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Phillips County Geology

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Stratigraphic sections

Because in the past Phillips County has been the focus of a great deal of geologic inquiry, especially of the Pleistocene, measured sections previously reported by Hibbard et al. (1944), Byrne et al. (1948), Frye and A. R. Leonard (1949), Frye and A. B. Leonard (1954), and Frye et al. (1956) have been included, with a few exceptions. Information in brackets is from this study's interpretation of the sections. All previously reported sections were revisited, and some were found to be no longer viable, particularly streambank exposures of alluvium. Also, measured sections from this study have been included.

Section measured in a cutbank along Bow Creek in NW NW sec. 35, T. 5 S., R. 17 W. (Byrne et al., 1948).
Carlile Shale  
Codell Sandstone Member  
3. Sandstone, fine-grained, loosely cemented, rust; limonite-stained 0.2
Blue Hill Shale Member  
2. Shale, noncalcareous, laminated, blue-gray; heavily stained with limonite in upper part 3.5
1. Shale, very thin bedded, clayey and noncalcareous; thin lenses of selenite interbedded; dark-gray to black with some yellow limonite-stained zones 30.0
Base covered  
Total section measured 33.7 ft

Section measured in a cutbank along Bow Creek in NW NW sec. 35, T. 5 S., R. 17 W., immediately above the measured section of the Carlile Shale; top is eroded, but otherwise the section is typical of the stratigraphic unit as it crops out in this area (Byrne et al., 1948).
Niobrara Chalk  
Fort Hays Limestone Member  
Top eroded  
11. Limestone, chalky, cream, weathering to buff-gray; limonite-stained and with pipelike concretions of limonite; upper part shattered; Ostrea 2.5
10. Limestone, chalky; cream, weathering to buff-gray; pipelike concretions of limonite; Inoceramus and Ostrea 2.5
9. Shale, buff-gray; limonite nodules; abundant organic material 0.3
8. Limestone, chalky, light-gray, weathers buff; Inoceramus and Ostrea 1.0
7. Limestone, chalky, white to cream, massive 2.0
6. Shale, gray, very thin bedded; Inoceramus 0.2
5. Limestone, chalky, cream, massive, limonite-stained; Inoceramus and Ostrea 3.7
4. Shale, chalky 0.2
3. Limestone, chalky, cream, massive, limonite-stained; Inoceramus and Ostrea 2.3
2. Shale, chalky 0.1
1. Limestone, chalky, cream, massive, limonite-stained; Inoceramus and Ostrea; basal 0.8 ft somewhat sandy and heavily stained with limonite 3.5
Total section measured 18.3 ft

Section measured on the north face of a quarry in SE SW sec. 31, T. 5 S., R. 17 W. (this study).
Niobrara Chalk  
Smoky Hill Chalk Member  
10. Chalk, medium-bedded (to 0.2 ft), very pale brown to yellow, weathered; indistinct boundary with Fort Hays Limestone Member 5.3
Fort Hays Limestone Member  
9. Limestone, massive, chalky, very pale brown with basal 0.9 ft light-gray; Ostrea; limonite staining 2.4
8. Shale, fine-bedded, light-gray to gray; Inoceramus fragments 0.3
7. Limestone, massive, chalky, very light gray; faint limonite stains 4.5
6. Shale, fine-bedded, light-gray to gray; organic concentrations 0.4
5. Limestone, massive, chalky, light-gray with basal 0.5 ft very pale brown; scattered small fossil fragments 3.6
4. Shale, fine-bedded, light-gray to gray; small limonite concentrations 0.2
3. Limestone, massive, chalky, very pale brown with basal 1.8 ft light-gray; small limonite concretions; Inoceramus 4.3
2. Shale, fine-bedded, gray 0.3
1. Limestone, massive, chalky, very pale brown; faint limonite streaks 2.5
Total section measured 23.8 ft

