The appended descriptions are for sections that comprise the composite section of the Smoky Hill Member in the type area. Descriptive details are based largely on field notes, supplemented by species identifications made in the laboratory. All sections were measured by steel tape, stadia rod, and hand-level techniques. Colors (wetted rock) are based on the well-known Rock Color Chart (Goddard and others, 1948), and color-code numbers are used only to distinguish between color chips that have the same name or for colors that are not represented by a color chip. Ferruginous or ferruginous-gypsiferous seams are probably very thin, weathered bentonite seams. The speckled appearance accorded most chalk units is owing to presence of flattened, coccolith-rich fecal pellets. Unit numbers are the same as those shown on Plate 1. The sections are described in overlapping order, from the top of the member downward. Correlation of equivalent beds is shown on Plate 1.
| LOCALITY 21--Section exposed along cut banks of intermittent tributary to Ladder Creek, NE Sec. 20 and NW Sec. 21, T. 15 S., R. 32 W., Logan County, Kansas. |
Thickness |
| m |
cm |
| PIERRE SHALE |
| 63. | Bentonite, nearly white, with medium bluish gray band near base; very brittle, very silty, has bitter taste, makes conspicuous streak on gray shale slope; overlain by gray, noncalcareous shale | | 0.5 |
| 62. | Shale, olive black to dark olive gray (5Y3/1), dries medium light gray; noncalcareous, silty, fissile, weathers flaky, stained by iron oxide, some jarosite stains on joints and bedding surfaces; contains abundant small crystals and rosettes of selenite; overall slope color is conspicuously greenish gray | | 32.0 |
| Measured thickness of Pierre Shale | | 32.5 |
| SMOKY HILL CHALK MEMBER |
| 61. | Calcareous shale, olive gray (5Y4/1), dries very light gray to light gray; pronounced color change on slope above top of unit; very calcareous at base, nearly noncalcareous at top; silty, not speckled, weathers flaky | | 20.5 |
| 60. | Bentonite, pale orange (10YR712), silty, stained by iron oxide and jarosite along fractures; made conspicuous by thickness and position close to color change at base of Pierre Shale | | 5.0 |
| 59. | Calcareous shale and noncalcareous shale, alternating; calcareous shale dark olive gray, dries very light gray; noncalcareous shale olive black, dries near olive gray (5Y4/1), weathers thinly flaky | | 73.2 |
| 58. | Bentonite, very pale orange, partly stained dark yellowish orange by limonite, slightly silty, soft, and mushy | | 2.5 |
| 57. | Chalky shale, calcareous shale, and noncalcareous shale, represents initial upward transition to Pierre Shale; basal 9 cm shaly chalk, olive gray (5Y4/1), very tough, moderately speckled, grades upward into dark gray, nearly noncalcareous shale 27.5 cm above base, then grades upward into olive gray calcareous shale; uppermost 3.0 cm are dark gray noncalcareous shale; entire unit weathers soft and flaky, contains finely granular gypsum; least calcareous units contain jarosite; persistent ferruginous-gypsiferous seam lies 40 cm above base | | 76.0 |
| 56. | Bentonite, pale orange (10YR7/2), stained dark yellowish orange by iron oxide, silty, feels waxy | | 2.7 |
| 55. | Chalky shale, dark olive gray (5Y3/1), dries light gray, very silty, moderately speckled, breaks blocky, weathers flaky on slope; more argillaceous and silty than typical Smoky Hill units below; ferruginous-gypsiferous seam, limonitic and jarositic, 0.5 cm thick, lies 27.5 cm above base | | 79.3 |
| 54. | Bentonite, yellowish gray (5Y7/2), mostly stained dark yellowish orange, almost nonsilty, feels waxy | | 1.3 |
| 53. | Chalk, olive gray (5Y4/1), calcareous silty, speckled throughout, weathers soft and crumbly, crinkly structure throughout; contains prominent ferruginous-gypsiferous seam about 1 mm thick that marks a very thin seam of slightly silty, pale grayish orange bentonite. FOSSILS: teleost scales | | 79.3 |
| 52. | Bentonite, mostly stained dark yellowish orange by iron oxide, contains large crystals of selenite, seam. conspicuous because of heavy limonitization that locally expands unit to 6-cm thickness | | 1.0 |
| 51. | Chalk, olive gray (5Y4/1), calcareous silty, speckled throughout, weathers soft and finely flaky, crinkly seams of gypsum abundant. FOSSILS: teleost scales, plesiosaur remains | | 47.3 |
| 50. | Bentonite, medium light gray, very silty, feels very waxy | | 2.8 |
| 49. | Chalk, olive gray (5Y4/1), calcareous silty, speckled throughout, weathers soft and finely flaky, crinkly structure throughout. FOSSILS: teleost scales | | 44.2 |
| 48. | Bentonite, apparently dark olive gray, nearly nonsilty, 2 mm thick; seam heavily mineralized by limonite and jarosite; unit marked by projecting ledges of limonite above and below seam; mineralization causes unit to expand locally to thickness of 7.5 cm | | 1.2 |
| 47. | Chalk, olive gray (5Y4/1), dries medium light to very light gray, calcareous silty, moderately speckled, weathers sof, and finely flaky, crinkly structure throughout. FOSSILS: teleost scales, teleost jawbone, Inoceramus fragments, isolated small ostreid | | 49.0 |
| 46. | Bentonite, light bluish gray, mostly weathered dark yellowish orange, silty, feels waxy, some limonite and gypsum | | 2.8 |
| 45. | Chalk, olive gray (5Y4/1), dries medium light to very light gray, calcareous silty, moderately speckled; upper and lower parts weather soft and flaky, with crinkly structure; central 30 cm more massive, less crinkly, forms minor ledge | | 76.2 |
| 44. | Bentonite, olive gray (5Y4/1), mostly white and much weathered, limonitic and jarositic, approximately 6 mm thick; seam marked by projecting ledges of limonitic chalk at top and base | | 1.3 |
| 43. | Chalk, olive gray (5Y4/1), dries medium light to very light gray, calcareous silty, moderately speckled, weathers minutely flaky, all but basal 3.0 cm with crinkly structure; basal 30 cm slightly more massive and tougher; lowest 20 cm tends to weather very pale orange to grayish orange pink locally; unit contains local small limonite nodules. FOSSILS: Pseudoperna congesta (float), teleost bones and scales | | 67.1 |
| 42. | Bentonite, near yellowish gray (5Y8/1); in part stained dark yellowish orange by limonite, slightly silty, feels waxy | | 4.0 |
| 41. | Chalk, olive gray (5Y4/1), weathers near pale yellowish brown, calcareous silty, moderately to much speckled throughout, relatively soft, mostly weathers to minute flakes; much crinkly structure above basal 9 cm, less crinkled in upper 9 cm; basal 9 cm light-colored, near pale grayish orange (10YR8/4), weathers shaly. FOSSILS: Pseudoperna congesta (float), teleost scales | | 58.0 |
| 40. | Bentonite, medium dark gray, bleaches medium light gray to very light gray, stained dark yellowish orange where weathered, very silty | | 11.5 |
| 39. | Chalk, medium to dark yellowish brown, dries very light to light gray, calcareous silty, speckled throughout, weathers soft and finely flaky, crinkly structure throughout | | 64.0 |
| 38. | Bentonite, weathered, dark yellowish brown, highly limonitic, slightly silty, feels waxy, marked by conspicuous row of small (15 cm X 5 cm) limonite-pyrite nodules; locally contains large selenite crystals | | 0.6 |
| 37. | Chalk, olive gray (5Y4/1), tough; weathers medium yellowish brown, soft; calcareous silty, speckled throughout, not obviously laminated but has good fissility, apparently with crinkly structure throughout, weathers finely flaky, most of unit forms spally, smoothly curved face; upper half with minor, ledge-forming interval; seam of ferruginous matter lies 7.5 cm above base. FOSSILS: teleost bones and scales, Inoceramus balticus, Pseudoperna congesta | | 90.0 |
| 36. | Chalk or chalky limestone, olive gray (5Y4/1) to dark yellowish brown, massive, tough, calcareous silty, speckled, weathered surface roughened by projecting edges of horizontal, wafer-like gypsum bodies; crinkly structure especially prominent in upper half; unit forms vertical, spally face where fresh, pronounced overhanging ledge where weathered; one inoceramid valve partially pyritized. FOSSILS: Inoceramus balticus, sparse inoceramid fragments, teleost bones and scales | | 61.0 |
| 35. | Bentonite and chalk; lower of two bentonite seams is 1.5 cm thick, dark yellowish orange, slightly silty, brittle, feels waxy; upper seam is 0.6 cm thick (less than 0.3 cm where not weathered), olive gray to light olive gray, silty, waxy, consists mostly of selenite crystals; bentonite seams are separated by shaly weathering chalk, olive gray (5Y4/1), speckled, in part weathered dark grayish orange. FOSSILS: in chalk, Inoceramus balticus, teleost scales | | 5.5 |
| 34. | Chalk, olive gray (5Y 4/1), dries light gray, calcareous silty, speckled, crinkly structure throughout, very tough where fresh, forms vertical spally face, weathered very finely flaky | | 24.5 |
| 33. | Chalky limestone, partly weathered, medium yellowish brown (10YR5/2), dries very pale orange; forms steep spally face where fresh, conspicuously ledge-forming where weathered; forms smoothly rounded shoulder on slopes; weathered surface rough textured; horizontal, wafer-like gypsum bodies project from surface in lower 9 cm; limonite-pyrite nodules as much as 21 cm by 2 cm thick occur locally near center of unit; limonitic and jarositic seam, possibly weathered bentonite, lies 2 cm below top and hosts numerous small pyrite and limonite nodules. FOSSILS: Inoceramus balticus, teleost bones and scales | | 35.0 |
| 32. | Chalk, olive gray (5Y4/1) to medium olive gray (5Y5/1), locally weathering to vivid yellowish orange, calcareous silty, more or less speckled throughout; unit comprises alternating thin to medium thicknesses of very tough chalk that forms smoothly rounded ledges and softer, shaly weathering chalk that is filled with crinkly structures that lie parallel to bedding; main tough beds lie (ascending) 0.0 to 3.0 cm, 40 to 55 cm, 58 to 63 cm, and 98 to 110 cm above base; unit contains scattered small limonite nodules. FOSSILS: teleost? skeleton, teleost scales, Pseudoperna congesta attached to inoceramid fragments, coprolite | 1 | 33.0 |
| 31. | Bentonite, medium yellowish brown (10YR512); contains much finely crystalline selenite | | 0.6 |
| 30. | Chalk, olive gray (5Y4/1), dries light gray, speckled throughout, very tough; basal 15 cm forms light-colored shoulder on slope; remainder of unit weathers flaky, forms slope. FOSSILS: Pseudoperna congesta, possibly float from unit 32 | | 20.0 |
| 29. | Bentonite, mostly dark yellowish orange with minor yellowish gray coloration; seam composed mostly of limonitic bentonite, with thin seams of prismatic selenite above and below | | 2.8 |
| 28. | Chalk, all partly weathered to medium olive gray (5Y5/1), light olive gray (5Y5/2), medium yellowish brown (10YR512), and dark yellowish brown; slope dries mostly light gray to very light gray, locally very pale orange; speckled throughout; intervals of softer, flaky weathering rock predominate, alternate with beds of tough, more resistant rock that forms rounded shoulders on slope and forms white bands when viewed from a distance; most prominent resistant layers have upper limits 98 cm and 1.58 m above base of unit. Laterally unit passes into medium light gray to medium gray, less-weathered chalk, which forms vertical spally face. From a distance, unit appears distinctly laminated, unlike most of underlying unit. In a local area of adjacent badlands, unit weathered to vivid yellowish orange color. Thin zone, 7.5 cm thick, comprising soft, crinkly bedded, shaly weathering chalk, marked by thin wafers of gypsum, lies 1.31 m above base of unit. Zone of widely spaced limonitic pyrite nodules lies 85 cm above base of unit. FOSSILS: sparse Inoceramus balticus, Pseudoperna congesta, teleost bones | 2 | 1.5 |
| 27. | Chalk and chalky limestone, medium olive gray in basal part grading to pale yellowish brown or medium yellowish brown (10YR5/2) in upper part; lower part and uppermost 37 cm weather very pale orange, remainder dries light gray; in nearby badlands, entire unit weathers moderate reddish orange; unit forms steep, spally face where little weathered, forms two or three rounded shoulders where weathered. Lowest 76 cm forms overhanging ledge where weathered; uppermost 37 cm is major, light-colored bench former and caps low pinnacles in nearby reddish-colored badlands; part of unit has tendency to weather shaly; contact with unit 28 somewhat arbitrary. All of rock is tough, speckled throughout, and from distance appears thinly stratified, but is not well laminated. Exposed faces exhibit prominent bed-parallel lines, not associated with bentonite, at 76 cm, 1.42 m, 1.62 m, and 1.89 m above base; line at 1.62 m has sparse associated iron oxide. Very thin, small wafers of selenite project conspicuously from weathered face in zone 7.5 cm thick, which lies 33 cm above base of unit. FOSSILS: Inoceramus fragment, Pseudoperna congesta, pectinids, teleost bones and scales, coprolite | 2 | 20.0 |
| 26. | Bentonite, light brown (5YR5/6), as scattered flakes in seam consisting of mostly dark yellowish orange, finely granular gypsum, limonite, and jarosite | | 1.0 |
| 25. | Chalky limestone, all partly weathered, mostly dark yellowish brown to medium yellowish brown (10YR5/2) or grayish orange, relatively hard, punky where moist, speckled throughout; forms smoothly curved, spally surface where least weathered; forms resistant, cavernous, overhanging ledge where most weathered. Spally surfaces are olive gray (5Y4/1) to medium light gray where least weathered. Prominent line, not associated with bentonite, lies 27 cm above base, and forms minute reentrant locally. Very thin wafers of gypsum abundant in first 12 cm above line and also 35 cm below top. Unit forms resistant caprocks in nearby badlands, where unit weathers to conspicuous moderate reddish orange color. FOSSILS: Inoceramus (Platyceramus) platinus?, Pseudoperna congesta, teleost bones and scales | | 94.5 |
| 24. | Bentonite. Seam consists mostly of powdery gypsum, which contains local clayey lenticles. Bentonite represented only by 0.03 cm of waxy chalk at base of unit | | 1.2 |
| 23. | Chalky limestone, olive gray (5Y4/1) to medium dark gray, mostly weathered pale to very pale yellowish brown (10YR7/2), relatively hard, resistant, forms vertical faces to rounded, overhanging ledges that locally display cavernous weathering. Vertical and steep faces weather spally. Unit not obviously burrowed or laminated; some exposed surfaces manifest obscure laminae; rock has moderately developed fissility. Crinkly structure abundant in thin zones 23 cm below top of unit and 40 cm above base. Prominent line, forming reentrant, not associated with bentonite, lies 1.05 m above base. FOSSILS: teleost bones | 1 | 77.0 |
| 22. | Bentonite, olive gray (5Y4/1), as chips in seam consisting mostly of finely granular gypsum | | 1.0 |
| 21. | Chalky limestone, all partly weathered, pale yellowish brown to dark yellowish brown, tough, upper part generally punky, speckled throughout, neither burrowed nor laminated. Unit weathers cavernous locally, forms overhanging ledge locally. FOSSILS: inoceramid fragments, teleost scales | | 24.5 |
| 20. | Bentonite, yellowish gray (5Y7/2), stained dark yellowish orange, silty, with associated finely crystalline selenite and some limonite | | 1.0 |
| 19. | Chalky limestone, light olive gray (5Y5/2), medium olive gray (5Y4/2) on fresh vertical face, top of bed grayish orange with liesegang banding, homogeneous, neither laminated nor obviously burrowed, rather punky, passes laterally into orange-weathering limestone that forms overhanging ledge. FOSSILS: teleost scales | | 41.0 |
| 18. | Bentonite, marked by nearly white seam of powdery gypsum, locally contains small flakes of grayish orange bentonite | | 0.6 |
| 17. | Chalky limestone, light olive gray (5Y512), slightly darker in lower part, weathers pale grayish orange (10YR8/4), liesegang-banded in upper part, neither laminated nor burrowed, speckled throughout, tough to somewhat punky, relatively brittle where weathered. Unit forms vertical face where fresh, overhanging ledge where weathered | | 9.2 |
