Core description of the Cretaceous and uppermost Jurassic section in the Amoco No. 1 Bounds well (SE1/4 NE1/4 sec. 17, T. 18 S., R. 42 W., Greeley County, Kansas). The upper interval from the Niobrara to the basal Graneros was described by R. W. Scott and M. J. Evetts, April, 1990; this description is enhanced by a more detailed description by Dean, et al. (1995). The lower part of the core was described in detail by P. C. Franks and R. W. Scott, July, 1988 for Amoco. The well spudded in Quaternary allu-vial gravels; coring of the Niobrara Formation, Smoky Hill Member, began at 529 ft. The original core measurements were made in feet; the tie to the well logs varies by different amounts at different depths. Cored Depth (ft) Description (aa = as above) (Thickness) NIOBRARA FORMATION Smoky Hill Chalk Member (65.7 cored) 529.0-535.9 Marl. Medium-dark-gray, local white specks. Lenticular calcarenite laminae with bioclasts (6.9) and foraminifers. Local Chondrites, Planolites, and burrow mottles; sparse inoceramid fragments. Scarce pyrite nodules. 535.9-538.0 Marly limestone. Light-gray to light-yellowish-gray. Moderately bioturbated: Chondrites, (2.1) Planolites. Inoceramid fragments. Marl interbed, 536.3-536.7 ft. 538.0-540.0 Marl, as above (aa). (2.0) 540.0-540.8 Marly limestone, aa. (0.8) 540.8-541.8 Marl, aa. (1.0) 541.8-543.0 Marly limestone, aa. (1.2) 543.0-544.2 Marl, aa; inoceramids. (1.2) 544.2-544.6 Marly limestone, aa. (0.4) 544.6-546.0 Marl, aa. (1.4) 546.0-547.0 Marly limestone, aa. (1.0) 547.0-554.0 Marl. Medium- to dark-gray. Thin-laminated. Sparse bioturbation.. Bentonite 6 cm thick (7.0) at 550 ft and 1 cm thick at 553. Inoceramus platinus at 551 ft. 555.0-576.0 Marl, aa. Inoceramus platinus? at 556 and 562.2 ft. Base gradational. (21.0) 576.0-577.0 Marly limestone. Light-gray to yellowish-gray. Moderately to well bioturbated: Planolites (1.0) and Teichichnus. Rare-common fish debris; abundant bivalve clasts; scattered oyster shell islands. Base sharp. 577.0-577.8 Marl, aa. I. platinus? at 577.5 ft. (0.8) 577.8-578.6 Marly limestone, aa. Pseudoperna congesta island at base. Base gradational. (0.8) 578.6-585.0 Marl, aa. Bentonite 1 cm thick at 582.5. P. congesta at 583; I. platinus? at 584.8 ft. (6.4) 585.0-586.0 Marly limestone, aa. Bentonite 1.5 cm thick at top. (1.0) 586.0-594.7 Marl. Medium-gray to medium-light-gray, speckled light-gray. Indistinct laminae. Sparse (8.7) oysters; I. platinus? at 592 ft. Sharp contact with below unit. Fort Hays Limestone Member (80.3) Hattin's Unit 9 (21.1) (Log depth top 595) 594.7-597.0 Marly limestone. Medium-light-gray. Irregular wavy laminae. Moderately bioturbated: (2.3) Planolites, Chondrites, Thalassinoides, and Teichichnus. Base gradational. 597.0-598.8 Marl, aa. Base sharply gradational. (1.8) 598.8-615.8 Marly limestone, aa to limestone. Light-gray to light-yellowish-gray. Well bioturbated: (17.0) Planolites, Thalassinoides, Teichichnus, and Zoophycus. Marl interbeds about 0.3 to 1.0 ft thick at 601.8, 602.8, 604.2, 608.0, and 610.0. Base sharp to slightly gradational. Hattin's Unit 8 (15.2) (Log depth top 611) 615.8-616.2 Marl, aa. (0.4) 616.2-631.0 Limestone. Very light gray to white. Well bioturbated: Planolites, Chondrites, Teichichnus, (14.8) and Zoophycus. Marl interbeds 0.1-0.2 ft thick at 618, 619, 622, 626, 628, and 629 ft. Bentonites 2-5 cm thick at 620, 623, and 629 ft. Basal contact sharp to stylolitic. Hattin's Unit 7 (9.0) (Log depth top 631) 631.0-640.0 Marl. Medium-gray. Calcisiltite laminae with inoceramid prisms. Slightly to moderately (9.0) bioturbated: Planolites and Chondrites. Limestone interbeds 0.2-2.0 ft thick, light-gray to white; bioturbated: Planolites, Chondrites, Teichichnus, and Zoophycus. Common to abun-dant inoceramid and oyster fragments. Base abruptly gradational. Hattin's Unit 6 (20.0) (Log depth top 644) 640.0-660.0 Limestone. Light-gray to light-yellowish-gray. Medium- to thick-bedded units separated by (20.0) beds of marl 0.4-0.8 ft thick. Well bioturbated: Planolites, Chondrites, Teichichnus, Zoophycus, and Thalassinoides. Common to abundant inoceramid and oyster fragments. Hattin's Unit 5 (8.2) (Log depth top 660) 660.0-660.1 Shale. Dark-gray. Inoceramid prisms. (0.1) 660.1-661.0 Marl. Medium-dark-gray. Burrow mottles. (0.9) 661.0-663.0 Interbedded bioturbated limestone and marl with inoceramid prisms. (2.0) 663.0-667.0 Limestone. Light-gray. Bioturbated. Inoceramid prisms. (4.0) 667.0-668.2 Interbedded marl and limestone , aa. Sharp contacts. (1.2) Hattin's Unit 4 (6.8) (Log depth top 668) 668.2-675.0 Limestone. Light-gray. Top gradational with wispy clay laminae. Sandy (quartz) below (6.8) 672.0 ft. Well bioturbated: Planolites, Thalassinoides, and Teichichnus. Lower contact appears gradational because of the intense reworking of sand into carbonate sediment. CARLILE SHALE Codell Sandstone Member (80) 675.0-676.5 Sandstone. Medium-light-gray. Fine- to medium-grained. Moderately sorted. Clay and silt (1.5) laminae. Well bioturbated: Chondrites, Planolites, and Teichichnus. 676.5-679.8 Calcareous sandstone. Light-olive-gray to light-yellowish-gray. Fine-grained, well sorted. (3.3) Well bioturbated: same assemblage and Zoophycus. Clasts of calcarenite up to 3 cm in diameter in upper part. 679.8-753.0 Sandstone. Medium-gray. Medium-grained grading downward to fine- and very fine (73.2) grained. Fine-grained sand and silt mottles. Clay and silt laminae. Abundant Teichichnus and Chondrites in upper part decrease downward. 