosho County ranges from 1 foot to 4 feet.
Hepler Sandstone Member
The Hepler Sandstone Member is a blanket-type deposit that is present nearly everywhere in eastern Kansas as the basal unit of the Missourian Stage. Thickness of the Member in Neosho County ranges from 0.3 foot to 3 feet. The dominant lithology of the Hepler is a moderately sorted, very fine-grained to fine-grained quartzose sandstone that is well-cemented with calcium carbonate. The Member is generally reddish-brown on weathered surfaces but in fresh exposures it is gray to yellowish-gray. Silt is a minor constituent of the Hepler in Neosho County. The sandstone is generally thin bedded to very thin bedded, but locally, as in the creek bed in the southern half of sec. 18, T 30 S. R 20 E. the Hepler is an homogeneous unit about 0.75 foot thick.
The Hepler was deposited upon an erosional surface formed during pre-Missourian time. This surface has a local relief of about 30 feet, as inferred from elevations of the contact of the Hepler with underlying beds.
South Mound Shale Member
The South Mound Shale Member in Neosho County is a gray clay shale. Locally, the basal part of the Member is slightly silty. The thickness of the South Mound is uncertain in much of the county, as the overlying Checkerboard Limestone is missing and the South Mound Shale Member is overlain by the lower shale member of the Tacket Formation. Where the Checkerboard is present, as in the southern half of the county, the Member can be differentiated, and the thickness ranges from about 0.3 foot to 2 feet.
South of Neosho County in Labette and Montgomery counties, the Checkerboard Limestone comprises two unnamed limestone members separated by an unnamed shale member (Jewett, et al., 1964). In Neosho County, only the lower member is found locally at the outcrop south of sec. 28, T 29 S, R 20 E.
The Checkerboard in Neosho County ranges in thickness from about 0.4 foot to 2 feet. Where the thickness is about 2 feet, as in T 29 S, R 20 E, the formation consists of medium-gray, brown-weathering, thin-bedded limestone. Bryozoan fragments, crinoid columnals, brachiopods such as Composita and Derbyia, and other fossils are so abundant that the bed is almost a coquina. In sec. 10, T 30 S, R 20 E to the south of the above outcrop, the bed is a 0.4-foot, brownish-yellow, very silty limestone that contains abundant Composita and Derbyia.
The Tacket Formation, the most conspicuous part of the Pleasanton Group in Neosho County, forms gentle slopes below the overlying Hertha Limestone. The Formation consists of two unnamed shale members separated by an unnamed limestone member and ranges in thickness from about 25 feet in the south-central section of the county near the Labette County line to nearly 60 feet in the northeastern part of the county. Where the Checkerboard Limestone is absent, as north of T 29 S, R 20 E, the South Mound Shale Member of the Seminole Formation is not differentiated, and rocks of the Tacket Formation apparently rest directly upon the Hepler Sandstone Member of the Seminole Formation.
Lower unnamed shale member
Thickness of the lower shale member ranges from about 20 feet in the southern part of Neosho County to nearly 40 feet in the northern part of the outcrop area; the average thickness is about 25 feet. Dark-gray to black, fissile to blocky, carbonaceous, clay shale makes up nearly all the member.
In northeastern Neosho County, a 2-foot, medium-bedded, gray, brown-weathering, poorly sorted, quartzose sandstone is found locally about 25 feet above the top of the Hepler Sandstone. The sandstone contains fragments of brachiopods and remains of plants. In the SW sec. 27, T 27 S, R 21 E, a 0.3-foot, gray silty limestone is found above the sandstone. Crinoid columnals and fragments of small brachiopods are abundant in this limestone. Locally, in the northern part of the outcrop, a thin zone of black fissile shale containing phosphatic nodules is found at the top of the member.
Middle unnamed limestone member
The limestone member of the Tacket Formation is the most persistent of all the units in the Pleasanton Group. This member consists of 2 feet of dark-gray, tan-weathering, very fine-grained, ellipsoidal limestone nodules. The nodules range in size from about 0.3 foot to as much as 2 feet along their longest axis. The average size of the nodules increases from north to south in Neosho County. However, at any one outcrop these nodules are about the same size. Megafossils are rare, but Emery (1962, p. 34) has found fragments of arenaceous foraminifers in several nodules.