| 16. | Bentonite, two seams, separated by chalk. Lower bentonite seam 0.6 cm thick, dark yellowish orange, brittle, slightly silty. Upper seam 1.9 cm thick, grayish orange, silty, waxy. Chalk medium olive gray (5Y412), calcareous silty, much speckled, weathers flaky | | 4.3 |
| 15. | Chalky limestone, medium gray, weathers grayish orange to medium yellowish brown (10YR512), tough, speckled throughout, appears faintly laminated on least-weathered faces. Steep faces smoothly curved, sloping faces weather spally. Where weathered, unit forms overhanging ledge. FOSSILS: small teleost bones | | 79.3 |
| 14. | Bentonite, olive gray (5Y412), as waxy clay at top of seam consisting mostly of light-colored, finely crystalline, slightly clayey selenite | | 0.6 |
| 13. | Chalky limestone, medium gray, weathers grayish orange to medium yellowish brown (10YR5/2, tough, somewhat punky on exposed surfaces, speckled throughout, appears indistinctly laminated on fresh surfaces. Unit forms smoothly curved, nearly vertical face where fresh, prominent overhanging ledge where weathered. Prominent line, not associated with bentonite, lies 23.5 cm above base and forms reentrant on overhanging ledge. FOSSILS: teleost bones, scales, and teeth | | 61.0 |
| 12. | Bentonite, two(?) seams, separated by chalk. Lower seam is 0.3 cm thick, consists of vertical crystals of selenite, with no evidence of bentonite; upper seam 0.6 cm thick, grayish orange, bentonite occurs as scattered flakes in medium crystalline granular selenite. Chalk is 1.5 cm thick, dark yellowish brown, dries grayish orange pink, soft | | 2.4 |
| 11. | Chalk, dark olive gray (5Y3/1) to olive gray (5Y4/1), in part weathered very pale yellowish brown (10YR712), relatively hard, brittle, calcareous silty, speckled throughout, faintly laminated, with good fissility. Two prominent lines, without associated bentonite, lie 9.2 and 45.7 cm above base. FOSSILS: inoceramid fragments, ostreid bivalves | | 70.1 |
| 10. | Bentonite, two seams, separated by chalk. Lower bentonite 0.3 cm thick, upper seam 0.9 cm thick. Chalk 3.3 cm thick, olive gray (5Y4/1), relatively hard, brittle, speckled throughout, not obviously laminated | | 4.5 |
| 9. | Chalk, olive gray (5Y4/1), relatively hard, brittle, calcareous silty, speckled throughout, not obviously laminated, has good fissility, weathers spally. FOSSILS: teleost bones and scales | | 19.8 |
| 8. | Bentonite, light brown (5YR5/6) to dark yellowish orange, moderately silty, with soft, plastic consistency, associated with minor amount of granular selenite | | 0.3 |
| 7. | Chalk, olive gray, as in unit 9. Prominent line lies 48.8 cm above base. FOSSILS: teleost scales | | 80.8 |
| 6. | Bentonite, two seams, separated by chalk. Lower seam 0.3 cm thick; upper seam 0.6 cm thick, moderately silty; both consist mainly of granular gypsum, which contains flakes of light brown (5YR5/6) to dark yellowish orange flakes of bentonite. Chalk is 2.2 cm thick, weathers shaly | | 3.1 |
| 5. | Chalk, as in unit 9. FOSSILS: I. (Platyceramus) platinus, ostreids, teleost bones and scales | | 74.8 |
| 4. | Bentonite, light gray, weathers dark yellowish orange, brittle, very silty, bounded by seams of granular selenite | | 0.9 |
| 3. | Chalk, as in unit 9. FOSSILS: teleost bones and scales | | 47.2 |
| 2. | Bentonite, mostly yellowish gray (5Y7/2); seam consists mostly of granular selenite, with minor iron oxide | | 0.3 |
| 1. | Chalk, as in unit 9. FOSSILS: ostreid bivalves | 1 | 28.0 |
| Measured thickness of Smoky Hill Member | 24 | 93.1 |
| Total thickness of measured section | 25 | 25.6 |
| LOCALITY 25--Section exposed in small butte in SE Sec. 30, T. 15 S., R. 32 W., Logan County, Kansas. |
Thickness |
| m |
cm |
| SMOKY HILL CHALK MEMBER |
| 32. | Bentonite, weathered, dark yellowish orange, waxy | | 0.9 |
| 31. | Chalk, highly weathered to dark yellowish orange to grayish orange | | 3.9 |
| 30. | Bentonite, weathered, dark yellowish orange, waxy | | 0.6 |
| 29. | Chalk, highly weathered | | 18.3 |
| 28. | Bentonite, weathered, dark yellowish orange, waxy | | 0.6 |
| 27. | Chalk, highly weathered, rather massive, cliff-forming bed | | 71.5 |
| 26. | Bentonite, mostly dark yellowish orange, silty, waxy, limonitic, with some crystalline selenite | | 0.3 |
| 25. | Chalk, weathered, dark yellowish orange to grayish orange, punky, calcareous silty, speckled throughout | | 2.2 |
| 24. | Bentonite, weathered, moderate yellowish brown, contains much limonite | | 0.3 |
| 23. | Chalk, weathered, pale yellowish orange to very light brown (5YR6/6), calcareous silty, speckled throughout, in part well laminated; where nonlaminated splits roughly parallel to bedding, where laminated splits evenly along bedding; prominent lines, not associated with bentonite, lie 31.5 cm above base and 15.2 cm below top. Unit forms part of nearly vertical cliff. FOSSILS: teleost bones and scales | | 68.6 |
| 22. | Bentonite, moderate yellowish brown, silty, appears earthy, waxy, contains minor amount of limonite | | 0.6 |
| 21. | Chalk, weathered, dark yellowish orange to pale grayish orange (10YR8/4), soft, punky, apparently well laminated, splits evenly parallel to bedding, calcareous silty, speckled throughout, with banded appearance owing to weathering. Unit forms rounded ledge. FOSSILS: Pseudoperna congesta, teleost bones and scales | | 42.2 |
| 20. | Bentonite, light brown (5YR5/6), silty, occurs as flakes in seam consisting mostly of limonite | | 0.3 |
| 19. | Chalk, weathered, dark yellowish orange to dark grayish orange (10YR6/4), apparently well laminated except for central part, splits evenly along laminae. Central 16.8 cm tough, granular, splits crudely along bedding, with faintly crinkled appearance. All rock calcareous silty, speckled, locally weathers shaly. Unit contains ferruginous streak 38.1 cm above base. Unit forms part of vertical cliff. FOSSILS: Pseudoperna congesta, Inoceramus balticus?, teleost bones and scales | | 58.0 |
| 18. | Ferruginous streak, easily traceable, possibly marks position of weathered bentonite seam | | 0.0 |
| 17. | Chalk, weathered, dark grayish orange (10YR6/4) to moderate yellowish brown, streaked with yellowish gray to pinkish gray, relatively soft, apparently well laminated throughout, splits easily parallel to bedding, weathers somewhat shaly, passes laterally to somewhat more brittle rock, calcareous silty, speckled throughout, forms vertical face locally. FOSSILS: Inoceramus balticus, Pseudoperna congesta, teleost scales | | 74.7 |
| 16. | Bentonite, dark yellowish brown, waxy, limonite stained | | 0.1 |
| 15. | Chalk, weathered, very pale yellowish brown (10YR7/2) to dark yellowish orange, mostly well laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, locally quite brittle and forms part of vertical cliff. FOSSILS: inoceramid fragments, teleost bones and scales | | 67.0 |
| 14. | Bentonite, dark yellowish brown, silty, with local concentrations of limonite | | 0.02 |
| 13. | Chalk, weathered, very pale yellowish brown (10YR7/2), surface dries very light gray, mostly well laminated; upper 6 cm tough and nonlaminated, weathers shalier than laminated part; speckled throughout, calcareous silty. Unit forms slope where least weathered and is part of steep cliff where much weathered. FOSSILS: Pseudoperna congesta, teleost scales | | 27.5 |
| 12. | Bentonite, moderate olive brown, non silty, waxy, forms prominent reentrant in cliff sections | | 0.03 |
| 11. | Chalk, weathered, very pale yellowish brown (10YR7/2) with streaks of dark yellowish orange, calcareous silty, speckled throughout; lowest 26 cm and uppermost 10.5 cm thinly laminated; interval from 26 to 38.3 cm above base is not obviously laminated, weathers out as massive, smooth-surfaced shoulder on slope. Band of ferruginous matter lies within uppermost 3 cm. Unit has sharp upper and lower contacts and is conspicuous on face of exposure. FOSSILS: Inoceramus balticus, Pseudoperna congesta, teleost bones and scales | | 48.8 |
| 10. | Chalk, weathered, grayish orange to pale grayish orange (10YR8/4), massive, very calcareous gritty, speckled throughout, tough, granular, forms smoothly rounded ledge, rock splits roughly parallel to bedding. Faint line, not associated with bedding, lies 62.6 cm above base. FOSSILS: Inoceramus balticus, Pseudoperna congesta, teleost bones and scales | | 94.7 |
| 9. | Bentonite, moderate yellowish brown, nonsilty, waxy, 1.2 cm thick, bordered by seams of coarsely crystalline selenite | | 2.8 |
| 8. | Chalk, weathered, pale grayish orange (10YR8/4), soft, calcareous silty, speckled throughout, nonlaminated, with units 7 and 9 forms prominent reentrant beneath unit 10 | | 5.2 |
| 7. | Bentonite, light brown (5YR5/6), as small flakes scattered through seam consisting almost entirely of very coarsely crystalline selenite | | 1.2 |
| 6. | Chalk, weathered, medium yellowish orange (1 OYR 7/6), nonlaminated, speckled throughout; basal 6.2 cm and upper 12.2 cm soft, weather shaly; middle part tough, granular, forms smooth slope and locally projecting ledge. Shaly part splits evenly parallel to bedding. FOSSILS: teleost bones and scales | | 44.2 |
| 5. | Ferruginous seam, dark yellowish orange, not associated with bentonite | | 0.1 |
| 4. | Chalk, weathered, dark yellowish orange to very light brown (5YR6/6), rather punky, calcareous silty, speckled throughout, not obviously laminated, splits unevenly along bedding, forms minor ledge. FOSSILS: teleost bones and scales | | 25.9 |
| 3. | Bentonite, yellowish gray (5Y7/2) to dusky yellow, slightly silty, waxy, with limonite along joints and fractures | | 11.6 |
| 2. | Chalk, weathered, dark yellowish orange to light brown (10YR5/6), rather punky, not obviously laminated, calcareous silty, speckled throughout, forms smoothly convex slope, weathers shaly. FOSSILS: Pseudoperna congesta, teleost bones and scales | | 48.8 |
| 1. | Bentonite, light olive gray (5Y7/2), almost non silty , waxy, limonite stained, with a little associated gypsum | | 6.0 |
| Total thickness of measured section | 7 | 27.0 |
| LOCALITY 24--Section exposed along cliffs and gullies in bluff on east side of Ladder Creek, in SW Sec. 30, T. 15 S., R. 32 W., Logan County, Kansas. |
Thickness |
| m |
cm |
| SMOKY HILL CHALK MEMBER |
| 61. | Chalk, much weathered; contains large, oblate spheroidal nodules of chert (formed by secondary processes) adjacent to contact with overlying Ogallala Formation. Unit forms part of vertical cliff. Thickness approximately | 1 | 63.0 |
| 60. | Bentonite, light greenish gray, almost nonsilty, earthy to waxy, limonite-stained on fractures, forms deep reentrant on cliff face | | 0.3 |
| 59. | Chalk, weathered medium yellowish orange (10YR7/6) to moderate reddish orange, relatively soft, not obviously laminated, splits generally parallel to bedding, calcareous silty, speckled throughout. Unit contains large masses of liesegang-banded chert. Unit forms part of vertical cliff. FOSSILS: teleost scales | 1 | 46.3 |
| 58. | Bentonite, yellowish gray (5Y8/1), nonsilty, waxy, forms prominent reentrant on slope | | 1.3 |
| 57. | Chalk, weathered pale brown (5YR7/6) to dark yellowish orange, soft, not obviously laminated, streaked locally by horizontal white bands, breaks blocky. FOSSILS: teleost bones and scales | | 5.5 |
| 56. | Bentonite, light brown (5YR5/6), mostly limonite, forms conspicuous reentrant on cliff face | | 0.1 |
| 55. | Chalk, weathered grayish orange, soft, not obviously laminated, splits evenly parallel to bedding, calcareous silty, speckled throughout, forms part of vertical cliff. Streaked with horizontal white bands near top. FOSSILS: teleost bones and scales | | 33.6 |
| 54. | Ferruginous seam, dark yellowish orange, forms prominent reentrant of cliff face; unit climbs laterally to position 48.7 cm above top of unit 53, so is probably not a stratigraphic feature | | 0.1 |
| 53. | Chalk, like unit 55, forms part of vertical cliff, locally iron-oxide-banded in upper part; unit contains prominent line, marked by minor seam of iron oxide, 10.7 cm above base. FOSSILS: teleost bones and scales | | 25.9 |
| 52. | Bentonite, pale olive, dries light greenish gray (5GY8/1), earthy to waxy, very silty, forms prominent reentrant on cliff face | | 9.7 |
| 51. | Chalk, weathered dark yellowish orange, soft, punky, not obviously laminated, splits evenly parallel to bedding, calcareous silty, speckled throughout, forms rounded ledge to somewhat shaly weathering slope. FOSSILS: Pseudoperna congesta, teleost scales | | 33.5 |
| 50. | Bentonite, dark yellowish orange, slightly silty, waxy, forms prominent reentrant on cliff face | | 5.2 |
| 49. | Chalk, mostly weathered dark yellowish orange with color banding owing to weathering; not obviously laminated, splits evenly parallel to bedding, relatively soft, somewhat punky, calcareous silty, speckled throughout, with color banding owing to weathering. Unit forms part of cliff at top of section. FOSSILS: Pseudoperna congesta, teleost bones and scales | | 97.5 |
| 48. | Bentonite, very pale yellowish brown (10YR7/2), almost nonsilty, waxy, iron-stained | | 1.5 |
| 47. | Chalk, mostly weathered very pale orange, not obviously laminated but parts of unit are color banded owing to weathering, relatively brittle, calcareous silty, speckled throughout, forms nearly vertical face, weathers to thin, flat slabs. Unit contains prominent lines, possibly marking very thin weathered bentonite seams, 13.0 cm and 16.4 cm above base; prominent reentrant marks a third line lying 53.3 cm above base. FOSSILS: Pseudoperna congesta, teleost bones and scales | 1 | 12.8 |
| 46. | Bentonite, light brown (5YR5/6), earthy to waxy, limonitic, silty | | 0.6 |
| 45. | Chalk, weathered pale yellowish orange, has granular texture, apparently massive, splits roughly parallel to bedding, soft, calcareous silty, speckled throughout, forms vertical face. Laterally, unit passes into soft, shaly weathering chalk. FOSSILS: Inoceramus (Platyceramus) platinus?, Pseudoperna congesta, teleost scales | | 21.4 |
| 44. | Bentonite, light brown (5YR5/6) to dark yellowish brown, limonite-stained, slightly silty, waxy | | 3.1 |
| 43. | Chalk, weathered dark yellowish orange to medium yellowish orange (10YR7/6), with band of moderate reddish orange coloration, 7.6 to 13.7 cm thick, along center of unit. Faintly liesegang(?)-banded, but not obviously laminated; rock splits roughly parallel to bedding. Unit marked by three prominent lines, each marked by small concentration of limonite, which lie 9.7, 17.3, and 30.7 cm above base. FOSSILS: Pseudoperna congesta, teleost scales and bones | | 73.1 |
| 42. | Bentonite, grayish yellow (5Y8/4) to yellowish gray (5Y7/2), slightly silty, waxy, limonite-stained | | 2.1 |
| 41. | Chalk, weathered dark yellowish orange, granular, not obviously laminated, splits evenly parallel to bedding, calcareous silty, speckled, forms part of steep cliff face, weathers shaly and forms slope where most intensively weathered. Unit divided into three beds of subequal thickness by two 3-cm-thick darker-colored zones with crinkly structure. Possible weathered bentonite seam lies 9.1 cm below top. FOSSILS: Pseudoperna congesta, teleost bones | | 41.2 |
| 40. | Bentonite, light olive gray (5Y6/l) to greenish gray, very silty, earthy to waxy | | 0.3 |
| 39. | Chalk, weathered dark yellowish orange, granular, not obviously laminated, splits easily parallel to bedding, calcareous silty, speckled, liesegang-banded in lower half. FOSSILS: Pseudoperna congesta, teleost bones and scales | | 9.1 |
| 38. | Bentonite, yellowish gray (5Y7/2), slightly silty, waxy, with some limonite staining | | 4.6 |
| 37. | Chalk, weathered dark yellowish orange to grayish orange, granular, not obviously laminated, splits easily parallel to bedding, calcareous silty, speckled throughout. FOSSILS: Pseudoperna congesta, teleost bones and scales | | 12.2 |
| 36. | Bentonite, light gray to light brown (5YR5/6); seam composed mostly of limonite | | 0.02 |
| 35. | Chalk, as in unit 37, tough, granular, weathers shaly, with liesegang banding in lower part. FOSSILS: Pseudoperna congesta, teleost bones and scales | | 27.4 |