753.0-755.0 Mudstone. Medium-dark-gray. Silt mottles and lenses; discontinuous ripple laminae. (2.0) Bioturbated. Gradational lower contact. Bluehill Shale Member (25) 755.0-780.0 Shale. Dark-gray. Fissile. Bioturbated locally: Planolites, Chondrites, and Teichichnus. (25.0) Inoceramus costellatus and Prionocyclas hyatti at 761.8 ft. Sparse inoceramid and ammonite debris locally below 773 ft. Bentonite 2 cm thick at 784 ft. Fairport Chalk Member (125.8) 780.0-815.0 Calcareous shale. Dark-gray. Fissile. Sparse calcisiltite laminae. Abundant inoceramids. (35.0) Bentonites 1-3 cm thick at 793.5, 797.0, 807.4, and 807.6 ft. Inoceramus subhercynicus? at 813.8 ft. 815.0-865.0 Calcareous shale. Dark-gray. Fissile. Very thin calcisiltite laminae common. Inoceramus (50.0) subhercynicus? at 834.8, 841.9, and 844.6 ft; Inoceramus labiatus at 851.6 ft. 865.0-905.8 Marl. Dark-gray. Fissile. Few scattered, thin calcisiltite laminae. Scarce burrows. Benton- (40.8) ite 6 cm thick at 902.2 ft. Scarce phosphate nodules at 905. GREENHORN FORMATION (124.1) Bridge Creek Limestone Member (81.2) Marker Bed PF-3 (10.2) 905.8-906.1 Limestone. Medium-gray. Bioturbated. Pyrite. Grades into below. (0.3) 906.1-906.4 Marl. Medium-gray. Slightly bioturbated. (0.5) 906.4-906.5 Limestone, aa. (0.1) 906.5-916.0 Marl, aa. Fine-grained calcarenite 2-8 cm thick at 908.3, 910, and 912.3 ft. (9.5) Marker Bed PF-2 (5.8) 916.0-916.4 Limestone. Light-gray to yellowish-gray. Inoceramid debris and pyrite. Base gradational. (0.4) 916.4-921.8 Marl, aa. (5.4) Marker Bed PF-1 = JT-13 (8.9) 921.8-922.0 Limestone, aa. (0.2) 922.0-922.5 Marl, aa. (0.5) 922.5-922.7 Limestone, aa. (0.2) 922.7-923.5 Marl, aa. (0.8) 923.5-923.9 Limestone, aa. Bentonite 2 cm thick at base. (0.4) 923.9-929.5 Marl, aa. (5.6) 929.5-929.8 Limestone, aa. (0.3) 929.8-930.7 Marl, aa. Bentonite 2.5 cm thick at 930.0. (0.9) Marker Bed JT-12 (7.3) 930.7-931.0 Limestone, aa. (0.3) 931.0-938.0 Marl. Dark-gray. Calcisiltite lenses and laminae common, possibly rippled. Inoceramid (7.0) debris common. Base gradational. Marker Bed JT-11 (10.8) 938.0-938.4 Limestone. Medium-gray. Base gradational. (0.4) 938.4-942.7 Marl, aa. Inoceramids abundant at 940.0 ft. Calcarenite laminae. (4.3) 942.7-946.0 Argillic limestone. Medium-gray. Upper 0.3 ft calcarenitic grading down into marl. (3.3) Bentonite 2 cm thick at 945.3. Bioturbated. Mytiloides subhercynicus at 943 ft; Mytiloides mytiloides at 943.9, 944.0, 945.5, and 945.8 ft. 946.0-946.5 Limestone. Medium-gray. Bioturbated. Inoceramid debris. (0.5) 946.5-948.8 Marl, aa. Bioturbated. Abundant inoceramids. Limestone beds 2 cm thick at 947.4 and (2.3) 947.8 ft. Bentonite 2 cm thick 1 cm above base. Marker Bed JT-9 (6.2) 948.8-949.2 Limestone, aa. Distinct Thalassinoides burrows. (0.4) 949.2-950.0 Marl, aa. (0.8) 950.0-950.2 Limestone, aa. (0.2) 950.2-951.1 Marl, aa. Mytiloides mytiloides at 950.5. (0.9) Marker Bed JT-9 (6.2), Ct'd. 951.1-951.4 Limestone, aa. (0.3) 951.4-952.3 Marl, aa. (0.9) 952.3-952.5 Limestone, aa. (0.2) 952.5-955.0 Marl, aa. Scattered cm-thick calcisiltite laminae and rare Inoceramus opalensis?. (2.5) Marker Bed JT-6 (7.2) 955.0-955.1 Limestone, aa. (0.1) 955.1-956.5 Marl, aa. Base sharp. (1.4) 956.5-956.7 Limestone, aa. Base gradational by bioturbation. (0.2) 956.7-957.7 Marl, aa (1.0) 957.7-958.0 Limestone, aa. (0.3) 958.0-959.5 Marl, aa. (1.5) 959.5-959.7 Limestone, aa. (0.2) 959.7-960.7 Marl, aa. (1.0) 960.7-960.9 Limestone, aa. (0.2) 960.9-962.2 Marl, aa. (1.3) Marker Bed JT-1= HL-5 (14.1) 962.2-962.7 Limestone, aa. Distinct Thalassinoides burrows. (0.5) 962.7-962.9 Bentonite bed. (0.2) 962.9-964.7 Marl, aa. Inoceramus opalensis at 963.4 ft. Base gradational by interlamination. (1.8) 964.7-965.0 Limestone, aa. Base sharp. (0.3) 965.0-965.8 Marl, aa. (0.8) 965.8-966.0 Limestone, aa. (0.2) 966.0-967.6 Marl, aa. Bentonite 5 cm thick at 967.0 ft, identified as Elder's (1985) bed "C" by Dean et (1.6) al. (1995). Inoceramus opalensis at 966.4 ft. 967.6-968.0 Marly limestone. Medium-gray. Bioturbated (0.4) 968.0-969.0 Marl, aa. Mytiloides opalensis at 968.6 ft. del C-13 = -25.7 %. (1.0) 969.0-969.1 Limestone, aa. (0.1) Marker Bed JT-1= HL-5 (14.1), Ct'd. 969.1-969.8 Marl, aa. (0.7) 969.8-969.9 Limestone, aa. (0.1) 969.9-970.9 Marl, aa. (1.0) 970.9-971.1 Limestone, aa. Teichichnus, Thalassinoides, and Planolites. (0.2) 971.1-971.5 Marl, aa. (0.4) 971.5-971.6 Limestone, aa. (0.1) 971.6-972.5 Marl, aa. (0.9) 972.5-972.7 Limestone, aa. (0.2) 972.7-973.6 Marl, aa. Mytiloides opalensis at 974.4. del C-13 = -23.8% and TOC = 4.7% at 973.33 ft. (0.9) 973.6-973.9 Limestone, aa. (0.3) 973.9-974.8 Marl, aa. Noncalcareous black clay, 4 cm thick at 974.33 ft; del C-13 = -23.5 %, TOC = (0.9) 5.5%. 974.8-974.9 Limestone, aa. (0.1) 974.9-975.3 Marl, aa. (0.4) 975.3-975.4 Limestone, aa. (0.1) 975.4-976.0 Marl, aa. del C-13 = -23.6 % and TOC = 7.1% at 975.45 ft. (0.6) 976.0-976.3 Bentonite. White to light-gray. Identified by Dean et al. (1995) as Elder's (1985) bed "B". (0.3) Grades sharply into below. Marker Bed HL-3 (6.4) 976.3-977.1 Limestone. Very light-gray. Very bioturbated: Thalassinoides. (0.8) 977.1-977.5 Marl, aa. (0.4) 977.5-977.7 Limestone. Very light gray. Calcisiltite with climbing ripples. (0.2) 977.7-978.7 Marl, aa. del C-13 = -23.7 % and TOC = 6.1% at 978.17 ft. (1.0) 978.7-979.0 Limestone. Very light gray to yellowish-gray. Very bioturbated. (0.3) 979.0-981.2 Marl, aa. del C-13 = -23.2% and TOC = 2.8% at 979.73 ft; del C-13 = -24.2% and TOC = (2.2) 1.8% at 980.79 ft. 981.2-982.6 Missing core. (1.4) 982.6-982.7 Bentonite. Elder's (1985) bed "A" identified by Dean et al. (1995). (0.1) Marker Bed HL-2 (2.8) 982.7-983.7 Limestone. Yellowish-gray to light-gray. Well bioturbated: Thalassinoides. Base sharp. (1.0) 983.7-985.5 Marl. Medium-gray. Slightly bioturbated. Bentonite 3 cm thick at 984.3 ft. (1.8) Marker Bed HL-1 (1.5) 985.5-987.0 Limestone, aa. (1.5) Hartland Shale Member (16.9) 987.0-988.2 Calcareous shale. Dark-gray. Scattered calcisiltite laminae. (1.2) 988.2-988.5 Limestone. Medium-gray. Slightly bioturbated. (0.3) 988.5-992.0 Calcareous shale., aa. Rare pyrite. (3.5) 992.0-992.2 Calcisiltite. Medium-gray. Ripple-laminated. Inoceramid debris. (0.2) 992.2-997.7 Calcareous shale, aa. Rare inoceramids. (5.5) 997.7-998.0 Calcisiltite, aa. Thin shale lamina 1 cm thick divides bed. (0.3) 998.0-999.6 Calcareous shale, aa. (1.6) 999.6-999.8 Calcisiltite, aa. Inoceramus prefragilis?. (0.2) 999.8-1003.9 Calcareous shale, aa. Four cm-thick calcisiltite laminae at 1002, 1002.5, 1003, and 1004 (4.1) ft. Lincoln Limestone Member (26) 1003.9-1009.5 Calcareous shale, aa. Ripple-laminated; 15-cm-thick, laminated calcisiltite bed at top; 3- (5.6) cm-thick laminated calcisiltite at base. Four 1-cm-thick bentonite beds at 1004.4, 1004.6, 1007.5, and 1008.8 ft. Inoceramus prefragilis? at 1005.5, 1007.4, and 1008.5 ft; Entolium gregarium? at 1005.5 ft. 1009.5-1028.8 Calcareous shale, aa. Calcisiltite laminae scattered throughout. Bentonite laminae at (19.3) 1009.8, 1010.6, 1016.8, 1020.8, 1026.2, and 1028.0. 