Upper unnamed shale memberDark-gray to black, light-gray-weathering blocky clay shale is the dominant lithology of the upper member of the Tacket Formation. Thickness of the member ranges from about 6 feet in the southern part of the county near the Labette County line to about 15 feet in the northeastern part near the Crawford County line.
In some localities, especially in the southern part of the outcrop, a 1-foot zone of light-gray, yellow-weathering, silty shale is found at the top of the member just below the Hertha Limestone. Phosphatic nodules as much as 0.5 inch in diameter are common in the black shale. Fossils in the member consist of a few casts of a small pelecypod and a few dwarfed specimens of dictyoclostid brachiopods.
Missourian Stage--Kansas City Group (Bronson Subgroup)
The Hertha Limestone is a prominent escarpment-forming unit in Neosho County. Thickness of the formation ranges from about 7 feet in the northeastern part of the outcrop in the area south and east of Kimball to about 14 feet at the type section north of the old townsite of Hertha in the south-central part of the county. The Hertha Limestone comprises three members which are, in ascending order, the Critzer Limestone, Mound City Shale, and Sniabar Limestone.
Critzer Limestone Member
The Critzer is a medium-crystalline, bluish-gray limestone with an average thickness of about 3 feet. Locally, in the central part of the county, the Critzer is a silty, yellowish-brown limestone in which crinoid remains are common. In the northeastern part of the county, the Critzer and the overlying Mound City Shale were apparently not deposited, and the Sniabar rests on rocks of the Pleasanton Group. The Critzer Member supports the prominent escarpment formed by the Hertha south of T 27 S.
Mound City Shale Member
The Mound City Shale Member is very thin or absent in outcrops of the Hertha Limestone in Neosho County. At the type section of the Hertha, NE sec. 20, T 29 S, R 20 E, the Mound City is represented by 1.5 feet of silty shale. There, the upper 0.5 foot is a light-gray shale that grades abruptly downward into black platy shale. South of the type section of the Hertha, the Mound City thickens. Core samples taken by the Kansas Highway Department along U. S. 59 south of Erie show the Mound City to be about 6 feet of black platy shale. In the northeastern part of the county the Mound City is missing and the Sniabar Limestone Member of the Hertha rests directly on rocks of the Pleasanton Group.
Sniabar Limestone Member
Medium-gray, tan-weathering, finely crystalline, medium-bedded limestone is characteristic of the Sniabar Member of the Hertha. Average thickness of the Member is about 7 feet, although in the northern part of the county the Member attains about 4 feet. Chert nodules, a prominent feature of the Sniabar in the northern part of the county, weather locally from the limestone and compose nearly the entire outcrop. Stringers of very finely crystalline calcite are abundant and brachiopods are fairly common in the lower part of the Member.
The Ladore Shale consists predominantly of medium to dark-gray clay shale throughout its outcrop area in Neosho County. The thickness of the formation is uniformly about 40 feet. Oblate, dark-gray to dark-bluish-gray, argillaceous limestone concretions, 0.5 inch to 3 inches in thickness, are found in the lower 36 feet of the shale. Locally, these concretions are the dominant lithology in the Ladore. A few miles south of Erie, these concretions form residual deposits which resemble the mounds of Tertiary(?) chert gravel found to the northwest along the bluffs bordering the Neosho River valley. The concretions in these deposits are extensively weathered and much of the calcium carbonate has been removed, leaving a soft light yellowish-brown clay. Samples from test holes augered through the alluvium of the Neosho River valley indicate that the basal 5 feet of the Ladore is a light-gray, silty shale.
Above the zone of limestone concretions is a 3-foot yellow clay shale with interbedded 0.5- to 1.5-inch limestone lentils. An 0.8-foot zone of yellowish-brown, sandy shale is commonly found at the top of the Ladore just below the overlying Middle Creek Limestone Member of the Swope Limestone. Many brachiopods, fenestrate bryozoan fragments, and crinoid columnals are found in this shale.