| 34. | Bentonite, light olive brown, with pale olive brown (5Y6/6) stains, almost nonsilty, waxy | | 2.1 |
| 33. | Chalk, weathered grayish orange, tough, granular, not obviously laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, forms rounded ledge. Upper part of unit softer, weathers shaly, dark yellowish orange to very pale orange, streaked with pale bluish gray (5B8/1), calcareous silty, speckled, splits easily along bedding. FOSSILS: teleost scales and bones | | 33.5 |
| 32. | Bentonite, light brown (5YR5/6), as a few flakes scattered in a seam consisting mostly of limonite | | 0.3 |
| 31. | Chalk, partly weathered to moderate yellowish brown to medium yellowish brown with streaks of light olive gray (5Y512), tough, faintly laminated, splits easily along bedding, calcareous silty, weathers shaly. FOSSILS: Pseudoperna congesta, teleost bones and scales | | 42.7 |
| 30. | Chalk and five weathered bentonite seams. Chalk partly weathered to medium olive gray (5Y4/2) to yellowish gray (5Y7/2), mostly with crinkly structure. Uppermost chalk bed dries to conspicuous pale bluish gray (5B8/1), laminated, forms distinctive marker. Other chalk beds in part laminated. All chalk calcareous silty, speckled, splits easily parallel to bedding. Bentonite? seams represented mostly by iron oxide; lowest seam consists largely of powdery gypsum; uppermost seam locally 0.6 cm thick, light olive brown, bentonitic | | 35.0 |
| 29. | Chalk, dark olive gray to olive gray (5Y4/1), weathers medium yellowish brown (10YR5/2). Lower 1.62 cm comprises tough, granular chalk with some crinkly structure; forms steep, spally weathering face, with uppermost portion forming smoothly rounded, lighter-colored shoulder; not obviously laminated, but has stratified appearance; calcareous silty, speckled throughout. Uppermost 54.9 cm is olive gray (5Y4/1), calcareous silty, speckled, with crinkly structure, less resistant than lower part. Entire unit weathers shaly. Prominent line, parallel to bedding, lies 7.6 cm below top. FOSSILS: I. ?(Platyceramus) platinus, Pseudoperna congesta, teleost bones and scales | 2 | 16.7 |
| 28. | Bentonite, moderate yellowish brown, silty, as flakes scattered in seam consisting mostly of coarsely crystalline selenite and powdery gypsum. Seam expands locally to 1.8 cm where much weathered | | 0.6 |
| 27. | Chalk, olive gray (5Y4/1), weathering medium yellowish brown (10YR5/2), tough, granular, calcareous silty, speckled, with central zone of crinkly structure, forms gently shouldered slope; where highly weathered forms shaly slope with two lighter-colored, more resistant zones at top and base. FOSSILS: I. ?(Platyceramus) platinus, Pseudoperna congesta, teleost scales and bones | | 45.7 |
| 26. | Ferruginous seam, moderate yellowish brown, limonitic, expands locally to 1.3 cm where mineralized with gypsum | | 0.3 |
| 25. | Chalk, olive gray (5Y4/1) to medium olive gray (5Y4/2), very tough, granular, nonlaminated, splits unevenly parallel to bedding, calcareous silty, speckled throughout; uppermost 9.1 cm with crinkly structure, remainder with sparse crinkly structure; weathers shaly. FOSSILS: I. ?(Platyceramus) platinus, coprolite, teleost bones and scales | | 18.3 |
| 24. | Bentonite, mostly grayish orange medium-crystalline selenite, with scattered flakes of silty bentonite, which are dark yellowish brown. Where weathered, seam expands to 1.5 cm and is heavily mineralized by selenite | | 0.6 |
| 23. | Chalk, olive gray (5Y4/1), forms darker-colored band on slope, calcareous silty, speckled, with crinkly structure; weathers shaly. FOSSILS: Pseudoperna congesta, coprolite | | 6.1 |
| 22. | Bentonite, pale grayish orange (10YR8/4), with seam of limonite forming top of unit, expands laterally to 3 cm owing to secondary mineralization; actual bentonite seam 1.2 cm thick | | 1.8 |
| 21. | Chalk, olive gray (5Y4/1), weathers dark yellowish orange, mostly tough, granular, nonlaminated, in part solution-crinkled, forms gently rounded shoulders on slope, with thin, softer interval of darker chalk with crinkly structure near center. Upper 9.2 cm olive gray (5Y4/1) to medium olive gray (5Y412), highly solution-crinkled, forms distinctly darker band on weathered face. All rock calcareous silty, speckled throughout, splits parallel to bedding. FOSSILS: inoceramid valves, Pseudoperna congesta, teleost scales and bones | | 76.3 |
| 20. | Bentonite, dark yellowish orange, silty; seam consists mostly of crystalline selenite, with local concentrations of powdery gypsum | | 0.6 |
| 19. | Chalk, dark olive gray (5Y3/1), or partly weathered to medium olive gray (5Y4/2); mostly tough, granular chalk, which is hard and brittle where least weathered, lighter colored where partially weathered; calcareous silty, speckled throughout, nonlaminated, splits parallel to bedding; locally forms steep, spally face; elsewhere weathers shaly. Unit contains scattered crinkly structure. FOSSILS: Pseudoperna congesta, teleost bones and scales | | 64.0 |
| 18. | Bentonite, grayish orange, slightly silty; actual bentonite seam 0.9 cm thick, bordered by projecting ledges of hard limonite of subequal thickness. Seam hosts local nodules of limonite that contain gypsum and jarosite | | 3.4 |
| 17. | Chalk, moderate yellowish brown (10YR512), not obviously laminated, splits easily along bedding, calcareous silty, speckled throughout, weathers spally in steep faces, weathers shaly elsewhere. FOSSILS: teleost bones and scales | | 29.0 |
| 16. | Bentonite, light brown (5YR5/6), associated with underlying seam of crystalline gypsum; actual bentonite seam 0.1 cm thick | | 0.9 |
| 15. | Chalk, olive gray (5Y4/1) to dark olive gray (5Y3/1), relatively hard, brittle, not obviously laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, weathers spally in steep faces, weathers soft and shaly elsewhere. Unit contains scattered zones of crinkly structure. FOSSILS: inoceramid fragments: Pseudoperna congesta, teleost bones and scales | 1 | 44.3 |
| 14. | Ferruginous seam, mostly light brown (10YR5/6), hosts isolated nodules of limonite. (In fresh, unweathered exposures this seam is not detectable.) | | 0.2 |
| 13. | Chalk, olive gray (5Y4/1), or partly weathered light olive gray (5Y5/2), relatively hard, brittle, not obviously laminated, splits easily parallel to bedding, calcareous silty, speckled, locally forms steep, spally face, weathers soft and shaly. Unit has sparse crinkly structure. FOSSILS: coprolite, teleost scales and bones | 1 | 13.0 |
| 12. | Ferruginous seam, moderate yellowish brown (10YR5/2), hosts numerous limonite nodules | | 0.3 |
| 11. | Chalk, medium gray to olive gray (5Y4/1) or medium olive gray (5Y5/1), relatively hard, brittle, not obviously laminated, splits easily along bedding, calcareous silty, speckled throughout, forms steep spally face, in part with crinkly structure, weathers soft and shaly. FOSSILS: Pseudoperna congesta | | 61.0 |
| 10. | Bentonite, very pale orange, slightly silty, partly stained dark yellowish orange by limonite, bordered by subequal seams of limonite that form projecting ledges. Actual bentonite seam 4.0 cm thick | | 6.1 |
| 9. | Chalk, as alternating beds of lighter-colored granular and darker-colored chalk with crinkly structure. Granular chalk very tough, medium olive gray (5Y5/1), nonlaminated, calcareous silty, speckled throughout, in beds as much as 18 cm in thickness. Crinkly chalk olive gray (5Y4/1) to medium olive gray (5Y4/2), calcareous silty, speckled throughout, not obviously laminated, splits parallel to bedding, locally forms spally faces, weathers shaly. Ferruginous seams, less than 0.1 cm thick and marked by rows of oblate spheroidal limonite nodules, lie 94.6 cm and 1.16 m below top of unit. Granular and shaly weathering chalk beds gradational. FOSSILS: Pseudoperna congesta | 1 | 86.0 |
| 8. | Bentonite, grayish orange, much stained by limonite, gritty (disseminated gypsum crystals), passes laterally into seam heavily mineralized by limonite | | 0.2 |
| 7. | Chalk, as alternating beds of lighter-colored granular and darker-colored chalk, both with crinkly structure. Granular chalk olive gray (5Y5/2) to dark olive gray (5Y3/1), tough, calcareous silty, speckled throughout, medium yellowish brown (10YR5/2) where partly weathered, forms four distinct bands on slope, maximum thickness 15.2 cm, with some crinkly structure. Darker chalk olive gray (5Y5/2) to dark olive gray (5Y3/1), relatively hard, calcareous silty, speckled throughout, not obviously laminated, splits easily parallel to bedding, much crinkly structure in upper 39.5 cm, forms steep spally faces, weathers shaly. Conspicuously darker, organic-rich bed, 10.5 cm thick, lies 35 cm below top. Granular and shaly weathering chalk beds gradational. Ferruginous-gypsiferous seam, 0.1 cm thick, locally hosts small limonite nodules, lies 70.2 cm below top of unit. FOSSILS: teleost bones | 2 | 32.0 |
| 6. | Bentonite; seam consists mostly of moderate yellowish brown (10YR5/2) granular gypsum, locally hosts oblate spheroidal masses of dark yellowish orange to light brown (5Y5/6) limonite/jarosite/gypsum as much as 33.5 cm wide and 6 cm thick | | 0.3 |
| 5. | Chalk, medium olive gray (5Y4/2), slightly calcareous silty, speckled throughout, weathers shaly, with crinkly structure | | 12.2 |
| 4. | Bentonite, yellowish gray (5Y7/2), in part limonite-stained, bordered by equal thicknesses of dark yellowish brown limonite. Actual bentonite seam is 0.5 cm thick | | 3.0 |
| 3. | Chalk, medium light gray to light olive gray (5Y5/2), not obviously laminated, splits easily parallel to bedding, with crinkly structure, forms spally faces, weathers shaly. Unit contains two beds of lighter-colored granular chalk, 27.5 cm and 12.2 cm thick, lying 24.4 cm and 1 m above base of unit, respectively, very tough, calcareous silty, speckled throughout, appears crudely stratified, forms gently convex shoulders on moderate slopes, gradational with darker-colored chalk. FOSSILS: teleost scales | 1 | 61.8 |
| 2. | Bentonite, very pale orange, very silty, with sour taste, mineralized along contacts by limonite/jarosite/selenite, locally hosts oblate spheroidal limonitic nodules that have rotten marcasite in center. Actual bentonite seam is 0.9 cm thick | | 1.2 |
| 1. | Chalk, olive gray (5Y4/1), hard, brittle, not obviously laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, forms steep spally face, weathers shaly, contains widely scattered, weathered pyrite nodules 70 cm below top. Unit contains two beds of lighter-colored, tough granular chalk, 3.1 cm and 30.5 cm thick, lying 93.1 cm and 1.7 m above base; both beds form gently convex shoulders on slope | 1 | 46.5 |
| Total thickness of measured section | 24 | 77.4 |
| LOCALITY 20--Cliffs along bluff on south side of Twin Butte Creek, in SW Sec. 16, T. 15 S., R. 34 W., Logan County, Kansas. |
Thickness |
| m |
cm |
| SMOKY HILL CHALK MEMBER |
| 25. | Highly weathered chalk extending to top of bluff | | |
| 24. | Bentonite, very pale orange, silty; seam hosts hollow, gypsiferous geode-like structures. Seam heavily mineralized by selenite and limonite, which form hard, projecting ledges above and below bentonite, and with bentonite forming unit as much as 13.5 cm thick | | 3.7 |
| 23. | Chalk, as alternation of tough, lighter-colored granular chalk and darker-colored chalk with crinkly structure. Granular chalk is partly weathered, pale yellowish brown, calcareous silty, speckled throughout. Darker-colored chalk is partly weathered, dark yellowish brown, calcareous silty, speckled, with crinkly structure, weathers to fine flakes. Entire unit has horizontally banded appearance. Layer of small limonite/marcasite nodules centers 55 cm below top of unit. FOSSILS: Pseudoperna congesta, teleost scales and bones | 1 | 11.4 |
| 22. | Gypsum, mostly granular selenite, characterized by oblate spheroidal limonite/marcasite nodules as much as 24.5 cm in diameter | | 0.6 |
| 21. | Chalk, olive gray (5Y4/1), somewhat laminated in appearance, calcareous silty, much speckled, fissile, weathers shaly, with some crinkly structure. Contains several beds, as much as 0.9 cm thick, of harder chalk. Unit mostly soft and crumbly. FOSSILS:Pseudoperna congesta, coprolite | | 32.1 |
| 20. | Bentonite, light brown (10YR5/6); seam consists mostly of limonite, with some jarosite, and small limonitic nodules. Mineralized part of seam projects as ledge locally. Actual bentonite seam 0.01 cm thick | | 0.6 |
| 19. | Chalk, all partly weathered, comprises alternation of lighter- and darker-colored beds that impart banded appearance to exposure. Darker beds medium yellowish brown (10YR5/2) to very dark yellowish brown (10YR312), calcareous silty, much speckled, with crinkly structure, fissile, weathers minutely flaky. Lighter-colored unit, light olive gray (5Y5/2) to pale yellowish brown, tough, calcareous silty, much speckled, with sparse crinkly structure. Seam of secondary selenite, 0.6 cm thick, lying 1.9 m above base, hosts small limonite nodules. Second selenite seam, 0.6 cm thick, lying 1.76 m above base, with associated limonitic nodules, contains film of bentonite at top. Limonitic seam, 0.3 cm thick, lying 1.61 m above base, associated with jarosite and granular gypsum, hosts oblate spheroidal limonitel marcasite nodules as much as 39.6 cm in diameter and 9.1 cm thick. FOSSILS: Pseudoperna congesta, teleost bones | 4 | 0.0 |
| 18. | Ferruginous/gypsiferous seam, dark yellowish orange | | 0.6 |
| 17. | Chalk, all partly weathered, light olive gray (5Y6/1) to pale yellowish brown, not obviously laminated, breaks blocky, calcareous silty, speckled throughout, forms gently sloped, curved face, weathers shaly. FOSSILS: Inoceramus fragments, Pseudoperna congesta, teleost bones and scales | | 64.4 |
| 16. | Bentonite, grayish orange, silty; unit consists mostly of iron oxide and granular selenite; actual bentonite seam approximately 0.5 cm thick | | 2.9 |
| 15. | Chalk, all partly weathered, olive gray (5Y5/2), pale yellowish brown and grayish orange, not obviously laminated, fissile, breaks blocky, calcareous silty, speckled throughout, soft and punky where moist, forms gently shouldered slopes on part of steep cliff face. Unit appears well stratified. FOSSILS: Inoceramus sp., Baculites?, teleost scales and bones | 1 | 83.0 |
| 14. | Bentonite, white, brittle; lower part of unit consists mostly of dark yellowish orange limonite and gypsum; upper part mostly medium to coarse crystals of selenite | | 2.5 |
| 13. | Chalk, partly weathered, medium olive gray (5Y4/2) to light olive gray (5Y512), obscurely to well laminated, fissile, calcareous silty, speckled throughout, tough, softer where weathered, forms smoothly shouldered slope, weathers flaky. Unit well laminated in interval 49 cm thick that lies 1.7 m below top, and within uppermost 52 cm. Granular chalk, light olive gray (5Y5/2), much tougher than flaky weathering chalk, faintly stratified, as three conspicuous beds 21.2 cm, 8.2 cm, and 4.5 cm thick and lying 96 cm, 3.1 m, and 6.7 m above base, respectively, forms more resistant, convex shoulders on slope; imparts widely banded appearance to unit. Bed of conspicuously darker chalk, 48.8 cm thick, dark yellowish brown, lies directly beneath uppermost bed of light-colored chalk. FOSSILS: Inoceramus (Platyceramus) platinus, Pseudoperna congesta, acrothoracican borings, teleost bones and scales; many inoceramids pyritized extensively | 7 | 22.5 |
| 12. | Bentonite?, dark yellowish orange; seam consists mostly of selenite and limonite; mineralization thickens unit locally to 7.6 cm. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta in limonite mass associated with seam | | 0.6 |
| 11. | Chalk, medium olive gray (5Y5/1) to olive gray (5Y4/1), in part weathered light olive gray (5Y5/2), obscurely laminated, in part well laminated where exposed in vertical faces, calcareous silty, speckled throughout, forms vertical spally faces, weathers flaky. Granular chalk, very tough, nonlaminated, in bed 36.6 cm thick, lies 73.2 cm below the top. Very faint ferruginous seam lies 76.2 cm above base; second faint ferruginous seam lies 1.1 m below top of unit. Lower 1.5 m contains scattered polycuboidal pyrite nodules, some of which are much limonitized. Some large inoceramids are pyritized, now altered to limonite, and host nodules of rotten marcasite. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, teleost bones | 4 | 14.6 |