1028.8-1029.9 Succession of three beds: limestone, aa, 0.3-ft thick, on calcareous shale, aa, 0.5-ft thick, (1.1) on ripple-laminated calcisiltite aa, 0.3 ft thick. GRANEROS SHALE (85.8) "Upper Interval of Graneros Shale" (53.7) 1029.9-1032.0 Calcareous shale, aa. Bentonite 1 cm thick at top; ripple-laminated calcisiltite 2 cm thick (2.1) at base. 1032.0-1046.0 Calcareous shale. Dark-gray. Calcisiltite laminae common in upper part, becoming scarce (14.0) below. Bentonite 2 cm thick at 1037.2 ft. Inoceramus prefragilis? at 1034.4 ft; Inoceramus pictus? at 1043.5 ft. 1046.0-1046.4 Bentonite. Light-gray to white stained yellow. "X" Bentonite Marker Bed. (0.4) 1046.4-1054.0 Shale. Dark-gray. Calcareous. Fissile. Sparse inoceramids and oysters. Inoceramus (7.6) rutherfordi at 1053.8; Inoceramus pictus? at 1051.3 ft; Ostrea beloiti at 1048.0, 1051.6, 1052.2, and 1053.5 ft; Anomia sp. at 1048.0 ft. Scarce pyrite. 1054.0-1075.0 Shale, aa. Inoceramus rutherfordi at 1054.4, 1056.0, 1056.9, 1057.8, 1059.8, 1064.1, (21.0) 1064.8, 1067.6, and 1068.9 ft; Inoceramus arvanus at 1071.3, 1073.3, and 1074.0 ft. 1075.0-1083.6 Shale. Medium-dark-gray. Calcareous. Thin-laminated; laminae inclined 5o. Bluish-gray (8.6) bentonite bed at 1078.5 ft. Scarce calcarenite lenses and laminae, most abundant in basal 0.5 ft. Scattered Inoceramus fragments £6 cm long, £0.5 cm thick. Scarce subvertical bur-rows £3 mm diameter filled with calcite and shell debris; Planolites(?) burrows in basal 0.5 ft along calcarenite laminae. Sparse slickensided fractures inclined 50o to shale laminae. Inoceramus arvanus at 1077.3, 1079.8, and 1085.2 ft. Grades into below by alternation. Thatcher Limestone Member (1.7) 1083.6-1085.3 Limestone. Very light to medium-gray. Micrite and very fine to fine-grained, calcarenite. (1.7) Thin-laminated to wavy laminated; possible small-scale hummocks; contorted laminae chiefly near base: Medium-dark-gray shale laminae; bentonite lamina at 1084.7 ft. Scat-tered Inoceramus fragments. Scarce pyrite blebs in calcarenite and on shell fragments. Sharp, erosional contact with below. "Lower Interval of Graneros Shale" (30.4) 1085.3-1115.0 Shale. Medium-dark-gray. Interlaminated very fine- to fine-grained calcarenite and silty (29.7) to very fine grained sandstone. Thin-laminated; laminae inclined 5o, locally 10o. Calcare-ous grading down to noncalcareous; most calcareous in upper 3.7 ft where thin beds and laminae of calcarenite similar to above scattered through shale; calcarenite beds show thin foreset ripple laminae, sparse load casts, and contorted bedding. Shale also locally silty, and pyritic as from 1113.2 to 1113.5 ft. Silt to very fine grained sandstone mainly in lower 1 ft. Bluish-gray bentonite laminae at 1105.5, 1105.9, 1110.0, and 1113.5 ft. Scarce Inoceramus and other shell fragments throughout; sparse Planolites-like burrows in calcarenite zones. Scarce yellowish-brown siderite(?) nodules £1 cm in long dimension; irregular pyrite nodules concentrated along bentonite layers. Sparse slickensided fractures. Bioturbated silty base in sharp, irregular contact with below. Transgressive surface. 1115.0-1115.7 Sandstone. Light- to dark-gray. Fine-grained, poorly sorted. Contorted shale laminae. (0.7) >90% bioturbated; sparse Skolithos; most burrows indeterminate. Abundant interstitial clay, pyrite, sparse calcite cement, possible siderite cement. Base Graneros Shale. Contact with Dakota Formation below not preserved because of washing of underlying Dakota shale during coring, but contact probably sharp because erosional: base of sandstone sharp and irregular. DAKOTA FORMATION "Upper Dakota Interval" (55.5) Depositional Unit 20 1115.7-1117.0 Shale. Medium-gray; brown overtones. Thin-laminated. Sparse silt- and sand-filled sub- (1.3) horizontal burrows and contorted silty to very fine grained sandstone laminae. Skolithos and indeterminate trace fossils. Abundant pyrite along probable burrows near base. Sharp contact with below marked by distinct upward decrease in siltstone and sandstone. Possible transgressive surface at base but unit forms upward fining package with below. 1117.0-1118.3 Sandstone. Dark-gray grading down to light-gray. Fine-grained, sorting moderate. Con- (1.3) torted thin laminae; 80% bioturbated; indeterminate burrow mottling; contorted and lenticular ripple laminae at base. Abundant interstitial clay where dark; scattered pyrite nodules; probable quartz overgrowths. Carbonaceous near base where interbedded clay is brownish black to dark brown and pyritic. Contact with below sharp, erosional. Trans-gressive surface. Depositional Unit 19 1118.3-1118.8 Interlaminated sandstone and shale. Light-gray to brownish-gray interlaminated with (0.5) dark-gray. Sandstone very fine grained. Laminae even and thin; also lenticular to con-torted. 30-60% bioturbated: Chondrites(?), indeterminate subhorizontal burrows. Pyrite nodules £5 cm long at top. Sharp, planar contact with below. Forms upward coarsening package with below. 