The Swope Limestone comprises the following members, in ascending order: Middle Creek Limestone, Hushpuckney Shale, and Bethany Falls Limestone. The formation ranges in thickness from about 7 feet to nearly 13 feet.
Middle Creek Limestone Member
The Middle Creek Limestone Member is a 3-foot bed of medium to dark-gray, finely crystalline limestone. Fragments of brachiopods, crinoids, and bryozoans largely replaced by coarsely crystalline calcite occur sparsely throughout the Member. In a southwesterly direction along the strike of the Swope from T 28 S, R 20 E, the Middle Creek Member is missing at many outcrops. Where the Middle Creek is absent, the Hushpuckney Shale Member is also missing, and the Bethany Falls Limestone Member is found in contact with the underlying Ladore Shale.
Hushpuckney Shale Member
Dark-gray to black, fissile shale is characteristic of the Hushpuckney Shale Member in Neosho County. Small amounts of pyrite may be found between laminae of the shale. The average thickness of the Hushpuckney is about 3 feet. In the south-central and southern part of the county, the Member is locally absent.
Bethany Falls Limestone Member
The Bethany Falls Limestone is the only member of the Swope that is everywhere present along the outcrop. Massive, very finely crystalline, light-gray limestone is characteristic of the Member throughout most of Neosho County. However, in the central part of the county the Bethany Falls is a medium-crystalline, light-brown, tan-weathering limestone. The Member ranges in thickness from about 7 feet in the northeastern and central part of the county to more than 10 feet in the south-central part near the Labette County line.
Sandy shale and very thin-bedded to thick-bedded sandstone is the dominant lithology of the Galesburg Shale in Neosho County. In addition, the Dodds Creek Sandstone Member is present at the base of the formation in most localities. The overall thickness of the formation ranges from about 20 feet in the northeastern part to as much as 80 feet in the central and southern parts of the county. Most of the change in thickness is the result of the pronounced thickening of the Dodds Creek Sandstone Member.
Very thick-bedded, fine-grained to very fine-grained, buff to brown, slightly-rounded, quartzose sandstone is characteristic of the Dodds Creek. The grains are normally cemented by silica or silty clay, and all exposures of the sandstone appear to be casehardened by iron oxide. Small-scale cross bedding occurs in the sandstone in the northern part of the outcrop. The Member thickens from an average of about 20 feet in T 27 S, R 20 E to nearly 60 feet in T 30 S, R 19 E.
Only the upper few feet of the part of the Galesburg Shale that overlies the Dodds Creek Sandstone Member is well exposed in Neosho County. In T 27 S, R 20 E the upper 4 to 6 feet of the formation consist predominantly of light-gray, blocky, clay shale. Plant fossils, tentatively identified as Alethopteris, are found on the bedding planes. Southwest of T 27 S, R 20 E, along the outcrop, the clay shale apparently grades laterally into brownish-red, sandy shale and thin-bedded, brown sandstone that increases in thickness to about 20 feet in the south-central part of the county.
The Dennis Limestone in Neosho County consists of three members. They are, in ascending order: the Canville Limestone, the Stark Shale, and the Winterset Limestone. The formation ranges in thickness from about 6 feet to as much as 70 feet.
Canville Limestone Member
The Canville Limestone Member is composed of a single massive, medium- to light-gray, finely crystalline limestone that weathers to a light dove-gray color. Widely spaced vertical joints are common in the Member. Thickness of the unit averages about 3 feet and locally is as much as 5 feet. Where the increased thickness is observed at the outcrop, the Canville has apparently been deposited in slight depressions in the upper surface of the underlying Galesburg Shale. The limestone is relatively unfossiliferous with only sparsely distributed brachiopod, crinoid, and bryozoan fragments found near the base of the unit at some outcrops.
Stark Shale Member
Black, carbonaceous, blocky to fissile, clay shale composes the Stark Shale Member in Neosho County. In some outcrops a 0.5-foot zone of medium- to light-gray, clay shale is found above the black shale. Very finely crystalline pyrite is commonly found on bedding planes in the black shale. Closely-spaced vertical joints give a columnar appearance to the black shale at some localities. The average thickness of the Member is about 3 feet. Locally, along the outcrop in Neosho County, the thickness is as much as 5 feet. Thickening of the upper clay shale zone from 0.5 to as much as 2 feet is the apparent reason for the change in the overall thickness of the Member.