| 10. | Bentonite, pale grayish orange (10YR8/4), with light brown (5YR5/6) iron oxide stains, brittle, very silty. Iron oxide and finely granular gypsum comprise about half of unit | | 1.2 |
| 9. | Chalk, most partly weathered, medium olive gray (5Y4/2), yellowish gray (5Y7/2), and light olive gray (5Y5/2), obscurely to well laminated, mostly fissile, brittle or tough, calcareous silty, speckled throughout. Organic-rich chalk, dark yellowish brown, 27.4 cm thick, lies 30.5 cm above base, forms conspicuous marker on little-weathered surfaces. Ferruginous/gypsiferous seam, 0.1 cm thick, lies 12 cm below top. Unit contains scattered polycuboidal nodules of pyrite and widely scattered limonitized marcasite nodules as much as 1.07 m wide and 10.5 cm thick, many of which are localized around inoceramid valves. Inoceramids mostly limonitized. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, Baculites sp. (smooth molds), teleost scales and bones | 3 | 47.5 |
| 8. | Bentonite, dark yellowish orange, as a very thin film at top of unit, which consists mostly of powdery and finely granular gypsum, with minor iron oxide | | 0.6 |
| 7. | Chalk, partly weathered, medium yellowish brown (10YR5/2) 10 grayish orange, tough, brittle, not obviously laminated, fissile, weathers flaky. FOSSILS: Inoceramus sp. (mold), Pseudoperna congesta | | 21.3 |
| 6. | Bentonite, dark yellowish orange, very silty, as flakes scattered throughout seam consisting mostly of limonite and finely granular gypsum. Unit expands locally to 1.5 cm; locally hosts limonite/jarosite/marcasite nodules | | 0.6 |
| 5. | Chalk, partly weathered, medium olive gray (5Y5/1) to light olive gray (5Y6/1), tough, not obviously laminated, fissile, calcareous silty, speckled throughout, weathers flaky. Unit contains widely scattered limonite/marcasite nodules as much as 15.2 cm in diameter, and much platy selenite. FOSSILS: Inoceramus balticus?, I. (Platyceramus) platinus, Pseudoperna congesta, large vertebrate tooth | 1 | 9.0 |
| 4. | Bentonite, dark yellowish orange, silty, as very thin films at top and base of unit. Unit consists mostly of powdery and crystalline gypsum, hosts abundant oblate spheroidal limonite/marcasite nodules | | 0.9 |
| 3. | Chalk, partly weathered, medium olive gray (5Y5/1), light olive gray (5Y6/1), and moderate yellowish brown (10YR5/2), tough, brittle, obscurely laminated, fissile, calcareous silty, speckled throughout, weathers flaky, much powdery gypsum throughout. Unit contains scattered marcasite limonite/jarosite nodules. FOSSILS: Inoceramus balticus?, Inoceramus sp., Pseudoperna congesta, Baculites sp. (smooth mold) | 1 | 92.2 |
| 2. | Bentonite, light brown (5YR5/6), silty, in seam consisting mostly of powdery to medium crystalline selenite in lower part, and limonite in upper part. Thickness locally to 1.5 cm | | 0.6 |
| 1. | Chalk, partly weathered, very pale yellowish brown (10YR7/2), to light olive gray (5Y6/1), laminated, fissile, calcareous silty, speckled throughout | | 33.5 |
| Total thickness of measured section | 26 | 46.9 |
| LOCALITY 23--Bluffs along small southern tributary to Smoky Hill River, in SW Sec. 7, T. 15 S., R. 31 W., Gove County, Kansas, and SE Sec. 12, T. 15 S., R. 32 W., Logan County, Kansas. |
Thickness |
| m |
cm |
| SMOKY HILL CHALK MEMBER |
| 32. | Chalk, much weathered, pale orange (10YR712) to very pale orange, soft and punky to relatively brittle, not obviously laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, harder part lichen-splotched. Unit forms caprock at top of bluff. FOSSILS: Inoceramus sp. (mold), Pseudoperna congesta, teleost bones and scales | | 97.5 |
| 31. | Bentonite, nearly white to very pale orange, slightly silty, waxy, comprises about half of unit thickness, remainder of which is limonite and jarosite. Unit forms prominent reentrant on cliff face | | 0.6 |
| 30. | Chalk, partly weathered, light olive gray (5Y6/1), grading upward to medium yellowish brown (10YR5/2) and finally to grayish orange, all relatively tough and brittle, most is not obviously laminated but unit has generally well-stratified appearance overall, breaks parallel to bedding, calcareous silty, speckled, weathers shaly. Unit contains three beds of granular chalk, 18.3, 15.2, and 33.6 cm thick lying 1.37 m, 2.35 m, and 3.87 m above base, respectively, medium yellowish brown (10YR5/2) to yellowish gray (5Y7/2), tough, nonlaminated, breaks crudely parallel 10 bedding, calcareous silty, speckled throughout, forms distinctive light-colored bands on slope. Many large inoceramids host limonite/jarosite nodules with rotten marcasite centers, as much as 24.5 cm in diameter, throughout unit. Prominent zone of large inoceramids 6 cm thick lies 1.32 m above base. Faint streaks marked by thin crusts of limonite lie in zone 3.0 cm thick and 33.5 cm below top; zone hosts widely spaced crumbly marcasite nodules. FOSSILS: Inoceramus (Platyceramus) platinus, Pseudoperna congesta, Baculites sp. (smooth molds) | 4 | 90.8 |
| 29. | Bentonite, light brown (5YR5/6), silty, in seam consisting mostly of limonite and finely granular gypsum, which are concentrated at top and base of unit. Unit hosts limonitic masses, as much as 45.7 cm wide and 9.1 cm thick, which have rotten marcasite cores | | 0.9 |
| 28. | Chalk, partly weathered, light olive gray (5Y5/2) to yellowish gray (5Y7/2), not obviously laminated but appears bedded, most splits easily along bedding, calcareous silty, speckled. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, teleost scales and bones | | 12.2 |
| 27. | Ferruginous seam, mostly limonite and jarosite, with some granular gypsum. Seam expands locally to 2.5 cm | | 0.2 |
| 26. | Chalk, mostly partly weathered, dark yellowish brown 10 pale yellowish brown or light olive gray (5Y6/1) above, tough, obscurely to nonlaminated, splits easily parallel to bedding, calcareous silty, speckled throughout, weathers shaly. Bed of organic-rich chalk, olive gray (5Y4/1), 18.3 cm thick, lies 41.2 cm above base, forms conspicuous dark-colored band on slope. Granular chalk, medium yellowish brown (10YR5/2), tough, nonlaminated, speckled throughout; in three beds 49.0, 6.1, and 15.2 cm thick; lying 1.0 m above base, 76.2 cm below top, and at top of unit, respectively. Granular chalk dries to lighter color than remainder of unit and forms conspicuous bands on slope. Large inoceramids in unit commonly host masses of limonite/jarosite, which have rotten marcasite cores. Upper 1.22 m contains scattered nodules of pyrite. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, teleost bones and scales | 2 | 89.6 |
| 25. | Bentonite, light brown (5Y5/6), silty, as scattered flakes in seam consisting mostly of limonite and finely granular gypsum. Unit expands in thickness where more heavily mineralized | | 0.2 |
| 24. | Chalk, partly weathered, very pale yellowish brown (10YR7/2) to pale yellowish brown, tough, obscurely laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, weathers shaly, contains small limonite nodules with rotten marcasite cores. FOSSILS: I. ?(Platyceramus) platinus, Pseudoperna congesta, teleost bones and scales | | 18.3 |
| 23. | Bentonite, pale yellowish brown, in seam consisting mostly of limonite, jarosite, and selenite. Actual bentonite seam about 0.1 cm thick. Unit thickens to 3.4 cm where most heavily mineralized | | 1.5 |
| 22. | Chalk, partly weathered, medium olive gray (5Y412) to light olive gray (5Y5/2), relatively tough, not obviously laminated, splits easily parallel to bedding, calcareous silty, speckled throughout. Unit contains scattered limonite nodules, with rotten marcasite cores, some of which are localized around valves of large inoceramids. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta | 1 | 13.6 |
| 21. | Ferruginous/gypsiferous seam, dark yellowish orange, locally jarositic. Unit hosts limonite/jarosite/ gypsum nodules as much as 24.4 cm in diameter and 4.6 cm thick | | 1.2 |
| 20. | Chalk, partly weathered, medium olive gray (5Y4/1) to yellowish gray (5Y7/2), tough, in part obscurely laminated, calcareous silty, speckled throughout, weathers flaky. Lower 30 cm contains abundant invertebrate shells. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, sponge borings, Stramentum haworthi, teleost bones and scales | 1 | 61.8 |
| 19. | Ferruginous gypsum seam, dark yellowish orange, hosts limonite/jarosite/gypsum masses as much as 38 cm wide and 9.2 cm thick. Unit greatly thickened locally by addition of secondary mineral matter | | 0.3 |
| 18. | Chalk, partly weathered, medium yellowish brown (10YR5/2) to light olive gray (5Y5/2), more weathered rock grayish orange to very pale orange, tough, obscurely laminated to not obviously laminated, calcareous silty, speckled throughout, weathers flaky. Unit contains scattered limonite/jarosite nodules, with rotten marcasite cores, in zone 76.3 to 91.5 cm above base, and commonly localized around large inoceramid valves. Many inoceramid valves limonitized. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, teleost bones and scales | 1 | 16.9 |
| 17. | Bentonite, dark yellowish orange, in seam consisting mostly of limonite and gypsum. Unit hosts limonite/ jarosite/gypsum nodules. Bentonite is thin film at top of unit | | 1.2 |
| 16. | Chalk, weathered, grayish orange, soft, calcareous silty, speckled throughout, laminated, splits easily along bedding, weathers flaky. FOSSILS: tail of Xiphactinus at base | | 3.7 |
| 15. | Ferruginous gypsum seam, light brown (5YR5/6), comprises two layers of limonitic gypsum that embrace a central layer of limonite. Unit hosts abundant limonite/jarosite/gypsum nodules as much as 24.4 cm in diameter and 6.1 cm thick. Unit forms minor ledge, held up by platy masses of selenite | | 1.2 |
| 14. | Chalk, partly weathered, light olive gray (5Y512) to medium yellowish brown (10YR5/2) to yellowish gray (5Y7/2), relatively tough, in part well laminated, in part obscurely laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, weathers flaky. Unit contains widely scattered limonite nodules, with rotten marcasite cores, as much as 8.3 cm in diameter and 3.1 cm thick. FOSSILS: I. (Platyceramus) platinus, Inoceramus sp., Pseudoperna congesta, acrothoracican borings, Baculites sp. (smooth mold), Squalicorax tooth | 2 | 25.6 |
| 13. | Bentonite, light brown (5YR5/6), gritty, waxy, underlain by powdery to finely crystalline gypsum; actual bentonite is less than 0.1 cm thick. Unit hosts small nodules of limonite | | 0.6 |
| 12. | Chalk, partly weathered, medium yellowish brown to light olive gray (5Y5/2) to grayish orange, tough, poorly to well laminated, splits easily along bedding, calcareous silty, speckled throughout, weathers flaky. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, Inoceramus sp. (mold), teleost scales | 1 | 16.0 |
| 11. | Bentonite, grayish yellow, gritty, waxy, with strong taste of melanterite, bordered by seams of jarositeand limonite-stained selenite. Actual bentonite seam 1.2 cm thick. Unit hosts limonite nodules that have rotten marcasite centers. Unit forms projecting ledge where heavily mineralized; otherwise forms prominent band on slope | | 2.5 |
| 10. | Chalk, olive gray (5Y4/1), most partly weathered dark yellowish brown to grayish orange, tough, more or less well laminated, splits easily parallel to bedding, weathers flaky, contains scattered small limonite nodules. Zone of granular gypsum seams, 10 cm thick, lies 45.7 cm below top. Ferruginous/ gypsiferous seam, 0.6 cm thick, lies 30.5 cm below top. Unit contains scattered oblate spheroidal nodules oflimonite/jarosite/selenite, commonly with rotten marcasite cores which are especially common 1.07 m and 2.13 m above base. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, teleost bones and scales | 3 | 65.8 |
| 9. | Ferruginous/gypsiferous seam, light brown (5YR5/6), locally hosts limonite/jarosite masses as much as 1.8 cm thick | | 0.3 |
| 8. | Chalk, olive gray (5Y4/1), weathers light olive gray (5Y512, 5Y6/1), tough, in part well laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, weathers flaky. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, inoceramid fragments, phosphatic coprolite, teleost bones and scales | | 96.1 |
| 7. | Bentonite, yellowish gray (5Y7/2), slightly stained by light brown (5YR5/6) limonite, contains much jarosite, bordered above and below by limonite/ gypsum seams that form projecting ledges. Actual bentonite is 2.1 cm thick. Unit hosts limonite nodules, with rotten marcasite centers, which are as much as 24.5 cm in diameter and 6.1 cm thick | | 3.7 |
| 6. | Chalk, partly weathered, light olive gray (5Y5/2, 5Y6/1) to pale grayish orange, soft at surface, harder below, more or less laminated, contains sparse faint burrow structures but splits easily along bedding, calcareous silty, speckled throughout, weathers flaky. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, teleost scales and bones | 1 | 22.5 |
| 5. | Ferruginous seam, moderate reddish brown | | 0.1 |
| 4. | Chalk, partly weathered, very pale yellowish brown (10YR7/2) to grayish orange, relatively soft, moderately well laminated, splits easily parallel to bedding, slightly calcareous silty, speckled throughout. FOSSILS: Pseudoperna congesta, teleost scale | | 14.5 |
| 3. | Bentonite, very pale orange, in part stained dark yellowish orange by iron oxide; top and base of unit consist of limonite-stained gypsum. Actual bentonite seam is 3.3 cm thick | | 6.4 |
| 2. | Chalk, olive gray (5Y4/1), weathers light gray to medium yellowish brown (10YR5/2), relatively soft, in part laminated, splits easily along bedding, slightly calcareous silty, speckled throughout, weathers flaky. Bed of granular chalk, 3.7 cm thick, relatively hard, pale yellowish brown to very pale orange, speckled throughout, faintly burrow-mottled, lies 61 cm below top of unit. FOSSILS: limonitized inoceramid valves, Pseudoperna congesta, teleost bones and scales | 2 | 62.1 |
| 1. | Ferruginous seam, dark yellowish orange, jarositic | | 0.3 |
| Total thickness of measured section | 25 | 28.2 |
| LOCALITY 22--Gully in area of small badlands in SW Sec. 18, T. 15 S., R. 31 W., Gove County, Kansas. |
Thickness |
| m |
cm |
| SMOKY HILL CHALK MEMBER |
| 16. | Bentonite, light olive gray (5Y6/1), silty, with jarosite and much soft limonite in upper part of unit | | 2.1 |
| 15. | Chalk, weathered, very pale orange to dark yellowish orange, mostly soft, apparently laminated, splits easily along bedding, slightly calcareous silty, speckled throughout. Where most weathered unit forms brittle, lichen-splotched, resistant caprock; where least weathered forms shaly weathering slope. FOSSILS: Inoceramus (Platyceramus) platinus, Pseudoperna congesta, teleost bones and scales | 2 | 31.7 |
| 14. | Ferruginous gypsum seam, dark yellowish orange, probably a weathered bentonite seam | | 0.6 |
| 13. | Chalk, weathered, yellowish orange (10YR7/6) soft, apparently laminated throughout, splits easily along bedding, slightly calcareous silty, speckled throughout, weathers flaky. FOSSILS: teleost bones and scales | | 15.8 |
| 12. | Bentonite, very pale orange, lower part waxy and brittle, upper part consists of jarosite, coarsely crystalline selenite and chips of bentonite, actual bentonite seam 3.4 cm thick. Unit heavily mineralized, expands locally to 6.7 cm in thickness, forms resistant ledge on slopes and prominent reentrant on vertical faces | | 4.9 |
| 11. | Chalk, weathered, yellowish orange (10YR7/6) with very light gray streaks, soft to very soft, apparently more or less laminated throughout, calcareous silty, speckled throughout, weathers shaly, forms small pinnacles or gently rounded low slopes. Unit contains sparse limonite nodules that have rotten marcasite cores, in zone 1.28 m below top. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, teleost bones and scales | 2 | 74.4 |
| 10. | Ferruginous seam, very dark yellowish orange (10YR5/6), hard, platy, with very thin seam of coarsely crystalline selenite along center. Unit forms prominent bench, thickens locally to 4.6 cm | | 3.1 |