1118.8-1119.8 Siltstone. Medium-gray; pale-brown overtones. Indistinct, crinkled thin laminae. Sparse (1.0) horizontal and inclined burrows £ 3 mm in diameter; more intensely bioturbated near base where laminae are contorted. Clayey; scattered light-gray, clay-poor silt laminae; sparse fine-grained sand reworked into lower parts by burrowing of next below. Scarce pyrite nodules £1 cm long. Contact with below sharp, inclined, irregular. Depositional Unit 18 1119.8-1122.3 Sandstone grading down to interbedded sandstone and shale. Light- and dark-gray. Sand- (2.5) stone very fine- to fine-grained; shale silty to sandy. Contorted and wavy thin beds and laminae in sandstone; lenticular and thin, even laminae in shale. Intensely bioturbated above, 5% bioturbated below where shale laminae abundant; burrows mainly subhori-zontal Planolites or Scolicia; also Monocraterion, Teichichnus, and Chondrites. Abundant quartz overgrowths; irregular pyrite nodule 5 cm long in upper sandstone cuts across bed-ding; scattered pyrite blebs elsewhere. Carbon flecks and fragments in sandstone; carbon flecks and mica flakes on shale laminae. Sharp, wavy contact with below. Upward coar-sening unit. Depositional Unit 17 1122.3-1125.2 Sandstone grading down to interbedded sandstone and shale grading down to shale. Light- (2.9) and dark-gray. Sandstone very fine grained; shale silty. Intensely bioturbated and indis-tinct wavy laminae above; wavy to lenticular burrowed laminae below; abundant Chon-drites in upper sandstone; Skolithos, Planolites, and indeterminate burrows in interlami-nated sandstone and shale. Abundant quartz overgrowths, scattered pyrite blebs in sand-stone. Scarce glauconite, carbon flecks and fragments in sandstone; mica flakes on shale laminae. Upward coarsening unit similar to above, but grades sharply into below where Chondrites burrows cross contact. Depositional Unit 16 1125.2-1126.6 Sandstone. Light-gray grading down to grayish-olive and brownish-gray. Very fine (1.4) grained. Contorted and burrowed laminae; burrowing more intense downward; Monocra-terion, Skolithos, and indeterminate burrows; Chondrites near top. Abundant quartz over-growths; abundant pyrite cement in lower parts where grayish-olive. Abundant carbon flecks and fragments. Contorted contact with shale below; brownish-black clay churned into basal parts of sandstone. Forms upward coarsening package with below. 1126.6-1128.6 Shale. Brownish-black. Silty. Thin-laminated; laminae inclined about 5o and contorted in (2.0) upper 0.5 ft; also scattered, thin, very fine grained sandstone laminae in upper 0.5 ft; sandstone laminae burrowed and cemented with pyrite. Sparse contorted siltstone fragments near base reworked from below. Sparse carbonized leaves and plant imprints. Sharp wavy contact with below. Transgressive surface. Depositional Unit 15 1128.6-1129.4 Siltstone. Moderate-brownish-gray. Clayey. Indistinct inclined bedding above, no obvious (0.8) bedding below; nodular weathering textures in upper part. Grades sharply into below. Forms upward fining package with below. 1129.4-1131.8 Sandstone. Pinkish-gray to pale-brownish-gray and grayish-brown. Very fine grained, (2.4) silty. Bedding mainly indistinct or contorted; sparse contorted, wavy thin laminae where brownish-gray and interstitial clay abundant. Well bioturbated; Planolites and indeter-minate burrows. Quartz overgrowths; sparse pyrite nodules £3 cm across. Possible root casts and synaeresis cracks. Sharp wavy contact with below. Depositonal Unit 14 1131.8-1133.6 Mudstone grading down to siltstone. Dusky-brown grading down to yellowish-gray (1.8) grading down to dark-gray. Contorted, wavy laminae in lower 1.5 ft, some sandy; pos-sible disturbance of bedding by plant roots in lower 1.5 ft. Abundant slickensided fractures in mudstone. Scattered pyrite or marcasite. Abundant carbon flecks and fragments; lower parts of siltstone carbonaceous. Grades into below by alternation. Forms overall upward fining package with intervals below. 1133.6-1138.6 Sandstone. Dark-gray interlaminated with pale-brownish-gray and pale-yellowish-gray. (5.0) Very fine grained; silty, clayey. Contorted and lenticular laminae and thin beds; abundant interlaminated carbonaceous silty clay films. Abundant woody debris and carbon flecks and fragments. Pyrite nodules and impregnations localized by woody debris; abundant quartz overgrowths in clean sandstone. Dark-gray, carbonaceous, laminated siltstone in basal 0.3 ft. 1138.6-1171.2 Interlaminated sandstone, siltstone, and silty shale. Light-yellowish-gray to medium-gray (32.6) interlaminated with medium-dark-gray. Sandstone fine-grained, well sorted. Wavy to con-torted laminae and thin laminae, inclined 10 to 15o; small-scale load casts(?); sparse pene-contemporaneous faults showing 5 cm or more offset. 50-70% bioturbated; trace fossils Planolites-like and indeterminate. £40 % interlaminated to interbedded siltstone and shale in upper parts; £20 % in lower parts. Abundant quartz overgrowths in clean sandstone; calcite cement from 1169.5 to 1170.0 ft; irregular pyrite nodules and cement from 1169 to 1170 ft and at base. Sparse glauconite; abundant interstitial carbon and carbon flecks and fragments; carbonized wood fragments £2 cm long. Sparse vertical fractures 1169 to 1170 ft. Contact with below sharp, irregular, erosional. Base "Upper Dakota Interval." Transgressive surface and sequence boundary. "Lower Dakota Interval" (115.3) Depositional Unit 13 1171.2-1176.3 Mudstone grading down to clayey sandstone. Yellowish-gray; becomes lighter with depth. (5.1) Sandstone very fine to fine-grained and silty. No obvious bedding in upper parts; local churned fabrics or clasts of sandstone in sandy mudstone, 1175 to 1176 ft; inclined and ripple laminae in basal 0.5 ft. Scattered slickensided fractures in mudstone; mudstone plastic when wet; may contain expandable clay minerals. Quartz overgrowths in basal 0.5 ft of sandstone where clean; sparse pyrite blebs in mudstone. Sparse muscovite flakes and black opaque grains in sandstone. Sharp contact with below. Upward fining interval. Depositional Unit 12 1176.3-1177.2 Mudstone. Yellowish-gray grading down to medium-gray. Contorted laminae and lenses (0.9) of very fine grained sandstone near top and base; synaeresis cracks near base. Sparse carbon fragments. Sharp, wavy contact with below; lenticular laminae of very fine grained sandstone impart a transitional aspect to the boundary. Forms upward fining package with below. 