7. Shaly chalk, like ll, but surficially stained black to bluish gray, lenticular soft chalky limestone body in upper one-half caps low pedestal on one stream spur; FOSSILS - Inoceramus platinus?, Ostrea congesta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4 6. Limonite and gypsum, dark-yellowish-orange, central part pale yellowish orange with local masses of limonite up to 0.2 foot thick and 1.5 feet across and lenses of marcasite where section is fresh; unit is probably weathered bentonite . . . . . . . . . . . . . . . . . . . . . . . . . . 0.13 5. Shaly chalk, olive-gray to dark-yellowish-brown stained pale orange, tough, laminated, speckled, weathers soft and flaky; seams of gypsum along bedding and low-dipping joints . . . . . . . . . . . . . . . . 1.1 4. Limonite and gypsum, dark-yellowish-orange and nearly white, respectively, gypsum powdery, unit contains oblate spheroidal limonite masses; unit is probably weathered bentonite . . . . . . . . . . . . . . . . . . . . 0.09 3. Shaly chalk, light-olive-gray to yellowish-gray, weathering dark yellowish orange to grayish orange, soft, laminated, speckled, somewhat flaky, with small very thin lens of gilsonite? in upper part; FOSSILS - Inoceramus platinus?, Ostrea congesta . . . . . . . . . . . . . . . . . . . . . 7.65 2. Limonite and gypsum seam, dark-yellowish-orange, gypsum coarsely crystal- line, unit pinches and swells . . . . . . . . . . . . . . . . . . . . 0.06-0.1 1. Shaly chalk, medium-olive-gray with dark-yellowish-orange stain where weathered, tough, laminated, speckled . . . . . . . . . . . . . . . 2.3 Thickness of exposed part of Smoky Hill Chalk Member . . . . . . . . . 67.5 Total thickness of measured section . . . . . . . . . . . . . . . . . . 67.5 Description of Section Measured at STOP 8 NIOBRARA CHALK Smoky Hill Chalk Member Feet 32. Shaly chalk and chalky limestone, highly oxidized, pale-yellowish-gray to very light gray, brittle and massive beds alternating with softer, tough, shaly beds, all speckled; shaly part poorly laminated, weathers flaky; two limonite partings may be weathered bentonite seams; FOSSILS - Inoceramus platinus, Ostrea congesta, fish scales . . . . . . . . 10.2 31. Bentonite, yellowish-gray, unit composed mostly of limonite and jaro- site, forms deep re-entrant . . . . . . . . . . . . . . . . . . . . . 0.06 30. Chalky limestone, cap rock in cliffs and pinnacles, weathered color ranges from very pale orange and light gray to grayish orange with some nearly white beds near top; higher parts of unit blackened by lichens; rock relatively brittle, speckled, obscurely laminated, all but upper- most 4.4 feet more or less massive; generally cavernous, weathering with 6-foot-thick zone of especially conspicuous cavernous hollows lying approximately 5 to 11 feet below top; FOSSILS - Inoceramus platinus, Ostrea congesta, burrow? structure . . . . . . . . . . . . . . . . 15.8 29. Chalk, weathered, wide range of pale coloration from very light gray to pale yellowish orange, tough, poorly and obscurely laminated, speckled, appears massive at distance but contains many seams of selenite lying parallel to bedding and marked locally by limonite-jarosite nodules; upper part of unit locally weathers cavernous; FOSSILS - Inoceramus platinus, Ostrea congesta, fish remains . . . . . . . . . . . . . 13.6 28. Bentonite and gypsum, dark-yellowish-orange, limonitic, seam consists mostly of selenite . . . . . . . . . . . . . . . . . . . . . . . . . 0.02 27. Chalk, weathered, mottled very light gray and very pale orange with five more or less continuous seams of selenite; very tough, obscurely laminated, speckled, weathers soft and flaky . . . . . . . . . . . . . . . . . 0.9 62