Sharon Springs Shale Member.- The Sharon Springs Shale Member, the type section of which is at McAllaster Buttes, Stop 6, consists of a poorly exposed soft lower part and a well- exposed hard upper part. The lower part, which forms half or more of the member, is a dark- gray soft shale that contains ferruginous concretionary beds and a few thin layers of bentonite. Fossils are scarce; a few of the concretionary beds contain Baculites obtusus Meek and species of Inoceramus and Pteria. This part of the Sharon Springs will not be seen on this excursion. The upper part of the member, which crops out extensively at McAllaster Buttes, is a resis- tant, organic-rich, buttress-forming brownish-gray shale that contains hard limestone concre- tions, soft phosphatic concretions, and thin layers of bentonite. A bed of very large, closely spaced septarian limestone concretions is present in the upper part; these concretions contain thick veins of pale-brown calcite in which occur a few crystals of barite. Occurrences of fossils are rare in the upper part of the Sharon Springs although one concretion contained numerous Baculites asperiformis Meek. Weskan Shale Member.- The Weskan Shale Member consists of soft clayey shale that has numerous concretions and many beds of bentonite, some of which are 1/2 to 1 foot thick. The lower part contains thin ferruginous concretionary layers and small worm-burrowed phosphatic nodules. The upper part is characterized by many beds of light-gray, hard dense limestone concretions. Well-bedded lengthy limestone concretions mark the base of the member. Fossils found in the limestone concretions of the Weskan consist chiefly of species of Inoceramus, Pteria, and Anomia, and fragments of ammonites. Only the basal part of the Weskan can be seen at the McAllaster Buttes. Lake Creek Shale Member.- The Lake Creek Shale Member is a dark-gray flaky shale that has many thin concretionary ferruginous layers that impart a rusty appearance to the out- crops. Baculitids, chiefly B. reesidei Elias, are common but other fossils are scarce. Figure 6.- Photomicrographs of representative thin sections of Upper Cretaceous rocks of western Kansas. (1) Jarosite-cemented quartzose silty sandstone from near middle of Graneros Shale, southwestern Russell County. Crossed nicols, X75. (2) Skeletal limestone from near top of Graneros, central Russell County, showing dominance of Inoceramus prisms. Crossed nicols, X75. (3) Shaly chalk from lower part of Jetmore Chalk Member, Greenhorn Limestone, Stop 2, showing ellipsoidal pellet (near center of photograph), streaks of organic matter, and foraminifers. (4) Chalky limestone from middle part of Jetmore, Stop 2, showing foraminifers in matrix of microsparite. Plain light, X60. (5) Marly chalk from middle part of Fairport Chalk Member, Carlile Shale, southwestern Ellis County, showing spar-filled foraminifers and compressed pellets (gray ovoid bodies near center of photograph). Plane-polarized light, X150. (6) Shaly chalk from uppermost part of Fairport, showing compressed pellets (medium-gray bodies) and streaks of clay and pyrite. Plane-polarized light, X150. (7) Quart- zose silty sandstone from middle part of Codell, Stop 5. Crossed nicols, X60. (8) Chalky limestone from middle part of Fort Hays Limestone Member, Niobrara Chalk, Stop 9. Plain light, X60. Compare with photograph number 4. (9) Con- cretionary limestone from basal part of Weskan Shale Member, Pierre Shale, Stop 6, showing foraminifers, fish bone, and pyrite (black) in matrix of microsparite. Plain light, X60. 24