Section measured in a cutbank in SE SE sec. 35, T. 2 S., R. 17 W. (Byrne et al., 1948).
Niobrara Chalk  
Smoky Hill Chalk Member  
Top eroded  
12. Chalk, massive, streaked white and tan; fossil fragments 4.5
11. Chalk, flaky, pinkish-tan; fossil fragments 0.2
10. Chalk, massive, tan, weathering to buff; Ostrea 0.7
9. Shale, chalky, thin-bedded, alternating pink and tan beds 4.0
8. Chalk, blocky, pink and buff 1.5
7. Shale, chalky, thin-bedded, pink 3.7
6. Shale, bentonitic, rust-brown 0.1
5. Shale, chalky, platy, light-gray and pink 1.5
4. Chalk, blocky, light-gray 1.8
3. Shale, chalky, thin-bedded, gray 1.6
2. Chalk, shaly, blocky, tan, weathering to light-gray 0.4
1. Chalk, shaly, blocky, light-gray, weathering to blue-gray 5.0
Total section measured 25.0 ft

Section measured along creek bank in SW sec. 6, T. 1 S., R. 19 W. (Frye and A. R. Leonard, 1949).
Pierre Shale  
Sharon Springs Shale Member  
18. Shale, thin-bedded, dark-gray; fine gypsum crystals and limonite along bedding planes 2.0
17. Shale, fissile, dark-gray, noncalcareous; ochre on bedding planes 1.3
16. Chalky paper shale, yellow-brown 0.05
15. Shale, fissile, dark-gray; noncalcareous; contains bands of ochre, gypsum crystals, and limonite 3.5
14. Bentonite, impure, with limonite and calcareous shale 0.1
13. Shale, fissile, dark-gray; noncalcareous; bands of ochre, gypsum crystals, and limonite on bedding planes 5.0
12. Bentonite with gypsum and limonite 0.05
Niobrara Chalk  
Smoky Hill Chalk Member  
11. Chalky shale, thin-bedded, gray, weathers to yellow-tan 1.5
10. Bentonite, yellow-tan 0.3
9. Chalk, dark-gray, massive 0.7
8. Bentonite, impure, yellow-tan 0.05
7. Chalk, thin-bedded, dark -gray, breaks with a conchoidal fracture on exposed surfaces, weathers to light-orange 1.5
6. Bentonite, yellow-tan 0.2
5. Chalk, massive, dark-gray, weathers to light-orange 0.9
4. Bentonite 0.05
3. Chalk, thin-bedded, dark-gray 0.8
2. Bentonite 0.01
1. Chalk, thick-bedded, dark-gray; from low water level in Prairie Dog Creek 2.0
Total section measured (approx.) 20 ft

Section measured in a cutbank in SE NE sec. 35, T. 1 S., R. 20 W. (Byrne et al., 1948).
Pierre Shale  
Sharon Springs Shale Member  
Top eroded  
10. Shale, clay, blocky, light-green; small limonite concretions 3.0
9. Shale, clay, thin-bedded, rust with thin gray zones 0.7
8. Shale, clay, thin-bedded, blue-gray; limonite-stained 0.8
7. Shale, bentonitic, blocky, rust 0.4
6. Shale, clay, blocky, blue-gray; thin local lenses of limestone interbedded 0.4
5. Shale, bentonitic, thin-bedded, rust 0.3
4. Shale, clay, thin-bedded, blue-black 1.4
3. Shale, thin-bedded, blue-gray; abundant small selenite crystals; limonite-stained 0.4
2. Shale, somewhat bentonitic, thin-bedded, rusty-blue; abundant selenite crystals 0.3
1. Shale, thin-bedded, blue-black with streaks of limonite stain; abundant selenite crystals 6.0
Base covered  
Total section measured 13.7 ft

Section measured along valley and tributary gullies in NW SW sec. 31, T. 1 S., R. 19 W. (Frye and A. R. Leonard, 1949).
Tertiary [Miocene]  
Ogallala Formation  
Ash Hollow member  
11. Sand and silt, cemented with calcium carbonate 1.5
10. Clay, silt, and fine sand, partly cemented, light gray-green; contains nodules and stringers of calcium carbonate 12.0
9. Sand, loosely cemented with calcium carbonate, gray; contains fossil seeds of Biorbia fossilia (Berry) 3.0
8. Clay, silt, fine sand, and calcium carbonate, gray 2.0
7. Sand, medium to fine, cemented in upper part, greenish-gray; contains fragments of fossil vertebrates 4.0
6. Sand, coarse to fine, and some silt; massive to irregular bedding, weathers to irregular, pitted surface, greenish-gray; fossil seeds of Krynitzkia coroniformis Elias, Biorbia minor Elias, Prolighospermum corrugatus Elias, Panicum elegans mut. nebraskanse Elias, Stipidium intermedian Elias, and Stipidium cf. grande Elias occur in this interval and in the upper part of bed 5 6.0
5. Sand, coarse to fine, and some silt, massive to irregularly bedded; cemented more firmly toward top 4.0
4. Partly covered. Sand, fine to medium, loose, pink-tan; contains concretions and nodules of calcium carbonate 15.0
3. Partly covered. Sand, fine to medium, loose, pink-tan; contains concretions and nodules of calcium carbonate 12.9
2. Sand and silt, massive to irregularly bedded, loosely to unevenly cemented with calcium carbonate, pale pinkish-tan to gray 14.8
1. Clay, silt, and sand with some calcium carbonate, gray to green-gray; from bottom of creek 1.8
Total section measured 77.0 ft