1177.2-1179.7 Sandstone. Light- to medium-gray. Very fine to fine-grained; well sorted. Thin ripple and (2.5) wavy laminae, commonly contorted and bioturbated; scattered brownish-gray shale lami-nae disrupted by bioturbation; burrows mainly subhorizontal, Planolites-like. Abundant quartz overgrowths. Abundant angular to contorted clay-rock fragments £4 cm long in upper 1 ft; scattered carbon flecks and fragments; possible carbonized rootlets and root casts. Sharp, wavy, erosional contact with below. Depositional Unit 11 1179.7-1183.1 Mudstone. Yellowish-gray. Contains scattered clots and clasts of siltstone and fine- (3.4) grained clayey sandstone; perhaps bioturbated by roots. Siderite spherules <1 mm in diameter in upper 1 ft and near base (identification confirmed by x-ray diffraction); pyrite blebs in siltstone clots. Probable fossil soil. Contact with below sharply gradational. Forms upward fining package with below. 1183.1-1185.8 Sandstone. Light-gray. Very fine to fine-grained, well sorted. Indistinct, horizontal to (2.7) wavy and contorted laminae; contorted gray shale laminae and clasts near base. Scattered pyrite blebs and nodules £2 cm across. Sharp, slightly wavy contact with below. Depositional Unit 10 1185.8-1188.6 Mudstone grading down to claystone. Medium-gray grading down to brownish-gray. (2.8) Abundant slickensided fractures. Sharp, irregular contact with below. Combined with below as a single depositional package. 1188.6-1189.8 Claystone grading down to mudstone. Yellowish-gray grading down to light-gray. Sparse (1.2) slickensided fractures. Sharp, wavy contact with below. Depositional Unit 9 1189.8-1192.2 Sandstone. Light-gray to light-yellowish-gray. Very fine to fine-grained. Indistinct ripple (2.4) laminae; sparse small-scale trough cross-laminae; sparse contorted laminae inclined 15o near base. Sparse clay films, carbon flecks, mica flakes along laminae. Sparse quartz over-growths. Grades sharply into below across burrowed contact. Forms upward coarsening package in combination with intervals below. 1192.2-1194.4 Sandstone. Pale-grayish-orange; scattered grayish-brown laminae; common yellowish- (2.2) brown "limonite" stain. Very fine grained. Ripple-laminated; some current ripples show low angles of climb; contorted laminae at top and bottom. 10% bioturbated: chiefly Sko-lithos; Rosella(?); Teichichnus(?) at base. Scattered brown to brownish-gray silty to sandy laminae cemented by siderite(?), mostly near top where bedding is most contorted and disrupted by burrowing; local brown siderite cement. Scattered carbon flecks, mica flakes. Contact with below not preserved but probably sharp. 1194.4-1197.1 Sandstone to siltstone interlaminated with shale. Pale-brownish-gray to grayish-orange (2.7) interlaminated with medium-gray showing brown overtones. Sandstone very fine grained, silty; basal 0.5 ft mostly silty shale containing thin lenticular beds of ripple-laminated very fine to fine-grained sandstone. Laminated and thin-laminated; lenticular laminae disrup-ted by burrows, mainly Planolites-like, also indeterminate. Sparse yellowish-brown "limo-nite" stain, probably where cemented by siderite. Sparse carbon flecks and mica flakes on bedding. Sharp erosional and burrowed contact with below. Depositional Unit 8 1197.1-1204.8 Sandstone. Very light gray to pinkish-gray; dark-gray showing brown overtones in upper (7.7) 0.4 ft. Fine-grained, very well sorted; very fine to fine-grained in top 0.4 ft. Thin-bedded to laminated; laminae wavy to lenticular; scattered gray silty shale partings; sparse ripple-scale trough cross-laminae near base. Variable bioturbation, 5 to 100%, most abundant at base and near top; Skolithos, "elongate" Teichichnus £3 mm across, Planolites-like, and indeterminate trace fossils. Abundant quartz overgrowths; siderite(?) cement and abundant carbonaceous matter in top 0.4 ft; scattered carbon flecks and fragments elsewhere. Sparse vertical fractures. Sharp, erosional, burrowed contact with below. Upward fining interval. Depositional Unit 7 1204.8-1205.6 Lignite grading down to mudstone. Brownish-black above, yellowish-gray below. No obvi- (0.8) ous lamination in upper parts of lignite, laminated below; slickensided fractures and car-bonized rootlets in mudstone. Mudstone plastic when wet; probably contains expandable clay minerals. Sharp, irregular contact with below. Forms thin, lignite-capped depositional package with upward coarsening interval next below. Mudstone interpreted as part of an hydromorphic soil. 1205.6-1206.5 Sandstone grading down to siltstone and shale. Pale-pinkish-gray grading down to (0.9) medium-gray. Sandstone very fine grained. Wavy, lenticular and bioturbated laminae in sandstone; thin laminae in siltstone and shale. Carbonized rootlets and root casts in upper parts; Planolites-like burrows. Quartz overgrowths; pyrite or marcasite nodules £2.5 cm diameter; bedding contorted around nodules. Sharp irregular contact with below. 1206.5-1210.2 Sandstone. Yellowish-gray to light-gray and pale-brownish-gray. Fine-grained, well (3.7) sorted. Laminated to thin-laminated; sparse current-ripple laminae; scattered zones show-ing wavy to crinkly, dark-gray, carbonaceous shale partings and laminae; scarce dish structures. <5% bioturbated. Trace fossils in shale laminae, small, <3 mm across, Planolites-like. Abundant quartz overgrowths; common pyrite or marcasite cement, also as nodules £6 cm long. Abundant carbon flecks and fragments; mica flakes on bedding sur-faces. Vertical fractures. Sharp, wavy contact with below. In combination with intervals below, forms generally upward coarsening package. 1210.2-1213.2 Interlaminated sandstone and shale grading down to mudstone. Sandstone yellowish-gray (3.0) to grayish-orange; shale and mudstone medium- to dark-gray. Sandstone very fine grained; lower part of mudstone sandy. Wavy, lenticular, and thin laminae in sandy inter-val; sparse starved current ripples. <5% bioturbated; trace fossils chiefly small, Planolites-like; scarce escape burrows. Abundant carbon flecks and fragments; sparse leaf imprints. Scarce pyrite localized on carbonaceous matter; mica flakes on bedding surfaces. Sharp, somewhat wavy contact with below. 