Winterset Limestone Member
The Winterset Limestone Member crops out over about 20 percent of the surface of Neosho County (Pi. 1). Maximum thickness of the Member is about 60 feet although in most localities the thickness is about 35 feet. Where pre-Chanute erosion has cut into the Winterset, as seen in the bluff along Neosho River east of Chanute, the Member is represented only by a zone of limestone rubble about 1 foot thick.
For purposes of discussion, the Winterset may be divided into a lower, very thick-bedded zone and an upper, thin-bedded to medium-bedded zone. The lower thick-bedded portion of the Winterset is a massive, medium-gray, finely crystalline limestone with an average thickness of about 20 feet. Weathered surfaces of the rock are light-gray or almost white. Fossils such as the brachiopod Echinaria, crinoid columnals, and fragments of fenestrate bryozoans are common. White, nodular chert is abundant in the limestone; and although the chert is not bedded, some horizons are locally almost entirely chert. Commonly an oolitic zone from 3 to 5 feet in thickness is found at the top of the unit.
The upper thin-bedded to medium-bedded portion of the Winterset is a light-gray to brownish-gray limestone that ranges in thickness from about 15 feet to as much as 30 feet. The limestone is very finely crystalline and almost semi-lithographic in texture. Very coarsely crystalline, void-filling calcite is found throughout the thin-bedded zone. Dark brownish-yellow mottling, probably due to oxidation of included iron, is conspicuous on broken surfaces of the light-tan fragments found in the zone of weathering. In some localities part of the upper zone appears to be composed of algal material. Dark-gray undulating plates of fine-grained calcite, 1 to 3 inches long and about 0.1-inch thick, are found throughout the rock oriented approximately parallel to the bedding planes. These stringer-like forms are slightly darker than the matrix in which they are found. Harbaugh (1959) has discussed the Plattsburg Limestone, which is apparently quite similar to the Winterset with respect to the occurrence of algal remains. Some replacement of calcite by dolomite has occurred in the algal zone. The dolomite is bone white to light pink in color. Distorted dolomite rhombohedrons are seen in some hand specimens.
In the northeastern quarter of the county, a 3-foot bed of light-gray, silty, clay shale is found approximately 12 feet above the base of the thin-bedded zone of the Winterset. This shale bed is well exposed only in the area around and to the northeast of Stark where it weathers into small blocks or cubes about 1 inch square. Laminae of sandy shale are interbedded with the clay shale. These laminae are less easily weathered than the clay shale and stand out in relief on the face of the outcrop.
Above the shale, the Winterset contains several oolitic horizons. At most localities the oolites are in the upper 3 to 4 inches of the limestone slabs. Small-scale cross bedding of the oolites is seen at some outcrops.
Echinaria is abundant in the upper medium-bedded part of the Winterset; however, its average size is somewhat less than in the lower massive zone. Other marine fossil remains such as crinoid columnals and bryozoan fragments are about as abundant as in the lower zone. White and gray chert nodules are more abundant in the thin-bedded part than in the massive, lower part of the Winterset. At some outcrops of the Winterset in northeastern Neosho County, residual chert deposits weathered from the upper zone are as much as 5 feet in thickness.
Missourian Stage--Kansas City Group (Linn Subgroup)
Five members ordinarily make up the Cherryvale Shale. They are, in ascending order: the Fontana Shale, the Block Limestone, the Wea Shale, the Westerville Limestone, and the Quivira Shale. In Neosho County, the Westerville Limestone Member is missing, and a limestone tentatively identified as the Block Limestone Member is seen only in the northeastern part of T 30 S, R 18 E.