| 9. | Chalk, partly weathered, light olive gray (5Y5/2) to yellowish gray (5Y7/2), tough, well laminated near top, not obviously laminated through much of interval, slightly calcareous silty, speckled throughout, weathers flaky, forms smoothly rounded slopes. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, teleost scales | 1 | 46.5 |
| 8. | Chalk, medium olive gray (5Y5/1) to light olive gray (5Y5/2), very tough, mostly with somewhat granular appearance, not obviously laminated, splits rather unevenly along widely spaced planes, slightly calcareous silty, speckled throughout, possibly bioturbated in part. Steep faces spally, slopes weather flaky. Unit contains sparse limonite nodules with rotten marcasite cores in lower 1.52 m, common limonitized marcasite nodules in upper 1.68 m, and local polycuboidal pyrite nodules in upper 1.52 m. Uppermost 42.7 cm is conspicuous medium yellowish brown (10YR512) to pale yellowish brown, organic-rich bed, which is gradational with underlying chalk, slightly calcareous silty, not obviously laminated, much speckled, softer than underlying chalk, and weathers shaly. Unit contains shell-rich zone 67.0 cm thick, 1.71 m above base. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, Baculites sp. (smooth molds), teleost bones, coprolite | 5 | 97.5 |
| 7. | Bentonite, grayish yellow (5Y8/4), much limonite-stained locally, with seams of ferruginous gypsum at top and base. Actual bentonite seam 2.8 cm thick. Unit forms prominent bench. FOSSILS: Pseudoperna congesta | | 6.1 |
| 6. | Chalk, partly weathered, very pale yellowish brown (1 OYR 7 /2), silty, speckled with black grains (organic matter?). FOSSILS: Pseudoperna congesta | | 12.2 |
| 5. | Bentonite, light brown (5YR5/6). Unit consists mostly of coarsely crystalline selenite | | 0.6 |
| 4. | Chalk, partly weathered, light olive gray (5Y5/2), bioturbated, slightly calcareous silty, much speckled throughout. FOSSILS: I. (Platyceramus) platinus, burrow structures, teleost bones | | 13.1 |
| 3. | Bentonite, light brown (5YR5/6), silty. Unit consists mostly of coarsely crystalline selenite, with powdery gypsum at base | | 0.9 |
| 2. | Chalk, olive gray (5Y4/1), tough, bioturbated, slightly calcareous silty, speckled throughout, weathers shaly. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, teleost bones | | 42.7 |
| 1. | Bentonite, light brown (5YR5/6), silty. Unit composed mostly of limonite and gypsum | | 0.3 |
| Total thickness of measured section | 13 | 52.5 |
| LOCALITY 18--Bluff and adjacent erosional pinnacle directly south of Castle Rock, in SW Sec. 1, T. 14 S., R. 26 W., Gove County, Kansas. |
Thickness |
| m |
cm |
| SMOKY HILL CHALK MEMBER |
| 38. | Chalk, highly weathered, pale yellowish orange, soft, weathers shaly, gradational with overlying soil | | 21.4 |
| 37. | Bentonite, very dark yellowish orange (10YR5/6), somewhat silty, waxy | | 0.3 |
| 36. | Chalk, highly weathered, very pale orange to dark yellowish orange, fissile, apparently laminated, calcareous silty, much speckled throughout, weathers shaly | | 39.6 |
| 35. | Chalk, much weathered, grayish orange, apparently laminated, with poor to fair fissility, erodes to form smoothly curved cavernous surfaces, forms slopes, lichen-splotched. Rock contains numerous small solution vugs. Prominent gray line, parallel to bedding, 45.8 cm above base of unit. Limonite nodules occur in zone 9 cm thick, centered 45.8 cm above base. FOSSILS: Pseudoperna congesta, teleost scales and bones | | 91.4 |
| 34. | Bentonite, yellowish gray (5Y7/2), as thin film underlain by dark yellowish orange limonite | | 0.2 |
| 33. | Chalk, much weathered, pale yellowish orange, with traces of lamination, and fair fissility, calcareous silty, speckled throughout. Forms rounded, lichensplotched ledge. Paper-thin ferruginous seam lies 6.7 cm above base. FOSSILS: Inoceramus (Platyceramus) platinus, Pseudoperna congesta, teleost scales and bones | | 35.0 |
| 32. | Bentonite, dark yellowish orange, silty, marked by small limonite nodules | | 0.3 |
| 31. | Chalk, weathered, very pale yellowish brown (10YR7/2) to pale orange pink (5YR8/2), tough, resistant, cliff-forming, with traces of stratification, breaks with fair degree of fissility, lichen-splotched, calcareous silty, speckled, with sparse solution vugs. Very thin seam of limonite, less than 0.1 cm thick, lies 6.2 cm above base. Unit contains smooth, vertical joints, forms caprock. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, teleost bones and scales | 1 | 2.3 |
| 30. | Bentonite, moderate yellowish brown, hard, brittle, very silty, waxy. Upper 0.6 cm of unit consists of limonitic bentonite. Unit hosts small limonite nodules, forms part of reentrant at base of unit 31 | | 2.1 |
| 29. | Chalk, weathered, lower 1.56 m medium yellowish brown (10YR5/2) with local pale grayish orange (10YR8/4) horizontal banding, tough; upper 39.2 cm medium grayish orange (10YR6/4) and pale grayish orange (10YR8/4), lichen-splotched. Lower part apparently well laminated, with good fissility, weathers flaky. Upper part lacks obvious laminations, with good fissility, soft and punky, with unit 31 forms part of small vertical cliff. All rock calcareous silty, much speckled. Bed of limonite nodules, as much as 20 cm in diameter and 2.5 cm thick, lies 73 cm above base, marks very thin ferruginous seam. Second bed of limonite nodules, small, lies 52 cm below top of unit. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, teleost scales and bones | 1 | 95.2 |
| 28. | Chalk, partly weathered, light olive gray (5Y5/2), pale yellowish brown and very pale yellowish brown (10YR7/2), forms steep, cavernous slope. Unit not laminated in lowest 2.13 m, moderately well laminated in upper 34.2 cm. All rock is calcareous silty, speckled, has fair degree of fissility, weathers flaky. Middle part of unit weathers to lighter colors locally, and forms irregular, projecting ledges of hard, brittle yellow-colored chalk. Uppermost 27.5 m is distinctly darker colored than rest of unit, dark yellowish brown, probably organic rich, weathers distinctly shalier than rest of unit. Beds of small limonite nodules lie 48.8 cm and 80.5 cm below top, respectively. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, teleost bones and scales | 3 | 47.6 |
| 27. | Bentonite, yellowish gray, slightly silty, flaky, enclosed within lensing layers of limonite that include some jarosite and coarsely crystalline selenite. Where thickest, seam is bordered by crusts of crystalline selenite. Mineralized parts of unit form ledges on eroded slope. Where most mineralized the unit thickens to 6.1 cm | | 4.6 |
| 26. | Chalk, weathered, grayish orange to pale grayish orange (10YR8/4), soft, breaks blocky, burrowmottled, not conspicuously speckled. FOSSILS: Pseudoperna congesta, teleost bones and scales | | 9.2 |
| 25. | Bentonite, dark yellowish orange, as very thin film at top of unit consisting mostly of crystalline selenite | | 0.9 |
| 24. | Chalk, weathered, pale grayish orange to very pale yellowish brown, breaks blocky, burrow-mottled, not conspicuously speckled. FOSSILS: Pseudoperna congesta | | 10.7 |
| 23. | Bentonite, dark yellowish orange, slightly silty, brittle, in unit consisting predominantly of granular calcite | | 0.9 |
| 22. | Chalk, weathered, pale yellowish brown to grayish orange, tough, faintly bioturbated, calcareous silty, speckled throughout, forms pronounced, rounded shoulder on slope, weathers flaky, uppermost part weathers slabby. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta | | 29.0 |
| 21. | Bentonite, light brown (5YR5/6), silty, brittle, as minor component in seam consisting mainly of limonite and gypsum. Unit hosts sparse limonite nodules | | 0.6 |
| 20. | Chalk, partly weathered, medium olive gray (5Y5/1) to dark yellowish brown, surface dries to conspicuous light gray or very light gray. Rock very tough, somewhat granular, poorly stratified, more or less bioturbated, calcareous silty, speckled throughout. Unit forms smoothly convex, spally, buttressed slope where least weathered, lichen-coated cap rock where highly weathered. Where most weathered, unit has fair fissility. Conspicuous shelly zone, 1.7 m thick, with abundant I. (Platyceramus), lies 3.8 m above base of unit. Inoceramids and oysters common throughout unit. Dark line, 4 m above base of unit, marks position of small oblate spheroidal pyrite nodules. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, )Baculites sp. (smooth mold frags?), Stramentum haworthi, Zeugmatolepas sp., coprolite, teleost scales | 6 | 69.2 |
| 19. | Chalk and bentonite. Chalk medium olive gray (5Y5/1), very tough, not obviously laminated, bioturbated, shows some stratification, splits crudely parallel to bedding, calcareous silty, speckled throughout. Unit contains five subequally spaced bentonite seams occurring at base, 22.2 cm above base, 39.6 cm above base, 59.4 cm above base, and at top. Basal seam 0.6 cm thick, dark yellowish orange, consists solely of limonite and white, powdery gypsum; probably a weathered bentonite. Second seam is 0.6 cm thick, dark yellowish orange, brittle, silty, waxy, with associated powdery gypsum. Third seam is 0.3 cm thick, consists mostly of limonite and granular calcite. Fourth seam 1.5 cm thick, dark yellowish orange, brittle, silty, consists mostly of limonite and gypsum, hosts limonite nodules. Uppermost seam is 0.6 cm thick, medium olive gray (5Y5/1) to dark yellowish orange, brittle, silty, as very thin film in seam consisting mostly of limonite and some powdery gypsum. Uppermost seam hosts limonite nodules, thicker where most extensively mineralized. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, Inoceramus balticus?, Clioscaphites choteauensis, Baculites sp. (smooth molds) | | 82.3 |
| 18. | Chalk, medium olive gray (5Y5/1), very tough, not laminated, poorly fissile, weathers shaly, calcareous silty, speckled throughout, upper part bioturbated. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta | | 35.1 |
| 17. | Ferruginous/gypsiferous seam, light brown (5YR5/6) | | 0.2 |
| 16. | Chalk, olive gray (5Y4/1), dark yellowish brown to medium olive gray (5Y5/1) where partly weathered, very tough, lower 30 cm with poor fissility, upper part with fair fissility, no obvious laminations, calcareous silty, speckled throughout, weathers shaly, upper 9.2 cm bioturbated. Lower part of unit with abundant fossils, litters slope with shelly debris. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, Clioscaphites choteauensis, Inoceramus balticus, Baculites sp. (smooth molds) | | 76.2 |
| 15. | Bentonite, yellowish gray (5Y712), soft, waxy, slightly silty, 0.2 cm thick, in unit consisting mostly of limonite and gypsum, which overlie the bentonite seam | | 1.8 |
| 14. | Chalk, olive gray (5Y4/1), tough, not laminated, poorly fissile, in part bioturbated, calcareous silty, speckled throughout. Lighter-colored bed, 9.2 cm thick, bioturbated, lies 33.5 cm above base of unit, forms conspicuous band on eroded slope. Unit abundantly fossiliferous, slope littered with shelly debris. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta | | 77.7 |
| 13. | Bentonite, moderate yellowish brown (10YR5/2), silty, waxy, soft. Unit hosts sparse limonitized marcasite nodules as much as 70 cm in diameter and 9 cm thick | | 0.7 |
| 12. | Chalk, light olive gray (5Y6/1) to olive gray (5Y4/1), tough, not obviously laminated, fissile, calcareous silty, speckled throughout, in part stained by iron oxide, weathers shaly. Bed of limonite nodules lies 54.8 cm below top. Upper 30 cm richly fossiliferous, litters slope with shelly debris. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta | 1 | 17.5 |
| 11. | Bentonite, very dark yellowish orange. Unit consists mostly of white, powdery gypsum, which encloses a central seam composed mainly of limonite | | 1.2 |
| 10. | Chalk, light olive gray (5Y6/1) to medium olive gray (5Y5/1), tough, not obviously laminated, fissile, calcareous silty, much speckled throughout, weathers shaly. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, teleost vertebrae | | 36.6 |
| 9. | Bentonite, light brown (5YR5/6). Unit dominated by granular gypsum in fresh exposure, limonite in weathered exposure, thickens locally to 1.2 cm, locally hosts large limonite nodules | | 0.3 |
| 8. | Chalk, olive gray (5Y4/1) to medium olive gray (5Y5/1), very tough, obscurely laminated, poorly fissile, calcareous silty, much speckled throughout, weathers shaly. Prominent dark bed, 6 cm thick, probably organic rich, lies 1.7 m above base of unit. Some large inoceramids are partially surrounded by limonitized marcasite nodules. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, coprolite | 1 | 77.0 |
| 7. | Bentonite, dark yellowish orange, silty, brittle. Actual bentonite is 0.3 cm thick, lies in center of seam dominated by limonite and gypsum | | 0.9 |
| 6. | Chalk, olive gray (5Y 4/1), tough, not obviously laminated, moderately fissile, calcareous silty, much speckled throughout, weathers shaly. Some large inoceramids are partially surrounded by limonitized marcasite nodules. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, coprolite, teleost scales | 1 | 86.1 |
| 5. | Bentonite, pale grayish orange pink (5YR8/2), brittle, 0.6 cm thick, between seams of ferruginous gypsum | | 1.2 |
| 4. | Chalk, olive gray (5Y4/1) to light olive gray (5Y6/1), tough, poorly laminated, fissile, calcareous silty, much speckled throughout, weathers shaly. Seam of iron oxide, 0.2 cm thick, lies 56.4 cm below top of unit. Some inoceramid valves limonitized. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, coprolite, teleost bones | 2 | 1.2 |
| 3. | Bentonite, grayish orange, underlain by crystalline selenite. Large inoceramid valve partially surrounded by limonitized marcasite nodule. FOSSILS: I. (Platyceramus) platinus | | 0.3 |
| 2. | Chalk, dark olive gray (5Y3/1) to medium olive gray (5Y5/1), tough, obscurely laminated, fissile, calcareous silty, much speckled throughout, weathers shaly. Some inoceramid valves partially surrounded by large, limonitized marcasite nodules. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, coprolite, teleost bones | 1 | 28.2 |
| 1. | Bentonite, very light olive gray (5Y7/1), mostly stained dark yellowish orange, very silty, as seam approximately 0.1 cm thick, in unit consisting mostly of limonite and granular gypsum | | 1.2 |
| Total thickness of measured section | 26 | 86.2 |
| LOCALITY 19--Small badlands along southern tributary to Smoky Hill River, in NE, Sec. 2, T. 14 S., R. 26 W., Gove County, Kansas. |
Thickness |
| m |
cm |
| SMOKY HILL CHALK MEMBER |
| 28. | Bentonite, pale grayish orange pink (5YR8/2) or pinkish gray, bordered above and below by seams of limonite and gypsum, dark yellowish orange to moderate reddish brown | | 1.2 |
| 27. | Chalk, weathered, grayish orange, dark yellowish orange or very light gray, mostly soft, not obviously laminated to faintly laminated, good fissility, calcareous silty, speckled throughout. Paper-thin ferruginous seam lies 61.0 cm below top of unit. Bed 12.2 cm thick, tough, apparently burrow-mottled, lies 39.6 cm above base. Large inoceramids commonly surrounded in part by limonitized marcasite nodules. FOSSILS: Inoceramus (Platyceramus) platinus, Pseudoperna congesta, Clioscaphites vermiformis, acrothoracican borings, teleost bones and scales | 1 | 95.2 |
| 26. | Bentonite, dark yellowish orange to medium gray, very silty, somewhat brittle | | 0.3 |
| 25. | Chalk, medium olive gray (5Y5/1), mostly weathered light olive gray (5Y6/1) to pale grayish orange (10YR8/4) and dark yellowish orange, tough, weathers soft, not obviously laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, weathers flaky. Limonite nodules with rotten marcasite cores scattered throughout, concentrated in two zones 76.2 cm and 94.5 cm above base. Thin bed of brownish-colored chalk centers 10.7 cm below top of unit. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, Clioscaphites vermiformis, acrothoracican borings, Baculites sp. (smooth molds), teleost bones and scales, lignitized log | 1 | 30.0 |