1213.2-1217.1 Mudstone and shale interbedded with sandstone. Mudstone and shale medium- to dark- (3.9) gray; sandstone yellowish-gray, pale-yellowish-brown, and light-gray. Sandstone domi-nantly very fine grained, some fine-grains. Abundant contorted bedding; contorted sand-stone layers £0.6 ft thick separated by mudstone and shaly thin beds; sandstone mostly thin-laminated; laminae locally crinkled to lenticular. Degree of bioturbation increases downward from 5% to 80%; trace fossils mostly small, Planolites-like. Abundant carbon flecks and fragments; carbonized wood debris in basal 0.6 ft. Sharp contact with below inclined about 5o. Depositional Unit 6 1217.1-1217.5 Lignite. Black grading down to brownish-black. Thin-laminated. Abundant woody tissue (0.4) (fusain). Contact with sandstone below sharply gradational by alternation and root pene-tration. Forms lignite-capped depositional package with upward coarsening intervals below. 1217.5-1220.8 Sandstone. Medium-gray grading down to light-gray and light-yellowish-gray. Very fine (3.3) to fine-grained, moderately well sorted. Bedding contorted in top 0.7 ft; horizontal and wavy laminae; small-scale trough cross-laminae in sets £0.15 ft thick; scattered, wavy, silty shale laminae in lower 2 ft. Scarce Planolites and Chondrites burrows along shale lami-nae. Abundant quartz overgrowths; scarce siderite(?) spherules. Abundant carbon flecks, fragments in top 0.3 ft; carbonized rootlets and root casts in next 0.5 ft; mica flakes on shale partings. Sparse vertical fractures. Sharp wavy contact with below actually grada-tional by alternation. Forms generally upward coarsening package with next below. 1220.8-1228.1 Interlaminated sandstone and shale grading down to interlaminated siltstone and sand- (7.3) stone; base of unit marked by 0.2-ft silty mudstone. Light-yellowish-gray sandstone alter-nating with medium-gray shale showing brown overtones. Proportions of shale increase downward in upper parts of unit; sandstone very fine- to fine-grained above; coarse silt to very fine grained sandstone intercalated with fine-grained sandstone in lower parts of unit. Ripple- and wavy laminae give way downward to lenticular laminae. Degree of bioturba-tion increases downward in basal 1.2 ft, nearly 100% near base. Trace fossils chiefly Planolites- and Chondrites-like; Chondrites-like burrows mainly in middle and upper parts of interval and in mudstone at base of interval; Skolithos and Teichichnus(?) in basal 1.5 ft. Abundant quartz overgrowths near top and base. Scattered carbon flecks and frag-ments; mica flakes on bedding surfaces. Mudstone at base in sharp contact with below. Depositional Unit 5 1228.1-1228.4 Lignite. Brownish-black. Thin-laminated. Abundant carbonized plant tissue (fusain). (0.3) Sharp contact with below marked by carbonized rootlets. Forms thin, lignite-capped depo-sitonal package with below. 1228.4-1230.1 Sandstone. Light-gray to brownish-gray; Very fine- to fine-grained, moderately well (1.7) sorted. Horizontal to inclined laminae and thin laminae; ripple and lenticular laminae near base; churned fabrics in upper parts from root action; abundant very dark gray shaly laminae. 5% bioturbated near base. Trace fossils chiefly carbonized rootlets and root casts above; Skolithos below. Quartz overgrowths. Abundant carbonaceous matter and mica flakes on shaly laminae. Sharp contact with below. Depositional Unit 4 1230.1-1230.3 Lignite. Brownish-black. Silty to sandy. Thin- to wavy laminated. Slickensided fractures. (0.2) Sharp, wavy contact with below. Forms lignite-capped depositional package with upward coarsening interval below. 1230.3-1235.0 Sandstone grading down to mudstone grading down to carbonaceous shale. Moderate- (4.7) light-brownish-gray grading down to medium-gray grading down to dark-gray. Sandstone fine-grained. Churned fabric in upper part of sandstone from root action; laminae below disrupted and contorted; no obvious bedding in mudstone; shale thinly laminated; 2-cm-thick sandstone layer enclosed by shale. Carbonized rootlets and root casts in upper parts of sandstone; Teichichnus(?) near middle. Quartz overgrowths in sandstone; siderite nodules in mudstone. Abundant carbon flecks and fragments, carbonized woody debris; mica flakes on bedding. Sharp, wavy contact with below. Upward coarsening interval. Depositional Unit 3 1235.0-1256.5 Sandstone grading down to siltstone. Light-brownish-gray to very pale-orange. Fine- (21.5) grained grading down to silt-sized; fine-grained sandstone very well sorted. Upper part of sandstone churned by root action; wavy ripple and even laminae; low-angle climbing-ripple structures where shaly laminae present; possible oscillation-ripple structures; scarce shaly laminae; no obvious bedding in siltstone at base of unit. Carbonized rootlets in upper part of sandstone; Skolithos(?) burrows in siltstone. Quartz overgrowths in fine- to very fine grained sandstone; scattered layers of yellowish-orange to brown siderite(?) cement in very fine grained sandstone and siltstone. Carbon flecks and fragments throughout. Sharp, irregular contact with below. Upward coarsening interval capped by root zone; interval analogous to lignite-capped packages above. Depositional Unit 2 1256.5-1263.6 Claystone grading down to mudstone grading down to claystone. Yellowish-olive-gray (7.1) grading down to medium-gray grading down to very dark gray showing brown overtones. Abundant slickensided fractures in claystone. Abundant siderite spherules from 1260.3 to 1261.2 ft (identification confirmed by x-ray diffraction). Sparse carbon flecks and frag-ments, most abundant near base. Sharp, irregular contact with below. 1263.6-1264.6 Lignite. Black to brownish-black. Locally clayey. Thin-laminated. Sparse slickensided (1.0) fractures. Sharp, wavy, inclined contact with below. Forms lignite capped depositional package with upward coarsening interval below. 