A greenish-gray, blocky, clay shale about 15 feet thick lies at the base of the Cherryvale throughout most of the county. The shale is not well exposed except in T 30 S, R 18 E. The shale is overlain in T 30 S, R 18 E by a dark-gray, thick-bedded, fine-grained limestone about 3 feet thick, which is probably an equivalent of the Block. Two lenticular 0.1-foot coal beds separated by about 0.5 foot of yellow, sandy, clay overlie the basal clay shale zone in the southern part of T 29 S, R 18 E. Elsewhere in the county, a fine-grained, thick-bedded, quartzose sandstone occurs above the basal clay shale zone in the approximate stratigraphic position of the Block Limestone Member. Above the Block, the Cherryvale is predominantly a light-tan to reddish-brown, thin-bedded, sandy shale. In T 28 S, R 18 E a massive bed of sandstone about 3 feet thick occurs about 10 feet below the overlying Drum Limestone. In T 28 S, R 18 E, 0.5 foot of fossiliferous, yellow clay shale is at the top of the Cherryvale and directly underlying the Drum Limestone. Large crinoid columnals (0.5-0.75 inches in diameter), brachiopod fragments, and fenestrate bryozoan fragments are common in this shale.
East of the Neosho River, in T 27 S, R 18 E and T 27 S, R 19 E, pre-Chanute erosion has removed the Cherryvale and the overlying Drum Limestone, and the Chanute Shale rests directly upon the Dennis Limestone.
The Drum Limestone is comprised of two members which are, in ascending order, the Cement City Limestone and the Corbin City Limestone. In Neosho County differentiation of the members is difficult as much of the Drum has been removed by pre-Chanute erosion.
In T 28 S, R 18 E the Drum is a light-brown, thin-bedded, fossiliferous limestone that weathers dark brown. Thickness of the unit in this area is about 3 feet. Large crinoid columnals and fenestrate bryozoan fragments are abundant and brachiopods such as Dielasma and Hustedia are common. Sayre (1930, p. 1-129) has described the fauna of the Drum Limestone.
Farther to the southwest, there is a facies change in the Drum. The light-brown, thin-bedded limestone present in T 28 S, R 18 E apparently grades laterally into a medium-gray to yellow-gray, very thick-bedded, finely crystalline, sparsely fossiliferous limestone. The formation ranges in thickness from about 4 feet in T 30 S, R 17 E to 10 feet in T 29 S, R 19 E.
Two sandstone members and an intervening shale member comprise the Chanute Shale in Neosho County. The members are. in ascending order, the Noxie Sandstone, an unnamed shale member, and the Cottage Grove Sandstone.
Noxie Sandstone Member
Thin-bedded to medium-bedded, fine-grained to very fine-grained, quartzose sandstone is characteristic of the Noxie Sandstone Member in Neosho County. Individual sand grains are well rounded to subangular. Silt, silica, and iron oxide are the common cementing materials in this Member. Calcium carbonate cement is rare and is abundant only locally. The thickness of the Noxie ranges from less than 1 foot in the central part of T 27 S, R 19 E to about 30 feet in the southeastern part of T 27 S, R 18 E. Elsewhere along the outcrop, the Noxie has an average thickness of about 6 feet.
In T 27 S, R 18 E the Noxie Sandstone lies unconformably upon the Stark Shale Member of the Dennis Limestone. Drillers' logs of wells drilled southwest and west of Chanute indicate that in the subsurface the Chanute ranges in thickness from about 30 feet to as much as 110 feet. In this area the Noxie appears to have been deposited in a channel about 4 miles wide with a northeast-southwest orientation through the northwestern corner of the county (Fig 4).
Figure 4--Generalized map of the northwest quarter of Neosho County Kansas, showing the approximate location of the ancient channel in which the Noxie Sandstone Member of the Chanute Shale was deposited.
Unnamed shale member
The upper portion of the Noxie Sandstone Member grades into an unnamed shale member. Locally, in the subsurface southwest of Chanute, this unnamed member consists of as much as 7 feet of light grayish-green clay shale which is slightly silty in the upper 2 feet. Drillers' logs show that the Thayer coal commonly lies at the top of this shale and ranges in thickness from 0.4 foot to 2 feet. At outcrops of the Thayer coal the underlying shale is generally less than a foot thick and in some locations a few inches of underclay is seen beneath the coal. This clay shale is not a continuous bed in western Neosho County, and, where it is absent, differentiation of the Noxie and Cottage Grove sandstone members is limited to localities where the Thayer coal is present.