| 24. | Bentonite, light olive gray (5Y6/1), very silty, soft, with associated limonite and medium crystalline selenite. Unit thickens locally to 1.5 cm where heavily mineralized | | 0.9 |
| 23. | Chalk, olive gray (5Y4/1) at base grading up to partly weathered chalk, dark yellowish brown to very pale yellowish brown (10YR7/Z), not obviously laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, weathers flaky. Unit bioturbated in bed 12.2 cm thick that lies 67.2 cm above base. Tough chalk, non-fissile, occurs in two beds, 6.1 cm and 12.2 cm thick, which lie 51.8 cm and 73.1 cm above base, respectively. Two very thin seams of iron oxide lie 30.5 cm and 49.8 cm below top. Large limonite nodules with rotten marcasite cores are scattered throughout unit, partially surround some large inoceramid valves. FOSSILS: I. (Platyceramus) platinus, Stramentum haworthi, Zeugmatolepas sp., Pseudoperna congesta, acrothoracican borings, teleost bones and scales | 1 | 49.6 |
| 22. | Bentonite?, grayish orange, in unit consisting mostly of powdery gypsum and minor amounts of light brown (10YR5/6) limonite. Unit hosts a few limonite nodules, as much as 61.0 cm in diameter and 6.1 cm thick, that have rotten marcasite cores. FOSSILS: Pseudoperna congesta | | 0.3 |
| 21. | Chalk, olive gray (5Y4/1), partly weathered to medium olive gray (5Y5/1) in upper 30 cm, tough, obscurely laminated, moderately fissile, calcareous silty, speckled throughout, weathers flaky. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta | 2 | 7.3 |
| 20. | Bentonite, dark yellowish orange, in seam consisting mostly of powdery gypsum with some limonite. Unit thickens to 3.1 cm where heavily mineralized. Unit hosts limonite nodules with rotten marcasite cores, and hard, smooth oblate spheroidal pyrite nodules | | 0.3 |
| 19. | Chalk, olive gray (5Y4/1) in lower part, grading upward to medium gray (5Y5/1) in uppermost part, tough where fresh, mostly obscurely laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, less calcareous and less speckled in lowest 1.52 m, weathers flaky. Bioturbated chalk, in bed 7.7 cm thick, lies 64.0 cm above base, forms weak bench covered with brittle chips of lighter-colored chalk. Lower 2.86 m characterized by small spheroidal pyrite nodules. Similar nodules scattered sparingly through remainder of unit. Limonitized marcasite nodules, partially enclosing valves of large inoceramids, scattered throughout unit. Some inoceramids partially to entirely lirnonitized. More prominent zones of nodules lie 91.3 cm, 1.74 m, 3.63 m, and 5.21 m above base unit. Limonite nodules are oblate spheroids, reach maximum dimensions of 67.0 cm in diameter and 9.2 cm thick. Paper-thin ferruginous seam lies 1.15 m above base. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, acrothoracican borings, teleost scales and bones | 7 | 50.0 |
| 18. | Bentonite, dark yellowish orange, in unit consisting mostly of limonite and gypsum. Unit hosts abundant marcasite nodules, most of which have been altered to limonite | | 0.6 |
| 17. | Chalk, olive gray (5Y4/1), tough where fresh, brittle where dry, laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, weathers flaky. Paper-thin ferruginous seam lies 1.38 m below top. Unit contains widely spaced limonite nodules. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, teleost scales | 2 | 86.5 |
| 16. | Bentonite, greenish gray, moderately silty, with numerous veinlets of jarosite | | 1.5 |
| 15. | Chalk, medium olive gray (5Y5/1) to olive gray (5Y4/1), tough, brittle where dry, well laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, spally on steep faces, weathers flaky. Paper-thin ferruginous seam, 22.9 cm above base, hosts small, flat limonite nodules. Unit bioturbated locally. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta | 1 | 25.5 |
| 14. | Ferruginous/gypsiferous seam, moderate yellowish brown (10YR5/2), soft | | 0.3 |
| 13. | Chalk, medium olive gray (5Y5/1), relatively soft, moderately well laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, weathers flaky, basal part waxy (bentonitic?) | | 12.5 |
| 12. | Bentonite, moderate yellowish brown (10YR5/2) to dark yellowish orange, extremely silty, in seam consisting mostly of gypsum and limonite. Actual bentonite approximately 0.2 cm thick | | 0.6 |
| 11. | Chalk, olive gray (5Y4/1), partly weathered to medium olive gray (5Y5/1), very tough where fresh, more brittle where partly weathered, obscurely laminated to not obviously laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, weathers flaky. Bioturbated chalk interval, 21 cm thick, forms light-colored weak bench on slopes, weathers to brittle chips, lies 42.8 cm above base of unit. Nodules of soft limonite partially enclose some large inoceramid valves in upper 30 cm of unit. FOSSILS: I. (Platyceramus) platinus, I. (Cladoceramus) undulatoplicatus, Pseudoperna congesta, teleost bones | 1 | 20.5 |
| 10. | Bentonite, moderate yellowish orange (10YR7/6), moderately silty, soft, waxy, with granular gypsum at base | | 0.9 |
| 9. | Chalk, olive gray (5Y4/1), tough, obscurely laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, weathers flaky. Basal few cm bioturbated. FOSSILS: I. (Cladoceramus) undulatoplicatus, Pseudoperna congesta, teleost bones and scales | | 83.9 |
| 8. | Ferruginous seam, dark yellowish orange and light brown (10YR5/6), consisting mostly of powdery limonite | | 0.1 |
| 7. | Chalk, olive gray (5Y 4/1) to medium olive gray (5Y5/1), tough, very brittle where dry, laminated to poorly laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, spally in steep faces, weathers flaky. Upper 21 cm with very thin bioturbated zones. Small polycuboidal pyrite nodules, subspherical, some partly limonitized, scattered through unit. FOSSILS: Pseudoperna congesta, teleost bones and scales | 1 | 34.2 |
| 6. | Bentonite, light olive gray (5Y6/1), very silty, with much coarsely crystalline selenite. Unit stained dark yellowish orange by iron oxide. Seam hosts abundant limonite nodules | | 0.6 |
| 5. | Chalk, medium olive gray (5Y5/1) to olive gray (5Y4/1), mostly laminated, splits easily parallel to bedding, calcareous silty, speckled throughout, weathers flaky. Bioturbated chalk, as very thin zone, lies 42.7 cm below top of unit, weathers to small brittle chips. Small, smooth to polycuboidal nodules of pyrite scattered throughout unit. FOSSILS: I. (Platyceramus) platinus, coprolite, teleost scales | 1 | 49.5 |
| 4. | Bentonite, light olive gray (5Y6/1), very silty, in seam consisting mostly of dark yellowish orange, limonitic, coarsely crystalline selenite. Unit hosts scattered limonite nodules | | 0.6 |
| 3. | Chalk, olive gray (5Y4/1), tough to brittle, obscurely to very well laminated, calcareous silty, speckled throughout, weathers soft and flaky. Bioturbated intervals very thin, lighter gray than rest of unit. weather to brittle chips, lie 39.6 cm and 1.1 m above base of unit. Polycuboidal nodules of pyrite occur in zones lying 61.0 cm and 1.25 m below top of unit. Some invertebrate shells partially limonitized. Unit contains scattered, oblate spheroidal limonite nodules. FOSSILS: I. (Platyceramus) platinus, Pseudoperna congesta, lignitized log, teleost bones | 2 | 28.6 |
| 2. | Bentonite, grayish orange to very pale orange, very silty, brittle, bordered above and below by soft seams of limonite/jarosite. Actual bentonite seam 0.6 to 0.9 cm thick | | 2.5 |
| 1. | Chalk, olive gray (5Y4/1) in lower 1.83 m, medium olive gray in upper part, very pale orange where weathered, tough, very well laminated throughout, splits easily parallel to bedding, calcareous silty, speckled throughout, weathers soft and flaky. Upper third of unit contains polycuboidal pyrite nodules and spherical limonite nodules with rotten marcasite cores. Paper-thin ferruginous seam lies 70 cm above base of unit. FOSSILS: I. (Cladoceramus) undulatoplicatus, Pseudoperna congesta | 3 | 30.8 |
| Total thickness of measured section | 29 | 14.8 |
| LOCALITY 13--Extensively eroded bluff and badlands on west side of small southern tributary to Smoky Hill River, in SE. Sec. 29, T. 15 S., R. 26 W., Gove County, Kansas. |
Thickness |
| m |
cm |
| SMOKY HILL CHALK MEMBER |
| 27. | Chalk, partly weathered, light olive gray (5Y6/1) to grayish orange and pale grayish orange (10YR8/4), soft, poorly laminated, splits easily along bedding, calcareous silty, speckled throughout, with oblate spheroidal, oxidized pyrite nodules, as much as 12 cm in diameter and 4.5 cm thick, in zone 39.6 cm above base. FOSSILS: Pseudoperna congesta, Baculites sp. (smooth molds), teleost bones and scales | 1 | 78.5 |
| 26. | Bentonite, olive gray (5Y4/1), brittle, waxy, silty | 1.2 |
| 25. | Chalk, lower 48.8 cm olive gray (5Y4/1), grading upward to weathered rock, grayish orange tinged with light olive gray (5Y6/1). Lower part of unit relatively soft, weathered part relatively harder; all rock poorly laminated, splits easily along bedding, calcareous silty, speckled throughout. Lower, darker chalk contains bed of lighter-colored chalk, 4.5 cm thick, weathers into brittle chips, forms minor ledge, 39.6 cm above base. Zone of small, oblate spheroidal pyrite nodules lies 91.5 cm above base. FOSSILS: Inoceramus (Platyceramus) platinus, I. ?(Cladoceramus) undulatoplicatus, Pseudoperna congesta, teleost scales | 1 | 37.3 |
| 24. | Ferruginous seam, light brown (5YR5/6) | | 0.1 |
| 23. | Chalk, medium olive gray (5Y5/1), soft, poorly laminated, calcareous silty, speckled throughout, weathers flaky | | 13.7 |
| 22. | Bentonite, light brown (5YR5/6), silty, with much associated iron oxide | | 0.3 |
| 21. | Chalk, weathered, grayish orange to moderate yellowish brown (10YR5/2), soft, poorly laminated, calcareous silty, speckled throughout. Bed of tough chalk, 51.8 cm thick, pale yellowish brown, 9.1 cm above base of unit, forms prominent bench, weathers into brittle chips. FOSSILS: I. (Cladoceramus) undulatoplicatus, Pteria sp. B, Lucina sp. A, Baculites sp. (smooth molds), I. (Platyceramus) platinus, Pseudoperna congesta, Clioscaphites sp. (mold fragment), teleost scales | 1 | 8.3 |
| 20. | Bentonite, medium gray, mostly weathered light brown (5YR5/6), with much associated limonite | | 0.6 |
| 19. | Chalk, weathered, dark grayish orange (10YR6/4), with iron oxide stains, relatively hard, poorly laminated, splits easily along bedding, calcareous silty, much speckled throughout, weathers flaky. FOSSILS: juvenile I. (Platyceramus) platinus | 1 | 17.5 |
| 18. | Chalk, partly weathered, light gray to grayish orange, tough, nonlaminated, bioturbated, calcareous silty, speckled throughout, forms prominent bench, weathers into brittle chips. Layer of small spheroidal pyrite nodules lies at center of unit. Lower half with scattered nodules of limonite/jarosite/marcasite. FOSSILS: I. (Cladoceramus) undulatoplicatus, Baculites sp. (smooth molds) | | 36.6 |
| 17. | Chalk, olive gray (5Y4/1) to medium yellowish brown (10YR5/2), relatively soft, nonlaminated, calcareous silty, faintly speckled, weathers flaky. Ferruginous seam, 0.2 cm thick, lies 1.46 m above base. FOSSILS: Inoceramus fragments, Pseudoperna congesta, Baculites sp. (smooth mold) | 2 | 68.3 |
| 16. | Bentonite, medium light gray, stained dark yellowish orange by iron oxide, with associated selenite crystals | | 0.6 |
| 15. | Chalk, olive gray (5Y4/1) in lower part, grading upward to partly weathered rock, dark yellowish brown and light olive gray (5Y5/2), soft, not obviously laminated, splits parallel to bedding, calcareous silty, speckled throughout, weathers flaky, with small nodules of oxidized pyrite scattered on slope and sparse oblate spheroidal limonite nodules with marcasite cores in zone at middle of unit. FOSSILS: I. (Platyceramus) platinus, Inoceramus stantoni?, Pseudoperna congesta, ammonite mold fragment, Baculites sp. (smooth molds), teleost remains | 3 | 4.5 |
| 14. | Bentonite, pale yellowish brown, stained dark yellowish orange by iron oxide, underlain locally by gypsum. Unit hosts scattered oblate spheroidal limonite nodules with marcasite cores, as much as 18.3 cm in diameter and 6.1 cm thick | | 1.2 |
| 13. | Chalk, partly weathered, light olive gray (5Y5/2) to moderate yellowish brown (10YR5/2), in part very well laminated, splits parallel to bedding, calcareous silty, speckled throughout, weathers flaky. Zone 45.8 cm thick, lying 45.8 cm below top of unit, is olive gray (5Y3/2). Uppermost 45.8 cm is weathered, grayish orange. Zone 12 cm thick, lying 1.28 m below top of unit, is olive gray (5Y4/1), more clayey and less well speckled than remainder of unit. Ferruginous seam, 0.2 cm thick, lies 36.6 cm above base. Spheroidal pyrite nodules, as much as 3 cm in diameter, are scattered through unit and are especially common in zone 61 cm thick and lying 61 cm below top of unit. Oblate spheroidal limonite nodules partially enclose large inoceramid valves near base of unit. FOSSILS: I. (Cladoceramus) undulatoplicatus, Pseudoperna congesta, Baculites sp. (smooth mold), I. (Volviceramus) grandis (highest level for species), Durania maxima | 2 | 95.7 |
| 12. | Ferruginous seam, moderate yellowish brown (10YR5/2) | | 0.2 |
| 11. | Chalk, medium olive gray (5Y4/2), relatively soft, moderately well laminated, splits along bedding, calcareous silty, speckled throughout, weathers flaky. Harder chalk, weathers light gray, bioturbated, weathers into small brittle chips, in two very thin zones lying 53.4 cm and 76.1 cm above base. Small pyrite nodules, polycuboidal type, widely scattered in unit. FOSSILS: I. (Volviceramus) grandis, I. (Platyceramus) cycloides, I. (Platyceramus) platinus, Pseudoperna congesta, teleost bones, flattened carbonized log | 2 | 68.3 |
| 10. | Ferruginous/gypsiferous seam, moderate yellowish brown, hosts nodules of limonite/jarosite/marcasite, as much as 30.5 cm in diameter and 10.7 cm thick, partially enclose large inoceramid valves. FOSSILS: I. (Volviceramus) grandis, Pseudoperna congesta | | 0.3 |
| 9. | Chalk, medium olive gray (5Y5/1), relatively soft, poorly laminated, calcareous silty, speckled throughout, weathers flaky. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta, teleost bones | 2 | 22.5 |
| 8. | Ferruginous/gypsiferous seam, moderate yellowish brown (10YR512) | | 0.2 |
| 7. | Chalk, partly weathered, moderate yellowish brown (10YR5/2), relatively soft, laminated, calcareous silty, speckled throughout, weathers flaky. FOSSILS: I. (Volviceramus) grandis, Pseudoperna congesta | | 22.9 |
| 6. | Ferruginous/gypsiferous seam, moderate yellowish brown (10YR5/2), hosts large limonite/jarosite/marcasite nodules | | 0.3 |
| 5. | Chalk, olive gray (5Y4/1), relatively tough, upper portion partly weathered, light olive gray (5Y5/2), softer. Unit well laminated, splits easily along bedding, spalls in large blocks on steep faces, weathers flaky, calcareous silty, speckled throughout. Ferruginous/gypsiferous seam, 0.3 cm thick, dark yellowish orange, lies 1.51 m below top. Unit contains scattered hemispherical to spheroidal pyrite nodules. Some inoceramid valves pyritized or limonitized. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta, Durania maxima, teleost bones | 4 | 42.1 |
| 4. | Bentonite, medium gray, mostly weathered dark yellowish orange | | 0.6 |
| 3. | Chalk, dark olive gray (5Y3/1), very tough, very well laminated, splits easily along bedding, calcareous silty, much speckled throughout, spally on steep faces, weathers flaky. Bioturbated chalk, in zone 13.7 cm thick, lies 41.2 cm above base. Ferruginous seams, dark yellowish orange, 0.3 cm or less in thickness, lie 53.4 cm and 1.51 m below top of unit. Some inoceramid valves are limonitized. FOSSILS: I. (Volviceramus) grandis, Pseudoperna congesta | 2 | 95.7 |
| 2. | Bentonite, light brown (5YR5/6) to moderate yellowish brown (10YR5/2), associated with small selenite crystals and local, very small nodules of limonite/gypsum | | 0.6 |
| 1. | Chalk, dark olive gray (5Y3/1), relatively soft, mostly very well laminated, splits easily along bedding, calcareous silty, much speckled throughout, spally on steep faces, weathers flaky. Uppermost 30.5 cm pale yellowish brown, bioturbated, tough, speckled, forms small bench, weathers into brittle chips. FOSSILS: I. (Volviceramus) grandis, Pseudoperna congesta | 1 | 83.3 |