Measured section of Ogallala Formation in SW sec. 13, T. 5 S., R. 19 W. (A. R. Leonard, 1952).
Quaternary (Pleistocene)  
[Peoria loess]  
12. Silt and sand, tan 8.0
Tertiary [Miocene]  
Ogallala Formation  
11. Quartzite, fine-grained, dense, green 1.5
10. Sand, massive, green and red; contains fragmentary mastodon tooth 5.0
9. Quartzite, fine-grained, fairly well cemented, green 1.0
8. Sand and silt, massive, green, spotted and streaked with calcium carbonate 3.0
7. Silt and sand, massive, partly silicified, hard, light-gray 1.5
6. Sand and silt, massive, green, spotted and streaked with calcium carbonate; weathers to a deeply etched surface of vertical columns and horizontal sheets 1.0
5. Sand, fine, and silt, green; speckled with calcium carbonate 2.5
4. Quartzite, fine-grained, lenticular, light-green 1.5
3. Silt and fine sand, partly covered, light greenish-gray, weathers to ash-gray; contains few nodules of calcium carbonate 2.5
2. Sand, fine and silt, indistinct bedding, very light greenish-gray , weathers to platy and nodular surface; loosely cemented throughout with calcium carbonate; forms indistinct bench along nearby canyon side 4.5
1. Silt, sandy, calcareous; contains calcium carbonate in irregular nodules and stringers; upper part more clayey, darker gray, contains less carbonate 6.0
Total section measured 38.0 ft

Section measured in NW NE sec. 30, T. 1 S., R. 19 W. (Frye et al., 1956).
Tertiary [Miocene]  
Ogallala Formation  
Ash Hollow member  
9. Sand, fine to coarse, a few pebbles, irregularly cemented throughout with calcium carbonate 7.0
8. Silt, fine sand, and clay, uncemented, mottled gray-brown and green 6.0
7. Clay, silty, some fine sand, tan to gray-greenish-tan 5.0
6. Silt and fine sand, some mica flakes and ash shards, laminated, tan, mottled with greenish-gray; contains Biorbia fossilia, Celtis willistoni, Krynitzkia coroniformis, Stipidium elongatum, and S. grande 1.5
5. Silt, bentonitic clay, and fine sand, interbedded, tan to greenish-tan 8.0
4. Marl and volcanic ash containing diatoms and abundant molds of snails (Vertigo ovata, Pupoides albilabris, Physa anatina, Helisoma antrosum, H. valens, Pseudosuccinea columella); whitish to cream 2.5
3. Volcanic ash, Rawlins bed, clean and fresh, uncemented, blue-gray 1.0
2. Sand, some zones of silt and bentonitic day, locally loosely cemented with calcium carbonate, greenish-gray 3.0
1. Covered interval from bridge (culvert) floor 4.0
Total section measured 38.0 ft

Section measured in the west face of a sand and gravel pit located in the eastern half of NE sec. 26, T. 2 S., R. 20 W. (this study).
Quaternary (Pleistocene)  
Peoria loess  
5. Silt, fine to medium, noncalcareous, very dark gray, humus-rich, bioturbated; surface soil developed throughout 2.3
Tertiary [Miocene]  
Ogallala Formation  
upper Ash Hollow member (?)  
4. Sand, fine, soft, calcareous, modular structure, very light gray; degree of cementation increases upward 7.5
3. Coarse sand and fine gravel, calcareous, pinkish-white; channel fill; forms a vertical face due to carbonate cementation 2.4
2. Coarse sand and medium to coarse gravel, calcareous, very pale brown, carbonate nodules 10.7
1. Coarse sand and medium gravel, with clasts to 2.8-in. diameter, calcareous, soft, poorly cemented, thinly bedded, olive-green; Rocky Mountain lithology apparent; clay balls up to 7-in. diameter 12.2
Total section measured 35.1 ft