1264.6-1272.7 Sandstone. Dusky-brown grading down to pale-grayish-yellow-brown and pale-yellowish- (8.1) gray. Very fine to fine-grained, well-sorted. Indistinct crinkly laminae in top 0.4 ft.; mostly contorted and bioturbated laminae below; scarce low-angle laminae; scattered to abundant silty shale laminae; "lenticular" bedding in clay-rich lower 2 ft. Skolithos, Aren-icolites(?), Planolites(?), and indeterminate trace fossils. Scattered carbon flecks and frag-ments; most carbonaceous in shaly laminae; scarce mica flakes. Sharp, irregular contact with below. Depositional Unit 1 1272.7-1281.8 Mudstone. Yellowish-gray grading down to medium-light-gray and dark-brownish-gray. (9.1) Silt content increases downward as color darkens; sandy at base. Crinkly thin laminae in basal 0.2 to 0.3 ft; abundant slickensided fractures in clay-rich parts. Abundant siderite spherules from 1273.0 to 1278.0 ft (identification confirmed by x-ray diffraction). Abun-dant carbonaceous matter and carbon flecks and fragments in sandy base. Sharp, inclined, erosional contact with below. 1281.8-1283.0 Sandstone. Purplish-brownish-gray grading down to brownish-gray. Very fine to fine- (1.2) grained; moderate sorting; abundant interstitial clay. Contorted lenticular laminae; contor-ted, discontinuous to lenticular shale laminae. Bioturbated. Abundant carbonaceous matter in top 0.4 ft, less abundant below. Contact with below not preserved, probably sharp. Forms upward coarsening interval in combination with below. 1283.0-1286.5 Sandstone grading down to mudstone and silty shale. Very light gray grading down to (3.5) yellowish-gray grading down to brownish-gray. Sandstone very fine grained. Contorted bedding in upper part; no obvious bedding in lower part except for shaly laminae at base of unit. Fragments of interlaminated siltstone and shale enclosed in sandstone. Abundant quartz overgrowths in top 1 ft of sandstone; abundant siderite spherules from 1284.0 to 1286.3 ft. Deformed, 2-cm-long rip-up clasts of sandstone below in basal Dakota mudstone and shale. Base Dakota Formation. Sharp, wavy contact with below. Erosional sequence boundary. PURGATOIRE FORMATION "Upper Purgatoire Interval" (142.1) Depositional Unit 9 1286.5-1287.4 Interlaminated sandstone and shale. Very pale orange to pale-brownish-gray. Sandstone (0.9) very fine to fine-grained. Wavy and lenticular laminae, some contorted; scarce load casts. Bioturbated, chiefly Planolites-like burrows. Abundant interlaminated shale, brownish-gray above grading down to medium-dark-gray at base. Interlaminated shale near top of unit takes on color of overlying Dakota Formation clay rocks. Grades into below by alternation. Forms depositional package with below. 1287.4-1312.2 Shale. Medium-dark-gray grading down into medium-gray showing olive overtones. Thin- (24.8) laminated; laminae inclined 5o; sparse laminae of ripple-laminated, very fine-grained sandstone near top and base; sparse sand-filled burrows. Scarce carbon flecks, carbonized plant debris, and mica flakes. Scarce slickensided fractures. Sharp, wavy contact with below. Transgressive surface. Depositional Unit 8 1312.2-1312.3 Bentonite. Yellowish-gray. Plastic. Irregular, partly interlaminated contact with below. (0.1) 1312.3-1333.3 Sandstone and siltstone grading down to shale. Grayish-yellow-brown to light- and dark- (21.0) gray. Very fine grained to silt-sized; abundant interstitial clay. Sandstone and siltstone mostly bioturbated; wavy and lenticular laminae; contorted laminae; scarce oscillation-ripple structures; basal 1.3 ft dominated by thin-laminated shale. Abundant interlaminated medium-dark-gray shale; becomes shaly at base. Most burrows subhorizontal, Planolites-like; also Teichichnus(?) and indeterminate burrows. Scarce carbon flecks and mica flakes. Upward coarsening interval. Sharp contact with below. Transgressive surface. Depositional Unit 7 1333.3-1351.8 Sandstone grading down to interbedded sandstone and shale. Medium-light-gray grading (18.5) down to very light gray intercalated with medium-dark-gray. Very fine to medium-grained, poorly sorted; grain size generally decreases downward except for medium-grained sandstone in basal 0.1 ft. Wavy, lenticular, contorted, and bioturbated laminae; shale interbeds £0.2 ft thick more abundant downward, plastic when wet; similar to shale below. Trace fossils: Planolites, Terebellina, Teichichnus(?), and indeterminate burrows. Abundant interstitial clay; common shale chips £2 mm in diameter; scarce glauconite and mica flakes. Sparse quartz overgrowths. Sharp, wavy contact with below. Upward coarsen-ing interval. Depositional Unit 6 1351.8-1421.3 Shale. Medium-gray. Sparse silt grains. Thin-laminated, fissile; scattered laminae and (69.5) thin laminae of very fine to fine-grained sandstone and siltstone; laminae disrupted by subhorizontal burrows; 0.2-ft coquinoid shell bed on 0.1-ft cone-in-cone layer at 1415 ft. Inoceramus impressions and rare ammonites from 1406.5 to 1412.9 ft. Shale plastic when wet. Locally abundant pyrite or marcasite along sandstone and siltstone laminae; abundant pyrite or marcasite cement in shell bed. Scarce carbon flecks and mica flakes. Grades sharply into below. Forms depositional package with next below. Maximum Flooding Interval. 