| Total thickness of measured section | 29 | 1.4 |
| LOCALITY 12--Extensively eroded bluff on west side of small southern tributary to Smoky Hill River, in SW Sec. 16, T. 15 S. , R. 26 W., Gove County, Kansas. |
Thickness |
| m |
cm |
| SMOKY HILL CHALK MEMBER |
| 24. | Ferruginous seam, moderate yellowish brown | | 0.2 |
| 23. | Chalk, partly weathered at base, light olive gray (5Y5/2, 5Y6/1), grading upward to weathered chalk, grayish orange, relatively soft, laminated, fissile, calcareous silty, speckled throughout, weathers shaly. Paper-thin ferruginous seam lies 36.6 cm below top of unit. FOSSILS: Inoceramus (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta, Squalicorax falcatus | 2 | 83.5 |
| 22. | Bentonite, dark yellowish orange, associated with granular gypsum, hosts limonite/jarosite nodules | | 1.2 |
| 21. | Chalk, partly weathered, light olive gray (5Y5/2, 5Y6/1), relatively soft, laminated, splits easily along bedding, calcareous silty, speckled throughout, weathers flaky. FOSSILS: I. (Volviceramus) grandis, Pseudoperna congesta | | 51.8 |
| 20. | Ferruginous seam, limonitic and jarositic | | 0.2 |
| 19. | Chalk, partly weathered, light olive gray (5YS/2, 5Y6/1), relatively soft, laminated, splits easily along bedding, calcareous silty, speckled throughout, weathers flaky. Layer of small polycuboidal pyrite nodules lies 99.0 cm above base. Limonite/marcasite nodules, some partially enclosing inoceramid valves, common in zone near middle of unit. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta, Durania maxima (float) | 1 | 57.2 |
| 18. | Ferruginous/gypsiferous seam, moderate yellowish brown (10YR5/2) | | 0.3 |
| 17. | Chalk, partly weathered, light olive gray (5Y5/2), tough; more or less well laminated, splits easily along bedding, calcareous silty, speckled throughout, weathers flaky. Basal 6.1 to 7.7 cm yellowish gray (5Y7/2), thinly laminated, with unit 15 forms conspicuous light-colored band on eroded slope. Zone of bioturbated chalk, light gray, 12.2 cm thick, calcareous silty, almost nonspeckled, lies 30.5 cm above base. Limonite nodules common in lower 46 cm of unit. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta, Stramentum haworthi, teleost bones | 1 | 25.5 |
| 16. | Ferruginous/gypsiferous seam, moderate yellowish brown (10YR5/2) | | 0.3 |
| 15. | Chalk, light gray, tough, laminated, with discrete burrow structures, calcareous silty, faintly speckled, with unit 17 forms conspicuous light-colored band on eroded slope. FOSSILS: I. (Volviceramus) grandis, Pseudoperna congesta | | 27.5 |
| 14. | Chalk, partly weathered, moderate yellowish brown (10YR512) to dark yellowish brown, partly light olive gray (5Y6/1) in lower portion of unit, relatively hard, in part well laminated, calcareous silty, more or less highly speckled throughout, weathers flaky. Ferruginous/gypsiferous seam, moderate yellowish brown, 0.3 cm thick, with associated spheroidal limonitic pyrite nodules as much as 12.2 cm in diameter, lies 41.2 cm above base of unit. Zone of hard chalk, probably bioturbated, dark yellowish brown, 9.1 cm thick, lies 1.27 m above base of unit. Layer of limonitic marcasite concretions lies 77.5 cm below top of unit. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Durania maxima (float), Pseudoperna congesta, Zeugmatolepas sp. | 2 | 34.7 |
| 13. | Chalk, light gray, relatively hard, bioturbated, forms conspicuous white band on slope | | 12.2 |
| 12. | Ferruginous/gypsiferous seam, moderate yellowish brown (10YR5/2) | | 0.3 |
| 11. | Chalk, partly weathered, moderate yellowish brown (10YR5/2) to dark yellowish brown, relatively soft, not obviously laminated, less speckled than subjacent chalk, forms distinctive brown band on eroded slope. Sparse oblate spheroidal limonite concretions occur in upper part of unit. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta | 1 | 19.4 |
| 10. | Ferruginous/gypsiferous seam, light brown (5YR5/6). Hosts oblate spheroidal limonite/jarosite nodules as much as 20 cm in diameter and 9.2 cm thick | | 0.3 |
| 9. | Chalk, partly weathered, medium olive gray (5Y5/l) to light olive gray (5Y512, 5Y6/1), soft, more or less laminated, splits easily along bedding, calcareous silty, speckled throughout, weathers flaky. Layer of limonite nodules lies 79.3 cm above base of unit. FOSSILS: I. (Volviceramus) grandis, Pseudoperna congesta, teleost remains, Squalicorax falcatus | 1 | 25.1 |
| 8. | Ferruginous/gypsiferous seam, dark yellowish orange | | 0.2 |
| 7. | Chalk, partly weathered, medium olive gray (5Y5/1) to moderate yellowish brown (10YR5/2), moderately hard, more or less laminated throughout, calcareous silty, speckled throughout, weathers flaky. FOSSILS: I. (Volviceramus) grandis, Pseudoperna congesta, Durania maxima (1.6 km to east) | 1 | 37.3 |
| 6. | Ferruginous/gypsiferous seam, moderate yellowish brown (10YR5/2) | | 0.3 |
| 5. | Chalk, partly weathered, light gray to grayish brown and light olive gray, tough, more or less burrowmottled throughout, calcareous silty, speckled throughout. Basal 12.2 cm harder, much bioturbated, forms light gray band on slope. Uppermost 15.3 cm nonbioturbated, laminated. Unit weathers flaky. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta | | 61.0 |
| 4. | Ferruginous/gypsiferous seam, dark yellowish orange, hosts oblate spheroidal limonite/jarosite nodules as much as 30.5 cm in diameter and 7.3 cm thick | | 0.3 |
| 3. | Chalk, partly weathered, medium olive gray (5Y5/1) to light olive gray (5Y6/1), relatively soft, mostly obscurely laminated, calcareous silty, speckled throughout, weathers flaky. Unit contains scattered pods of bioturbated chalk, light olive gray (5Y6/1), weathers to form large, brittle chips. Basal 15.3 cm is tough, bioturbated chalk, light olive gray (5Y6/1), weathers into small brittle chips, conspicuous on eroded slope. Paper-thin ferruginous seam lies 45.7 cm above base of unit. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta | 2 | 43.9 |
| 2. | Bentonite, dark yellowish orange, associated with gypsum, hosts limonite/jarosite/marcasite nodules as much as 30.5 cm in diameter and 9.2 cm thick | | 0.6 |
| 1. | Chalk, olive gray (5Y4/1), tough, laminated, calcareous silty, speckled throughout, weathers flaky. Unit contains several thin zones of harder, bioturbated chalk, light olive gray (5Y611), weathers to form small brittle chips, form light-colored bands on eroded slope. Paper-thin ferruginous seam lies 82.3 cm above base. Limonitized marcasite nodule, oblate spheroidal, 42.7 cm in diameter and 9.1 cm thick, lies 1.6 m above base of unit. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta | 3 | 11.0 |
| Total thickness of measured section | 18 | 94.3 |
| LOCALITY 17--Badlands and bluffs on west side of Hackberry Creek, in SW Sec. 16, T. 14 S., R. 25 W., Trego County, Kansas. |
Thickness |
| m |
cm |
| SMOKY HILL CHALK MEMBER |
| 12. | Chalky limestone, weathered, grayish orange, relatively hard, brittle, bioturbated, forms conspicuous, flat-topped bench. FOSSILS: Inoceramus (Platyceramus) platinus, Pseudoperna congesta | | 9.1 |
| 11. | Bentonite, light brown (5YR5/6), ferruginous | | 0.3 |
| 10. | Chalk, weathered, grayish orange with streaks of yellowish gray (5Y7/2), soft, laminated, very well laminated in uppermost 15.3 cm, splits easily along bedding, calcareous silty, speckled throughout. Limonite nodules, widely spaced, occur in zones lying 61.0 cm, 76.3 cm, and 1.28 m below top of unit. Unit eroded locally so as to form steep face with three prominent ledges. FOSSILS: I. (Volviceramus) grandis, Pseudoperna congesta | 2 | 16.5 |
| 9. | Chalk, weathered, grayish orange, relatively soft, more or less well laminated throughout, calcareous silty, much speckled throughout, weathers shaly. Chalky limestone bed, grayish orange, relatively hard, brittle, 10.5 cm thick, bioturbated, ledgeforming, lies 42.7 cm above base of unit. Uppermost 18 cm of unit also harder than main body of unit, laminated, forms minor bench. Ferruginous seams, central one bentonite?, each less than 0.4 cm thick, lie 42.7 cm, 97.5 cm, and 1.83 m above base of unit. FOSSILS: I. (Volviceramus) grandis, Pseudoperna congesta | 2 | 22.6 |
| 8. | Chalk, weathered, grayish orange, relatively soft, well laminated, splits easily along bedding, calcareous silty, speckled throughout, weathers shaly, forms cavernous slope. Unit contains two prominent beds of chalky limestone, pale grayish orange (10YR8/4), bioturbated, ledge-forming. Lower bed is 18.3 cm thick and lies 1.30 cm above base of unit; upper bed is 15.2 cm thick, lies at top of unit, weathers into irregular slabs, forms prominent, flattopped bench. Chalky limestones locally coated with lichens. Paper-thin ferruginous seams, light brown (5YR5/6), each less than 0.1 cm thick, lie 61.0 cm and 97.5 cm above base. Upper seam hosts small limonitized marcasite nodules. FOSSILS: I. (Volviceramus) grandis, Pseudoperna congesta | 2 | 28.7 |
| 7. | Chalk and chalky limestone, weathered. Chalk is grayish orange to dusky yellow, relatively soft, more or less laminated, calcareous silty, speckled throughout, forms reentrants on steep faces, gradational with harder beds, weathers shaly. Chalky limestone is grayish orange to very pale orange, relatively hard, brittle, bioturbated, with sparse speckling. Uppermost hard bed lichen-splotched locally. Unit rich in inoceramid debris. Limonitized marcasite nodules, as large as 61.0 cm in diameter and 6.2 cm thick, lie in layers 73 cm and 1.19 m above base. FOSSILS: I. (Volviceramus) grandis, Pseudoperna congesta, I. (Platyceramus) platinus, Durania maxima, isolated lepadomorph cirriped plates, acrothoracican borings, Portheus, Ptychodus | 2 | 89.6 |
| 6. | Chalk, partly weathered, olive gray (5Y3/2) to light olive gray (5Y5/2), relatively soft, obscurely laminated, uppermost part bioturbated, calcareous silty, speckled throughout, weathers flaky. Layers of limonitized marcasite nodules lie at base and 58.0 cm above base of unit. Unit rich in inoceramid debris. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta, Stramentum haworthi, Zeugmatolepas sp., acrothoracican borings, Durania maxima, teleost bones, lignitized log with Teredolithus | 1 | 61.7 |
| 5. | Chalk, olive gray (5Y4/1), in part weathered light olive gray (5Y5/2), tough, brittle, mostly welllaminated, calcareous silty, speckled throughout, weathers flaky. Bioturbated chalk, in thin zones, especially 1.8 m above base, form light-colored bands on eroded slope, weather into small brittle chips. Ferruginous/gypsiferous seams, light brown (5YR5/6), each less than 0.2 cm thick, lie 6.88, 7.48, and 8.1 m above base. First and third seams host limonitized marcasite nodules as much as 45.7 cm thick and 9.1 cm thick. Granular gypsum seams, each less than 0.2 cm thick, lie 1.75 m above base and 88.5 cm below top of unit. Lower of these seams hosts limonitized marcasite nodules. Unit contains scattered limonitized marcasite nodules not associated with mineralized weathered bentonite? seams. Unit contains interval rich in inoceramid debris, approximately 60 cm thick, lying 6.08 m above base. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta, acrothoracican borings | 8 | 88.7 |
| 4. | Bentonite, moderate yellowish brown (10YR5/2), very silty | | 0.3 |
| 3. | Chalk, olive gray (5Y4/1), light olive gray (5Y6/1), and medium light gray, relatively hard, softer where weathered, well laminated, splits evenly along bedding, slightly calcareous silty, speckled throughout, with conspicuous smooth vertical joints, weathers flaky. Bed of harder chalk, light gray, 21.4 cm thick, lies 24.4 cm above base, forms smoothly rounded shoulder on weathered surfaces. Ferruginous/gypsiferous seam, less than 0.2 cm thick, lies on top of harder bed. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta, teleost scales | 1 | 0.8 |
| 2. | Bentonite, very pale orange to dark yellowish orange. Unit thickens locally to 4.9 cm by addition of ferruginous/gypsiferous seams at top and base. Unit locally hosts limonite nodules with rotten marcasite cores. Unit forms conspicuous reentrant on steep faces | | 2.5 |
| 1. | Chalk, medium olive gray (5Y5/1) to olive gray (5Y4/1), grades upward to light olive gray (5Y6/1), tough, obscurely laminated, splits irregularly along bedding, slightly calcareous silty, speckled throughout, weathers flaky. Bed of bioturbated chalk, 20 cm thick, lying 21.3 cm below top of unit, granular, contains very small limonite nodules near base, forms light-colored band on weathered exposure, forms minor shoulder on eroded slope. Ferruginous/gypsiferous seam, less than 0.2 cm thick, lies on top of bioturbated chalk. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta, teleost bones and scales | 1 | 98.3 |
| Total thickness of measured section | 23 | 19.1 |
| LOCALITY 1--Bluffs and badlands along western side of Hackberry Creek, in west half Sec. 24 and NW Sec. 25, T. 14 S., R. 25 W., Trego County, Kansas. |
Thickness |
| m |
cm |
| SMOKY HILL CHALK MEMBER |
| 61. | Chalk, weathered, very pale orange to yellowish gray (5Y8/1) to nearly white, mostly brittle and relatively resistant. Bed of softer chalk, 13.8 cm thick, splits easily along bedding, 58 cm above base. Unit in part well laminated, with thin bioturbated zone shortly above middle. Limonite nodules occur sparingly in zone 46 cm below top. Basal 49 cm forms resistant ledge. Bentonite seam, 0.6 cm thick, light brown (5YR5/6), lies in center of soft chalk bed, 97.5 cm below top of unit. Ferruginous seam, 0.3 cm thick, lies 26 cm above base of unit. FOSSILS: Inoceramus (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta, acrothoracican borings, teleost scales | 1 | 80.0 |
| 60. | Chalk, weathered, grayish orange, soft, forms conspicuous reentrant on steep faces, weathers shaly, with bentonite seam, 2.1 cm thick, pale yellowish green, limonitic, 18.3 cm above base. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta, teleost scales | | 48.8 |
| 59. | Chalk, weathered, very pale orange, grayish orange or dark yellowish orange, in part relatively hard and moderately resistant, in part softer and weathering shaly. Central bed of more resistant chalk, 30 cm thick, well laminated. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta, teleost scales | 1 | 6.9 |
| 58. | Chalk, olive gray (5Y 4/1), partially weathered to light olive gray (5Y5/2), grading upward to weathered chalk, dark yellowish brown, grayish orange and dark yellowish orange (at top); relatively soft, splits easily along bedding, slightly calcareous silty, speckled throughout, weathers shaly. Bentonite seam, 1.5 mm thick, dark yellowish orange, at base of highly gypsiferous interval 4.6 cm thick, lies 1. 71 m above base. Second bentonite seam, 1.5 mm thick, dark yellowish orange, selenitic, lies 2.68 m above base of unit. Unit contains a few limonitic nodules lying about 2.44 m below top. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta, acrothoracican borings, sponge? borings, teleost bones | 5 | 82.3 |
| 57. | Chalk, pale yellowish gray (5Y812), pale yellowish orange, and grayish orange, relatively soft, splits easily along bedding, calcareous silty, speckled throughout, weathers shaly. Lowermost and uppermost few cm are slightly harder, sparsely bioturbated, form slightly projecting ledges on weathered slope. FOSSILS: I. (Volviceramus) grandis, I. (Platyceramus) platinus, Pseudoperna congesta | | 70.1 |
| 56. | Chalk, weathered, pale grayish orange to grayish orange, relatively hard, gradational with adjacent units, bioturbated, calcareous silty, forms projecting ledge on eroded slope. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta | | 18.3 |
| 55. | Chalk, olive gray (5Y4/1), in part weathered to grayish yellow or pale yellowish orange, relatively soft, splits easily along bedding, calcareous silty, speckled throughout, weathers crumbly. Three intervals of chalk, weathered, pale grayish to grayish orange, 9.2, 30.5, and 45.5 cm thick, lying 27.4 cm, 1.22 m, and 2.35 m above base, respectively, are harder, more massive in appearance, laminated, form conspicuous ledges on eroded slope. Large oblate spheroidal nodules of limonite, with rotten marcasite cores, scattered through unit, some partially enclosing large inoceramid valves, are especially common just above middle of unit. Both hard and soft chalks contain burrow structures locally. Eroded slope of unit is littered with skeletal debris, much of which is derived from upper half of interval. FOSSILS: I. (Platyceramus) platinus, I. (Volviceramus) grandis, Pseudoperna congesta, acrothoracican borings, Durania maxima (float) | 3 | 90.2 |