Kirwin Dam section, measured in cutoff trench excavation in the high terrace of North Fork Solomon River valley, SW sec. 28 and SE sec. 29, T. 4 S., R. 16 W.; November 1, 1953 (Frye and A. B. Leonard, 1954).
Quaternary (Pleistocene)  
Peoria loess  
9. Silt, massive, well-sorted, calcareous (except 0.5 ft), light-tan; contains transition zone in base above contact on Sangamon soil; lower part oxidized to pale pinkish-tan; terrestrial gastropods in middle part 10.0
Crete-Loveland Formation  
8. Silt, sand, and clay, massive to thinly bedded and crossbedded, light-brown to tan; coarser in lower part; contains lentils of sand and chalk gravel and locally coarse crossbedded gravel at base; middle and upper parts relatively poorly sorted with thin dispersed sand and gravel lentils. Top 2.5 ft is Sangamon soil; upper 0.5 ft (A horizon) is friable brown silt loam; 1 ft (B horizon) light-brown silty clay loam with well-developed prismatic structure; 1 ft (upper C horizon) massive light-brown sandy silt with sparse lime mottling along joints and dispersed lime nodules. Five weakly developed soils occur below the Sangamon soil; upper four soils pale pinkish-brown, less than 1 ft thick, with weak textural contrast and structures; lowermost soil, 5 ft above base, nearly 2 ft thick with silty clay loam B horizon. Terrestrial gastropods occur sparsely throughout lower half 32.0
Sappa Formation  
7. Silt and sand; lower 1 ft massive tan sandy silt containing terrestrial and freshwater gastropods. Yarmouth soil (Frye and A. B. Leonard, 1954, pl. 2) profile in upper 3.5 ft; upper 0.5 ft (A horizon) friable gray-brown massive to granular loam; 1.5 ft (B horizon) dark gray-brown sandy clay loam with strongly developed prismatic structure; 1.5 ft (C horizon) massive silt and sand, dark gray-brown at top to tan, with lime mottling throughout but concentrated in upper part; lime nodules rare 4.5
Grand Island Formation (66.5 ft)  
6. Sand and gravel, lenticular, interbedded fine and coarse with a few silty zones; contains pebbles and cobbles (up to 1 ft in diameter) of Cretaceous chalk and sand and fine gravels predominantly of quartz, feldspar, and granitic grains similar to those of the Ogallala Formation farther west; discontinuous zone of yellow-brown limonitic staining at top; at southeast end of trench is a lentil of [presumed] Pearlette volcanic ash, 2-3 ft thick, near top of this interval above high Cretaceous bedrock  
5. Silt and fine sand, well-sorted, thin-bedded to laminated, locally intricately crossbedded in zones 1-3 in. thick, tan to gray-tan; laterally replaced by sand and gravel 4.5
4. Silt, sand, and clay, massive in a persistent zone of lentils; black, dark-gray, and tan; dark organic coloring distributed lenticularly through zone; calcareous throughout; locally sand and gravel occur in this zone; shells of terrestrial gastropods throughout 5.0
3. Sand and gravel, crossbedded, lenticular, gravels predominantly of Cretaceous chalk; similar in lithology to unit 6 above 5.0
2. Silt, sand, and clay, massive, black to gray-brown, calcareous, similar in lithology to unit 4; occurs as discontinuous lentils in sand and gravel; contains shells of terrestrial gastropods 2.0
1. Sand and gravel, cross bedded, lenticular; contains pebbles and cobbles of Cretaceous chalk; coarser textured than unit 3 above and locally gradational with it 8.0
Total Pleistocene section measured 113 ft

Measured section of Pleistocene deposits in SW SW sec. 24, T. 4 S., R. 19 W. (A. R. Leonard, 1952).
Quaternary [Holocene]  
Bignell Loess  
4. Silt, light-gray; fills a shallow depression and thins to north and south (max.) 5.0
Quaternary (Pleistocene)  
Peoria loess  
3. Silt, fossiliferous, light yellow-buff; contains black clayey, sandy soil zone (Brady fossil soil) at top and slight caliche accumulation 2 ft below top (avg.) 11.0
Loveland Loess  
2. Silt, calcareous, reddish-buff; contains much chalk material in lower part; upper 4 ft is fossil soil zone, clayey, dark chocolate-buff 8.0
Niobrara Chalk  
Smoky Hill Chalk Member  
1. Shale, chalky, soft, yellow-buff, deeply weathered  
Total Pleistocene section measured 24.0 ft