Cottage Grove Sandstone Member
The lithology of the Cottage Grove Sandstone Member is nearly indistinguishable from that of the Noxie Member. However, the Cottage Grove is very thick-bedded in contrast to the generally thin-bedded or laminated Noxie. The massive character of the Cottage Grove Sandstone is well seen in the spillway of Santa Fe Lake at the south edge of Chanute. The weathered surfaces of both the Cottage Grove Sandstone and the Noxie Sandstone are yellowish-orange to deep brownish-red. When unweathered the sandstones of the Chanute Shale are very light gray. This color is the criterion for the well driller's term "white water-sand" commonly applied to the Cottage Grove and Noxie members.
Three members comprise the Iola Limestone in Neosho County. The members are, in ascending order: the Paola Limestone, the Muncie Creek Shale, and the Raytown Limestone. The formation ranges in thickness from about 8 feet near the Wilson County line west of Thayer to about 38 feet in the Ash Grove Cement Company quarry northwest of Chanute.
Paola Limestone Member
Light tannish-gray, finely crystalline, yellowish-brown-weathering limestone is characteristic of the Paola in Neosho County. Small crinoid columnals and brachiopod fragments are common near the base. White, ellipsoidal, phosphatic concretions about 1 inch in their longest dimension occur on the weathered upper surface of the limestone in the west-central and southwestern part of the county. In T 28 S and T 29 S, where the Iola was apparently deposited around erosional remnants of the Chanute Shale, the Paola is slightly sandy. The Member has an average thickness of 2 feet, but in some localities in the southern part of the outcrop the Paola is represented by only a few inches of flaggy, finely crystalline, crinoidal limestone.
Muncie Creek Shale Member
The Muncie Creek Shale Member is dominantly a clay shale that ranges in thickness from about 3 feet in the northern part of T 29 S near the Wilson County line to 5 feet in the western part of T 27 S, R 18 E. In the vicinity of Chanute the Member consists of about 3 feet of light-gray, calcareous clay underlain by approximately 2 feet of black, fissile, carbonaceous shale that contains sparsely distributed, ellipsoidal, phosphatic concretions. Farther to the south along the outcrop the black shale is missing and the Muncie Creek is represented by 2 to 3 feet of gray clay shale.
Raytown Limestone Member
In T 27 S, R 18 E the Raytown Limestone Member consists of about 35 feet of massive-bedded, light-gray, tan-weathering, finely crystalline limestone. Dark-brown, coarsely crystalline veinlets of calcite are seen throughout the Member. Although the Raytown generally is very thick-bedded, bedding planes about 8 inches apart may be seen where the limestone has been exposed to weathering. Southward the Raytown decreases uniformly in thickness so that in the northeastern part of T 29 S, R 17 E., the thickness is about 8 feet. In this area the Raytown is a single massive bed which lacks the bedding planes seen on weathered outcrops farther to the north.
Missourian Stage--Kansas City Group (Zarah Subgroup)
Lane Shale and Bonner Springs Shale
The Lane Shale and the Bonner Springs Shale are considered as a single unit in Neosho County because they are indistinguishable without the intervening Wyandotte Limestone. The sequence is conformably overlain by the Plattsburg Limestone and rests conformably on the Iola Limestone. Total thickness of the Lane and Bonner Springs shales is about 60 feet.
The lower part of the Lane/Bonner Springs is dominantly a blocky, gray to light-gray clay shale. In T 27 S. R 18 E a dark-gray to black shale about 8 feet thick is found in a position 10 feet above the top of the underlying Iola Limestone. Locally, in the northwestern part of the county, a sandy, yellowish-gray shale about 1 foot thick is found immediately overlying the Iola.
The Wyandotte Limestone, a formation that normally lies above the Lane Shale and below the Bonner Springs Shale, is not identifiable in Neosho County. However, a zone of tabular, argillaceous limestone concretions approximately 1 foot thick found above the lower shale unit and about 20 feet below the base of the Plattsburg may represent the normal stratigraphic horizon of the Wyandotte Limestone.