| 54. | Chalky limestone, weathered, medium light gray near base, yellowish gray (5Y7/2) to pale yellowish gray (5Y8/2) above, relatively hard, brittle, resistant, forms conspicuous low bench. FOSSILS: I. (Volviceramus) grandis, Pseudoperna congesta, I. (Platyceramus) platinus? | | 58.0 |
| 53. | Bentonite, dark yellowish orange, paper-thin, in seam consisting mostly of powdery gypsum | | 0.6 |
| 52. | Chalk, partly weathered, dark yellowish brown to light olive gray (5Y6/1), relatively soft, obscurely laminated, splits easily along bedding, slightly calcareous silty, sparingly speckled. FOSSILS: I. (Volviceramus) grandis, Pseudoperna congesta, I. (Platyceramus) platinus? | | 12.6 |
| 51. | Bentonite, dark yellowish orange, slightly silty. Upper part of unit is selenitic | | 1.8 |
| 50. | Chalk, weathered, grayish orange, relatively soft | | 5.2 |
| 49. | Bentonite, dark yellowish orange, as paper-thin seam at top of unit consisting mostly of powdery gypsum | | 1.5 |
| 48. | Chalk, weathered, olive gray (5Y4/1), in part weathered grayish yellow to grayish orange, relatively soft, bioturbated, weathers shaly. Bed of harder chalk, 9.1 cm thick, brittle, lies 45.7 cm above base, forms projecting ledge on eroded slope. Unit contains partially limonitized, nearly spherical pyrite nodules near top. FOSSILS: I. (Volviceramus) grandis, I. (Platyceramus) platinus?, Pseudoperna congesta | | 73.1 |
| 47. | Chalk, partly weathered, pale olive gray (5Y7/1) to yellowish gray (5Y7/2, 5Y8/1), nonresistant, splits easily along bedding, slightly calcareous silty, speckled throughout, weathers shaly. Basal 39.6 cm is more massive, bioturbated. Zone 12.2 cm thick, bioturbated, lies 39.6 cm above base of unit. Uppermost 9.0 cm also bioturbated. FOSSILS: Inoceramus sp. (fragments). | | 88.3 |
| Measured thickness of Smoky Hill Chalk Member | 16 | 37.7 |
| FORT HAYS LIMESTONE MEMBER |
| 46. | Chalky limestone, weathered, pale yellowish gray (5Y8/2) to light olive gray (5Y6/1), dries nearly white, relatively hard, brittle, resistant, thoroughly bioturbated, forms conspicuous platform across sizeable area of exposure. FOSSILS: Inoceramus (Volviceramus) koeneni, Pseudoperna congesta, Bullopora sp. | | 79.2 |
| 45. | Bentonite, olive gray (5Y4/1), selenitic, with abundant black specks (biotite?), forms prominent reentrant | | 0.9 |
| 44. | Chalky limestone, weathered, yellowish gray (5Y7/2) to pale yellowish gray (5Y8/2), dries nearly white, relatively hard, brittle, bioturbated throughout, forms part of vertical cliff | | 30.5 |
| 43. | Chalk, olive gray (5Y4/1), weathered partly to light olive gray (5Y6/1), relatively soft, thoroughly bioturbated, forms small reentrant on cliff face. FOSSILS: Inoceramus sp. (fragments) | | 15.3 |
| 42. | Bentonite, light olive gray, stained grayish orange by limonite | | 2.2 |
| 41. | Chalky limestone, partly weathered, light gray to light olive gray (5Y5/2, 5Y5/1), weathers pale yellowish gray (5Y812) to nearly white or pale grayish orange (10YR7/4), relatively hard, brittle, bioturbated throughout, forms major ledge in face of cliff exposure. Shaly weathering interval, medium olive gray (5Y5/1) where least weathered, at center of bed, forms small reentrant on cliff face. FOSSILS: Inoceramus sp. (fragments), Pseudoperna congesta | 1 | 31.2 |
| 40. | Bentonite?, light olive gray (5Y5/2), shaly, streaked with chalk, speckled by black grains (biotite?) | | 1.5 |
| 39. | Chalky limestone, weathered, yellowish gray (5Y8/1), pale grayish orange (10YR8/4) to nearly white, locally stained dark yellowish orange, nearly all bioturbated, lichen-splotched, relatively hard, brittle, forms part of cliff face. Unit is divided into three parts by subequally spaced bedding planes. Faint laminations occur adjacent to lower bedding plane. FOSSILS: Inoceramus sp. (fragments), Pseudoperna congesta | 1 | 46.4 |
| 38. | Chalk, partly weathered, pale yellowish brown to light olive gray (5Y6/1), in part weathered to grayish orange, relatively soft, in part bioturbated, forms prominent reentrant on cliff face, weathers shaly. Bentonite seam, light olive gray (5Y5/2), lies 1.5 cm above base. Unit contains sparse, small limonite nodules | | 13.8 |
| 37. | Chalky limestone, weathered, pale yellowish gray (5Y8/2), pale grayish orange (10YR8/4) to nearly white, relatively hard, brittle, bioturbated especially in lower half and near top, forms part of steep cliff face. FOSSILS: Inoceramus sp. (bowl-shaped lower valve), Pseudoperna congesta | | 89.9 |
| 36. | Shale, light olive gray (5Y5/2) bentonitic?, with sparse black specks (biotite?), forms prominent reentrant on cliff face. | | 4.0 |
| 35. | Chalky limestone, weathered, pale yellowish gray (5Y8/2) to pale grayish orange (10YR8/4), relatively hard, brittle, bioturbated throughout, locally lichensplotched, forms ledge of cliff face. Unit contains sparse, small pyrite nodules. Soft chalk, argillaceous, shaly, in very thin unit lying 9.2 cm above base, forms minor reentrant on vertical face. FOSSILS: Inoceramus sp. (coarsely ribbed fragments) | | 45.7 |
| 34. | Chalk, light olive gray (5Y512), argillaceous, bentonitic?, bioturbated, with lenticular chalk-filled burrows. Unit forms reentrant on cliff face | | 2.5 |
| 33. | Chalky limestone, weathered, pale yellowish gray (5Y812) to pale grayish orange (10YR8/4), relatively hard, brittle, bioturbated throughout, lichens-plotched, forms part of steep cliff face. FOSSILS: Inoceramus sp. (bowl-shaped lower valve) | | 30.5 |
| 32. | Chalk, light olive gray (5Y512), argillaceous, bentonitic?, highly bioturbated, with chalk-filled burrows, weathers shaly. Unit forms reentrant on cliff face | | 3.1 |
| 31. | Chalky limestone, weathered, pale yellowish gray (5Y8/2) mottled with light gray, relatively hard, brittle, bioturbated throughout, lichen splotched, forms part of steep cliff face. Prominent bedding plane lies 15.3 cm below top | | 73.0 |
| 30. | Chalk, weathered, yellowish gray (5Y7/2), dries yellowish gray (5Y8/1) to nearly white, top and base slightly darker and shalier than rest of unit, bioturbated, uppermost part with nearly white chalk-filled burrows, forms reentrant on cliff face, weathers shaly. FOSSILS: Inoceramus sp. (bowl-shaped lower valve), Pseudoperna congesta | | 13.8 |
| 29. | Chalky limestone, weathered, pale yellowish gray (5Y8/2), dries nearly white, relatively hard, brittle, bioturbated, forms small projecting ledge in midst of shalier interval. Unit contains scattered small limonite nodules. FOSSILS: Inoceramus cf. I. (Cremnoceramus) browni, Pseudoperna congesta | | 15.3 |
| 28. | Chalk, partly weathered, light olive gray (5Y5/2), bentonitic?, relatively soft, in part laminated, in part bioturbated, with nearly white chalk-filled burrows in upper part. Unit forms reentrant on cliff face, weathers shaly | | 6.1 |
| 27. | Bentonite, light olive gray (5Y6/1), biotitic | | 1.5 |
| 26. | Chalky limestone, weathered, pale yellowish gray (5Y812) to yellowish gray (5Y8/1), dries nearly white, relatively hard, brittle, bioturbated throughout, lichen-splotched, forms part of steep cliff face. Basal part weathers shaly, produces undercut part of ledge. Very thin shaly weathering interval, 70 cm above base, forms reentrant on cliff face. Unit contains sparse limonitized pyrite nodules 24.5 cm above base. FOSSILS: I. (Cremnoceramus) browni, I. (Cremnoceramus) inconstans, Pseudoperna congesta | | 1 16.0 |
| 25. | Bentonite, light olive gray (5Y5/2), forms deep reentrant on cliff face | | 1.5 |
| 24. | Chalky limestone, weathered, yellowish gray (5Y8/1), dries nearly white, relatively hard, brittle, bioturbated throughout, lichen-splotched, forms projecting, rounded ledge on cliff face. FOSSILS: I. (Cremnoceramus) browni, I. (Cremnoceramus) inconstans, Pseudoperna congesta | | 61.0 |
| 23. | Chalk, partly weathered, light olive gray (5Y5/2), with dark yellowish orange iron oxide staining locally, soft, weathers shaly, forms prominent reentrant on cliff face. FOSSILS: Inoceramus sp. (crushed, bowl-like valve), Pseudoperna congesta | | 3.1 |
| 22. | Chalky limestone, weathered, yellowish gray (5Y8/1) to pale grayish orange (10YR8/4), dries nearly white, relatively hard, brittle, sparsely bioturbated, lichen-splotched, forms projecting, rounded ledge on cliff face. FOSSILS: I. (Cremnoceramus) browni, I. (Cremnoceramus) inconstans, Pseudoperna congesta | | 51.9 |
| 21. | Bentonite, light olive gray (5Y5/2), biotitic, stained dark yellowish orange by iron oxide, forms deep reentrant on cliff face | | 3.1 |
| 20. | Chalky limestone, weathered, yellowish gray (5Y8/1) to grayish orange, dries nearly white, relatively hard, brittle, bioturbated, lichen-splotched, forms prominently projecting ledge on cliff face. FOSSILS: I. (Cremnoceramus) browni, Pseudoperna congesta | | 67.1 |
| 19. | Bentonite, light olive gray (5Y512), stained dark yellowish orange by iron oxide, speckled with biotite, with small selenite crystals, forms reentrant beneath overhang of unit 20 | | 1.5 |
| 18. | Chalk, partly weathered, light olive gray (5Y6/1), dries yellowish gray, relatively soft, weathers shaly, forms major reentrant on cliff face. Uppermost 6 cm harder, bioturbated, forms rounded, projecting ledge. Unit contains selenite seam, 3.1 cm thick, 7.6 cm below top. Unit contains sparse small limonite nodules. FOSSILS: I. (Cremnoceramus) browni, I. (Cremnoceramus) inconstans, Pseudoperna congesta, aerothoracican borings | | 47.2 |
| 17. | Chalky limestone, weathered, pale yellowish gray (5Y8/2) to pale grayish orange (10YR8/4), relatively hard, brittle, mostly bioturbated, lichen-splotched, forms projecting ledge on cliff face. Zone of softer chalk, 3.1 cm thick, 24.4 cm above base, weathers shaly, forms conspicuous reentrant just above middle of unit. Basal part of unit contains limonite nodules as much as 3 cm in diameter. FOSSILS: I. (Cremnoceramus) browni, I. (Cremnoceramus) inconstans, Pseudoperna congesta, sponge? borings. | | 48.8 |
| 16. | Chalky limestone, weathered, yellowish gray (5Y7/2) to pale grayish orange (10YR8/4), relatively hard, brittle, bioturbated, lichen-splotched, forms overhanging ledge above unit 15. Uppermost 6.0 cm and 3.0-cm-thick interval lying 18.3 cm below top of unit are softer, shaly weathering, form reentrants on cliff face. FOSSILS: I. (Cremnoceramus) browni, I. (Cremnoceramus) inconstans, Pseudoperna congesta, aerothoracican borings, Serpula? sp. | | 88.4 |
| 15. | Chalk, partly weathered, yellowish gray (5Y7/2) to moderate yellowish brown (10YR5/2), soft, bioturbated, forms major reentrant on cliff face. Middle part of unit highly bioturbated, weathers shaly, contains many limonitized burrow structures. FOSSILS: I. (Cremnoceramus) browni, I. (Cremnoceramus) inconstans, Pseudoperna congesta | | 42.7 |
| 14. | Chalky limestone, weathered, pale yellowish gray (5Y8/2), dries yellowish gray (5Y8/1) to nearly white, mottled in lower 30 cm with medium gray, relatively hard, brittle, bioturbated throughout, forms part of cliff face. Unit contains numerous blebs of pyrite, most of which is limonitized. FOSSILS: I. (Cremnoceramus) inconstans, I. (Cremnoceramus) browni, Pseudoperna congesta, acrothoracican borings. | | 88.3 |
| 13. | Chalk, olive gray (5Y4/1) below, light olive gray (5Y7/2) above, relatively soft, speckled sparingly, calcareous silty, bioturbated, weathers shaly, forms reentrant on steep cliff face. Unit contains sparse flakes of biotite. FOSSILS: I. (Cremnoceramus) inconstans, Pseudoperna congesta | | 9.2 |
| 12. | Chalky limestone, partly weathered, light olive gray (5Y6/1), dries yellowish gray (5Y8/1), relatively hard, brittle, bioturbated throughout, forms part of cliffface. Unit weathers shaly at top and in very thin zone lying 15.3 cm below top; latter shaly interval marked by reentrant. FOSSILS: I. (Cremnoceramus) inconstans, I. deformis, Pseudoperna congesta | | 70.0 |
| 11. | Chalk, olive gray (5Y4/1), calcareous silty, speckled sparingly, argillaceous, weathers shaly, forms small reentrant on cliff face | | 3.1 |
| 10. | Chalky limestone, weathered, pale yellowish gray (5Y812) to grayish yellow, dark yellowish orange where stained by iron oxide, relatively hard, brittle, bioturbated throughout, lichen-splotched, forms part of cliff face, weathers shaly in uppermost 15 cm. FOSSILS: Inoceramus deformis, Pseudoperna congesta | 1 | 13.0 |
| 9. | Chalk, olive gray (5Y4/1), calcareous silty, argillaceous, speckled sparingly, also speckled by black biotite grains, weathers shaly, forms reentrant on cliff face, may be bentonitic | | 3.1 |
| 8. | Chalky limestone, weathered, yellowish gray (5Y7/2), pale yellowish gray (5Y8/2) and pale grayish orange (10YR8/4), relatively hard, brittle, bioturbated throughout, forms part of cliff; very thin shaly weathering interval at base forms part of prominent reentrant on cliff face. FOSSILS: Inoceramus deformis, Pseudoperna congesta, Pycnodonte aucella | 1 | 31.2 |
| 7. | Chalky limestone, weathered, yellowish gray (5Y7/2), dries pale yellowish gray (5Y8/2), light olive gray (5Y6/1) in thin interval near middle, relatively hard, brittle, bioturbated throughout, forms part of cliff face. Unit weathers shaly at top and base; shaly weathering interval at top forms part of reentrant on cliff face. Unit contains irregular lenses of calcarenite, pale yellowish brown, hard, brittle, in lower 30 cm. FOSSILS: Inoceramus deformis, Pseudoperna congesta | 1 | 68.1 |
| 6. | Chalky limestone, partly weathered, light olive gray (5Y7/2), to weathered, grayish orange, relatively hard, brittle, bioturbated throughout, forms part of cliff face. Uppermost 3.1 to 6.2 cm weathers shaly, forms reentrant on cliff face. Basal part of unit weathers cavernous. Limonite nodules up to 3 cm in diameter, occur sparingly in zone lying 6.2 cm above base. Unit contains scattered thin lenses of calcirudite. Thin interval near center of bed is thinly cross laminated. FOSSILS: Inoceramus deformis, Pseudoperna congesta, Pycnodonte aucella | 1 | 37.3 |
| 5. | Chalky limestone, weathered, yellowish gray (5Y7/2) to pale grayish orange (10YR8/4), relatively hard, brittle, bioturbated throughout, forms part of cliff face. Uppermost 18.3 cm light olive gray (5Y6/1), bioturbated, weathers shaly, forms reentrant beneath unit 6. Limonitized pyrite nodules, less than 3 cm thick, occur in layer 18.3 cm below top of unit. FOSSILS: Inoceramus deformis, Pseudoperna congesta | 1 | 22.0 |
| 4. | Chalk, dark gray, in part weathered to light olive gray (5Y6/1), relatively hard, slightly calcareous silty, weathers shaly, contains sparse flakes of biotite, forms prominent reentrant on cliff face | | 3.1 |
| 3. | Chalky limestone, weathered, pale grayish orange (10YR8/4), grayish orange, and medium yellowish orange (10YR6/4), relatively hard, brittle, bioturbated throughout, forms part of cliff face. Limonite nodules, as much as 7.7 cm in diameter, occur in thin zone lying 24.5 cm above base of unit. FOSSILS: Inoceramus sp. (fragments), Pseudoperna congesta?, Pycnodonte aucella. | | 48.8 |
| 2. | Chalky limestone, weathered, yellowish gray (5Y8/1), relatively hard, brittle, bioturbated throughout, slightly silty, especially at base. Uppermost 3 cm is olive gray (5Y4/1), finely sandy, weathers shaly, forms small reentrant beneath unit 3. Unit contains small, scattered, cylindrical pyrite bodies. Lies with sharp contact on unit 1. FOSSILS: Pycnodonte aucella. | | 57.9 |
| Total thickness of Fort Hays Limestone Member | 21 | 93.8 |
| CARLILE SHALE |
| 1. | Shale, dark gray to olive gray (5Y4/1), sandy, with irregular very thin beds and laminae of light olive gray (5Y5/2), very fine grained sandstone. | | 30.1 |
| Measured thickness of Carlile Shale. | | 30.1 |
| Total thickness of measured section. | 38 | 61.6 |