Section measured in NW sec. 9, T. 2 S., R. 16 W. (Hibbard et al., 1944).
Quaternary (Pleistocene)  
[Peoria loess]  
4. Silt, massive, gray, pipelike concretions of calcium carbonate throughout; gray-tan in part 45.0
[Gilman Canyon Formation]  
3. Soil zone, massive, dark gray-brown to black; weathers to a checked surface 4.0
[Loveland-Crete Formation (?)]  
2. Silt and sand in basal part consisting of grains and a few pebbles of chalk and chalky shale and quartz; becomes finer and more even textured upward; light red-brown at top and yellow-gray at base; massive; snails occur 10 in. above base 5.5
Niobrara Chalk  
1. Chalk and chalky shale  
Total Pleistocene section measured 54.5 ft

Section measured in SE sec. 5, T. 2 S., R. 17 W. (Hibbard et al., 1944).
Quaternary (Pleistocene)  
[Peoria loess]  
5. Silt, massive, gray in lower part grading into light buff-tan in upper part, porous, tubular concretions rare except in a few localities; snails occur in zones 6 ft and 10 ft above base 30.0
[Gilman Canyon Formation]  
4. Soil zone, massive, gray-brown to very dark gray, weathers to dark purple 4.5
[Loveland-Crete Formation]  
3. Silt, red, massive, a few quartz sand grains throughout 3.5
2. Silt, sand, and gravel, mostly of chalk but some quartz and granite, contains a few large pebbles of chalk, light-gray; a few snails 4.5
1. Sand, silt, and gravel, cemented with calcium carbonate; gravel composed mostly of Cretaceous rock fragments; numerous irregular hollow concretions 9.0
Total Pleistocene section measured 51.5 ft

Section measured in a trench excavated for refuse at the Phillips County sanitary landfill, located in the southern half of SW SE sec. 34., T. 3 S., R. 18 W. (this study).
Quaternary (Pleistocene)  
5. Silt, medium to coarse, wind-deposited, massive, calcareous, pale-brown (10YR 6/3); modern surface soil truncated to thickness of 2.3 ft; flecks of carbonate in lower 7.6 ft; terrestrial gastropods in upper third indicate Leonard's upper zone (e.g., Columella alticola and Discus shimeki) 11.6
4. Silt, medium, wind-deposited, noncalcareous, leached, grades upward from dark-brown (10YR 3/3) to grayish-brown (10YR 5/2); Leonard's basal zone; attenuated A horizon of Gilman Canyon Formation below 3.1
Gilman Canyon Formation  
3. Silt, medium to fine, wind-deposited, humus-rich, leached, bioturbated; very dusky red (10R 2.5/2) to very dark brown (10YR 2/2); fragments of small mammal bone; increase in clay at base; fine carbonate root traces; lower solum (Btkb) developed into underlying silt 3.5
Loveland Loess  
2. Silt, coarse to medium, wind-deposited, massive, compact, calcareous, yellow (10YR 7/8); upper 1.6 ft clayey, very compact, with carbonate nodules and root traces; truncated Sangamon soil 7.6
Crete Formation  
1. Sand, very fine to fine grained, few small granitic pebbles, calcareous, soft, yellow (10YR 7/6) to brownish-yellow (10YR 6/6) 4.0
Total section measured 29.8 ft


Appreciation is expressed to the many residents of Phillips County who provided access to their land and information concerning local geology, soils, stream systems, and historical events. D. W. May of the University of Northern Iowa and graduate students in the Department of Geography at the University of Kansas contributed many useful field observations. Two anonymous reviewers kindly provided constructive comments.

Mapping the geology of Phillips County would have proven a much more difficult task and would have taken far longer had it not been for the assistance and dedication of Alan Arbogast, co-author of the county geologic map. The Dane Hansen Foundation of Logan, Kansas, generously contributed funds for the project.

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Kansas Geological Survey, Geology
Placed on web Feb. 9, 2013; originally published 1993.
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