22. Shale, medium-gray to medium-dark gray weathering to dark yellowish orange, quartz silty in lower part, sandy and thinly laminated in upper part; sand argillaceous, occurs in lenses and very thin layers; zone of alunite nodules in upper part; FOSSILS - Inoceramus ruther- fordi?, Ostrea beloiti, Borissiakoceras, Reophax and Hedbergella . . . 3.7 21. Siltstone, dark-yellowish-orange, discontinuous, quartzose, argillaceous, limonitic, thinly laminated to gently cross-laminated, friable. . . . . . . . . . . . . . . . . . . . . 0.2 20. Shale, medium-dark to light-olive-gray weathering medium brownish gray, silty, streaked with thin laminae and lenses of quartz silt or very fine sand, with specks of carbonaceous matter, soft, weathers flaky, streaked locally with limonite; bentonite is 0.08 foot thick; FOSSILS - Plesiacan- thoceras amphibolum, Borissiakoceras reesidei, Ostrea beloiti, Inoceramus sp., Reophax, Hedbergella, Ammobaculites, Trochammina . . . . . . . . . . . 12.7 19. Sandstone, light-olive-gray weathering moderate yellowish brown, quartzose, alternating well- and poorly cemented beds, softer layers argillaceous with several thin shale partings, with specks of carbonaceous matter, bentonite is 0.08 foot thick, light olive gray to greenish gray; FOSSILS - Inoceramus sp., Callistina lamarensis, fish remains . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7 18. Shale, similar to 20, in part limonite- and jarosite-stained; well- cemented sandstone, 0.1-foot-thick, light-olive-gray, thinly laminated, lies 7.5 feet above base; bentonite is 0.05 foot thick, light gray; FOSSILS - Callistina lamarensis, Inoceramus sp. (prisms), worm castings, Reophax, Ammobaculoides, Trochammina, Verneuilinoides, and Hedbergella (last two above sandstone bed only) . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3 Total thickness of Graneros Shale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.8 DAKOTA FORMATION 17. Sandstone, mostly weathered moderate yellowish brown, quartzose, mica- ceous, carbonaceous, limonitic, moderately well cemented, argillaceous in upper 1 foot, with numerous clay galls; FOSSILS - Callistina? sp. . . . . . . . . . . . . . . . 2.4 16. Sandstone and sandy shale; sandstone light olive gray weathering dark yellowish orange, quartzose, argillaceous, carbonaceous, friable, in part limonite cemented and very dusky red in color; shale medium dark grey, in part laminated; FOSSILS - worm? burrows . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 15. Shale, medium-dark-gray, quartz silty, soft, thinly laminated, inter- bedded in lower 0.8 foot with sandy carbonaceous shale and very thin beds of quartzose sandstone; interbedded in upper 0.8 foot with very thin layers of thinly laminated very fine quartz sand; FOSSILS - Trochammina, Ammobaculites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6 14. Siltstone, dark-gray to medium-light-gray, quartzose, argillaceous, sandy, carbonaceous, micaceous, soft, friable; FOSSILS - upright reed? molds in top 0.5 foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 13. Lignite, grading upward into carbonaceous silty shale, black to dark- grey. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 12. Shale, dark-olive-gray, silty, carbonaceous, irregularly streaked with light-olive-gray laminated quartzose siltstone; bedding depressed around numerous upright reed? molds; FOSSILS - reed? molds . . . . . . . . . . . . . . . . . . . . . 1.7 11. Siltstone, olive-gray to dark-olive-gray, quartzose, argillaceous, streaked with lighter colored quartz silt that occurs in part as highly contorted lenslike bodies; bentonite, 0.03-foot-thick, pale-yellowish-brown, at base; FOSSILS - upright reed? molds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 10. Lignite, brownish-black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.4 9. Shale, dark-olive-gray to dark-gray, slightly silty to very silty, weathers flaky; FOSSILS - reed? molds (some upright) . . . . . . . . . . . . . . . . . . . . . 1.7 8. Siltstone, yellowish-gray, well-cemented, quartzose, laminated to gently cross-laminated, iron-stained, in lensing beds, with dark-gray silty shale partings; FOSSILS - upright reed? molds, carbonized plant frag- ments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.4 49