Above the limestone nodules, the shale is yellowish-brown in color and is unfossiliferous except for a 1-foot zone just beneath the Plattsburg where brachiopod and crinoid fragments are common.
Missourian Stage--Lansing Group
The Plattsburg Limestone is the youngest limestone unit in Neosho County. The area of outcrop of the Plattsburg is not extensive, being limited to about 4 square miles in T 27 S, R 17 E, and T 28 S, R 17 E (see Pl. 1).
The three members of the formation, in ascending order, are: the Merriam Limestone, the Hickory Creek Shale, and the Spring Hill Limestone. The thickness of the formation is about 25 feet in the extreme northwest corner of the county and is as much as 50 feet in T 28 S, R 17 E near the Wilson county line.
Merriam Limestone Member
A very finely crystalline, gray to dark-gray bed of fossiliferous limestone that has an average thickness of about 1.5 feet represents the Merriam Limestone Member in Neosho County. The bed weathers to a light grayish-tan color. Marine fossils such as brachiopods, fragments of horn corals, sponges, and crinoid columnals are sparsely distributed throughout the Member.
Vertical joints about 4 feet apart cause the Merriam to appear as discrete blocks at the outcrop. These joints are part of a system, of which one set trends about N 45° W, and the other, which is more obvious on air photographs, trends about N 40° E.
Hickory Creek Shale Member
The middle member of the Plattsburg Limestone is not well exposed in much of its outcrop area. The best exposure of the Hickory Creek Shale Member is southwest of Chanute in a quarry in the SW sec. 25, T 27 S, R 17 E, where it is 3.5 feet thick and consists predominantly of calcareous shale. The shale is light gray but weathers to a light greenish-gray. Very thin laminae of limestone are interbedded with the shale in the lower 2 feet, above which is found a 0.6-foot bed of medium-gray unfossiliferous limestone. In some parts of the quarry a gray shale layer about 1 inch thick is found in the middle of the thin limestone. The upper 1 foot of shale contains more interbedded limestone laminae than does the lower part. In this zone are a few crinoid columnals and fenestrate bryozoan fragments.
Although the Hickory Creek is not well seen in other outcrops of the Plattsburg, especially where the overlying Spring Hill Limestone Member has been removed by erosion, a weathered zone of gray, calcareous material above the Merriam probably represents the Member.
Spring Hill Limestone Member
The upper member of the Plattsburg caps several prominent escarpments along the Wilson county line. The thickness of the Member is about 3 feet where it caps Plattsburg erosional outliers in T 27 S, R 17 E to 20 feet in T 28 S, R 17 E. The 3 feet of Spring Hill probably does not represent the original thickness of the Member in T 27 S, R 17 E. In some localities, the Spring Hill is missing entirely and the Plattsburg escarpments are supported by the Merriam Limestone Member.
The lower portion of the Spring Hill is generally finely crystalline, light bluish-gray to medium-gray, thin-bedded limestone that weathers to a light tan. Yellow clay shale partings are found between the beds in nearly all outcrops. Enteletes and Composita are common in the limestone, and Heterocoelia beedei occurs in the lower part of the Member.
About 8 feet of very thick-bedded limestone is found at the top of the Plattsburg in T 28 S, R 17 E. The lithology is similar to the lower, thin-bedded portion of the Member, except for cross-bedded oolites that are found some places in the upper 2 to 3 feet.
Only weathered remnants of the Vilas Shale Are found in Neosho County. A few feet of weathered light-gray shale is found on the Plattsburg escarpment in T 28 S, R 17 E. In the NW sec. 2, T 27 S, R 17 E, a thin veneer of weathered gray shale is seen overlying the Spring Hill Limestone Member of the Plattsburg Limestone. Generally, in western Neosho County, the Vilas has been weathered, and all that remains on the Plattsburg escarpment are residual clay deposits which no longer retain the characteristics of the formation.