1421.3-1422.9 Sandstone. Very light gray to yellowish-gray. Fine- to medium-grained, moderate sorting. (1.6) Mainly bioturbated lenticular and contorted laminae; small-scale trough cross-laminae in sets 0.1 to 0.2 ft thick. Abundant interlaminated medium-gray shale. Trace fossils: Teich-ichnus(?), Planolites(?), Asterosoma(?). Abundant quartz overgrowths; local pyrite or mar-casite cement where bioturbated. Abundant shale chips, scarce mica flakes. Sharp, wavy contact with below. Depositional Unit 5 1422.9-1428.6 Shale. Medium-gray. Thin-laminated, fissile; scattered contorted laminae and lenses of (5.7) fine- to medium-grained sandstone similar to above; burrow casts mark base of sandstone laminae and lenses. Light-gray bentonite bed 0.3 ft thick at 1424.6. Pyrite or marcasite blebs and nodules, mainly in bentonite and sandstone lenses. Sharp, wavy to irregular contac t with next below marked by distinct upward decrease in abundance of mottled sandstone. Transgressive surface. Base "upper Purgatoire interval." "Lower Purgatoire Interval" (58.9) Depositional Unit 4 1428.6-1459.3 Sandstone. Light-gray to yellowish-gray. Dominantly fine-grained, sparse medium grains, (30.7) moderately well sorted. Discontinuous, contorted laminae , abundant contorted medium-dark-gray shale laminae throughout but especially in top 1.5 ft. >90% bioturbated; trace fossils: Teichichnus(?), Asterosoma(?), Terebellina(?). Light-gray bentonite bed 0.2 ft thick at 1458.2 ft. Friable; moderate quartz overgrowths; common pyrite specks, blebs, nodules <2 cm long. Abundant interstitial clay; common carbon flecks and fragments; sparse mica flakes. Sharp, wavy contact with below; transgressive contact. Depositional Unit 3 1459.3-1480.6 Shale. Medium-gray. Thin-laminated, fissile; contains beds of dominantly fine-grained (21.3) sandstone £1.2 ft thick similar to sandstone above; sparse ripple laminae in sandstone; shale chips common; also scattered sandstone laminae. Trace fossils include Astero-soma(?), Teichichnus(?), Planolites(?), and Skolithos(?) in sandstone beds; scattered sand-stone laminae marked by Planolites(?) burrows that increase in abundance downward. Quartz overgrowths in sandstone; calcite cement where sandstone is very light gray; abundant pyrite or marcasite blebs. Locally abundant interstitial clay. Light-gray bentonite bed 0.3 ft thick at 1424.6. Shale plastic when wet. Sharp, irregular contact with below. Transgressive surface. Depositional Unit 2 1480.6-1487.3 Sandstone. Light-gray and light-olive-gray showing dark-olive and very light gray mottles (6.7) £ 2 cm long. Medium-grained; well sorted; medium- to coarse-grained and conglomeratic in friable basal 0.3 ft. Bedding indistinct to wavy, crinkly, and inclined; local low- to high-angle trough cross-laminae in sets £0.5 ft thick; contorted to wavy dark-gray shale lami-nae. Scarce Skolithos burrows near top. 0.7-ft thick bed of thin-laminated, medium-gray shale from 1481.8 to 1482.5 ft; shale plastic when wet. Abundant quartz overgrowths; cal-cite cement in light-gray mottles; organic stain(?) in dark-olive mottles. Scattered carbon fragments £4 cm long; shale fragments; olive-gray to brownish-gray clay-rock fragments perhaps reworked from Morrison Formation. Conglomeratic base contains light-gray silt-stone fragments, scarce chert pebbles, quartz granules. Contact with below not preserved, but probably sharp and erosional. Possible transgressive surface. Depositional Unit 1 1487.3-1487.5 Shale. Medium-dark-gray, brownish overtones. Thin-laminated; scarce laminae of fine- (0.2) grained sandstone showing Planolites-like burrows, starved current-ripple structures. Shale plastic when wet. Contact with below not preserved because of washing of upper-most Morrison marl during coring, but probably sharp. Base Purgatoire Formation, base Cretaceous System. Transgressive surface and sequence boundary. MORRISON FORMATION Top Jurassic System (62.6 ft described) 1487.5-1512.2 Limestone (marl). Greenish-gray in weathered top 0.6 ft; light-gray grading down to light- (24.7) olive-gray and brownish-gray below. Micritic and clayey. Laminated to thin-laminated; also contorted and crinkled laminae; scattered thin clay laminae, mainly near top and base of unit. Oval to elongate burrow mottling; 1-3 mm cores of crystalline calcite in many mottles. Limestone rip-up clasts; shaly fragments locally. Scarce minute pyrite crystals; peculiar speckled texture of very light gray to white on gray background, speckles 1 to 3 mm in long diameter. Top 0.6 ft weathered and punky. Sharp contact with below despite gradational change in color. 1512.2-1517.0 Claystone. Greenish-gray grading down to moderate-greenish-gray showing grayish-red (4.8) mottles. No obvious bedding; slickensided fractures. Scattered ostracods. Weakly calcare-ous; minute pyrite crystals. Grades into below. 1517.0-1520.8 Claystone. Moderate-greenish-gray grading down to purplish-gray. No obvious bedding, (3.8) but horizontal streaking of colors in middle and lower parts. Slickensided fractures coated with "limonite." Scarce black nodules 3 mm in long dimension. Grades sharply into below. 1520.8-1526.7 Claystone. Greenish-gray and moderate-greenish-gray. No obvious bedding. Slickensided (5.9) fractures coated with brown "limonite" and purple hematite. Calcareous above, noncal-careous below. Sharp wavy contact with below. 1526.7-1528.1 Limestone (marl). Pale-olive-gray alternating with very light gray. Micritic and clayey. (1.4) Crinkly and thin laminae; clay partings. Grades into below partly by increase in clay con-tent and partly by alternation. 1528.1-1533.4 Mudstone and siltstone. Yellowish-gray and pale-brown. Indistinct contorted to crinkly (5.3) beds and laminae; laminae distinct near base; bedding controlled by variations in silt and CaCO3 content. Gradational contact with below. 1533.4-1550.1 Mudstone and siltstone. Light- to medium-gray showing green overtones grading down to (16.7) light-olive-gray. No obvious bedding to thin bedded and contorted shaly laminae; bedding controlled by variations in silt, CaCO3, and chert content; sparse laminae of very light gray siltstone to very fine to fine-grained sandstone near base of unit; lenticular and ripple laminae in sandstone. Abundant gray to purplish-gray and bluish-gray to orange-pink chert or chalcedony as irregular nodules £0.3 ft across and as impregnations; chert be-comes intergrown with clear and orange selenite down core in zones £0.5 ft thick. Vuggy porosity in some chert and gypsum intervals. Late Jurassic spores identified in sample from 1539.3 ft by E.J. Kidson and R.W. Hedlund. Morrison Formation continues to 1629 ft log depth; not described; repetitions of rock types described above, but dominantly pale-brown to light-brown siltstone and sandstone. Overlies Permian Taloga Formation.