Pre-Kansas deposits of angular to subangular, light-brown chert gravel in a matrix of dark reddish-brown silt and clay are found at several sites in the northern half of Neosho County (Pl. 1). These gravel deposits rest on bedrock surfaces which are 100 to 120 feet above the level of the present flood plain, and 70 to 90 feet above the top of terrace deposits of Kansan age. The thickness of the deposits ranges from a few inches to as much as 12 feet. The chert fragments range in diameter from about 0.5 inch to as much as 2 inches, and comprise about 75 percent of the deposits. While the age of these deposits is unknown, they are as old as Nebraskan and may be as old as Pliocene. It is probable that other deposits of the pre-Kansan gravels occur that are too small or inconspicuous to be seen in the field and, thus, are not mapped.
Material thought to be of Kansan age has been found in only one locality (SW NW sec. 21, T 29 S, R 21 E) in Neosho County (Pl. 1). A deposit of angular to subangular chert pebbles ranging from 1 to 2 inches in diameter in a red clay matrix lies on a bedrock surface about 30 feet above the present flood plain. The thickness of the deposit is about 6 feet, and the areal extent is only a few hundred square yards. Farther north, relatively flat surfaces developed on bedrock immediately adjacent to the Neosho River valley may represent the bedrock floor of a valley cut by the Neosho River during the Kansan glacial Epoch. No deposits have been found on these surfaces which can be identified as Kansan in age.
The most conspicuous geomorphic feature in the Neosho River valley, exclusive of the present flood plain, is the Illinoisan terrace escarpment. Although the terrace has as much as 15 feet of local relief above the flood plain, it is a discontinuous feature and may be differentiated only in a few areas in the valley (Pl. 1). The pronounced escarpment of the terrace is well seen in section C-C' in Figure 5.
The deposits are predominantly silt and clay-sized material in the upper portion with some fine to coarse sand at the base. In some areas, small amounts of the fine chert pebbles are found lying on bedrock at the base of the deposits. Average thickness of the terrace deposits is about 25 feet. Logs of test holes drilled in the Neosho River valley in Neosho County and Labette County may be found at the end of this report.
Figure 5--Geologic cross sections of Quaternary deposits in the Neosho River valley, Neosho and Labette counties, Kansas.
Wisconsinan and Recent Stages
Deposits of Wisconsinan and Recent ages comprise the flood plains of the Neosho River valley and its tributaries. Deposits of Wisconsinan age are similar in lithology to the deposits of Illinoisan age. Silt, fine to coarse sand, and very coarse chert pebbles were found in test holes drilled in this material. Generally, the chert pebbles are confined to a 3-foot zone at the base of the deposits. The thickness of the Wisconsinan deposits ranges from 18 feet to 40 feet and averages about 25 feet. These deposits are confined to the Neosho River valley and have an average width of 1.5 miles (Pl. 1). The maximum width of the flood plain is 4 miles in the southeast corner of the county.
In general, material of Recent age is confined to the active channel of the streams. The deposits consist primarily of silt, clay, fine sand, and chert and limestone pebbles. Near the headwaters of some of the smaller streams, pebbles and cobble-sized fragments of shale occur as bar accumulations in the channel. Thickness of the Recent deposits ranges from a few inches to as much as 10 feet.
A detailed treatment of the structural geology of Neosho County is not within the scope of this report. However, certain gross aspects of the structural setting of the area are evident in the outcropping and near-surface rocks.
The Prairie Plains Monocline is the dominant regional structure that affects the rocks in Neosho County and eastern Kansas. This structure, which is thought to be post-Permian in age, imparts a regional dip to the rocks of about 20 feet per mile to the northwest. Locally, the dip of the strata increases to about 40 feet per mile; in some areas, the rocks are essentially horizontal. This structure is related to the quality of the ground water in consolidated rock aquifers in the county, i.e., the concentration of dissolved solids in water from a given aquifer increases down-dip from the outcrop. The regional structure controls the occurrence of ground water only to the extent that the depth of burial of a given aquifer increases down-dip, and as a result the permeability of the aquifer and the quantity of water available to wells decreases. The apparent domal features southwest of Earlton in T 28 S and T 29 S, R 17 E (Pl. 1) are not structural features, but are sedimentary phenomena which are explained in the section Stratigraphy of Outcropping Rocks.
Kansas Geological Survey, Geology
Placed on web April 17, 2009; originally published December 1966.
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