94 ANNALS NEW YORK ACADEMY OF SCIENCES 



one point ou the Dyer ranch it has a thickness of only 10 ft., while a few 

 miles southeast it reaches a thickness of 125 ft. The sandstone composing 

 the layer is of nearly uniform color and texture. Its induration is only mod- 

 erate, and it weathers into many grotesque forms. Cross-bedding is well ex- 

 hibited by it in many localities. 



"17. Purple to greenish-colored clay 60 ft. 



"This is apparently an unfossiliferous layer, except in the uppermost hori- 

 zon, where species of dinosaurs belonging to the genera Brontosaurus and 

 Morosaurus occur. 



"18. Sandstone, grayish to light brown 10 ft. to 20 ft. 



"The above sandstone presents some very interesting stratigraphic phe- 

 nomena. It has, at the base, a layer of conglomerate about 2y2 ft. thick. 

 The conglomerate is composed of small silicious and argillaceous pebbles, and 

 is not very coherent. Something like two feet of sandstone rests upon the 

 conglomerate ; the bedding planes of the sandstone are oblique to the bedding 

 planes of the beds above and below. Succeeding the sandstone above is 6 

 in. of sandstones in very thin layers, with lignitic seams along its horizontal 

 but wavy bedding planes. The above is overlain by 4 in. of conglomerate, 

 followed by 1 in. of sandstone with oblique bedding planes. Overlying this 

 layer is a thin layer of sandstone in which the bedding planes are horizontal. 

 The remainder of the stratum is made up of sandstone with the bedding 

 planes as follows : One ft. oblique ; then 3 in. horizontal ; then 2 ft. oblique ; 

 and finally 3 in. horizontal. The stratum furnished in one place the trunk of 

 a large fossil tree and a large number of fossil cycads. Fragments of fossil 

 wood were found in a number of places, but cycads in only the one. Frag- 

 ments of a hollow-boned dinosaur were found in one place in the horizon. 



"19. Drab-colored clay 30 ft. to 40 ft. 



"This stratum contains the bones of the large dinosaur, Brontosaurus. 

 Otherwise it appears to be quite unfossiliferous. 



"20. Fissile, brownish sandstone 4 ft. to 5 ft. 



"No fossils wei'e found in this sandstone, and the most characteristic feature 

 about it is its uniformly brown color. It seems to be moderately persistent, 

 as its occurrence in many places in the hills was noticed. 



"21. Bluish-green clay containing very small concretions 30 ft. 



"In the bone quarries of this horizon, which furnished species of Bronto- 

 saurus, Morosaurus, and Diplodocus, were found specimens of {PlanorMs) 

 veternus and Valvata leei. This is the lowest horizon at which any of these 

 non-marine invertebrates were noticed. It is probable that they will be found 

 lower down, as the dinosaurs occur much lower. 



"22. Brown to bluish-gray arenaceous limestone ; 8 in. to 1 ft. 



"This stratum contains the following non-marine invertebrate forms : Unio 

 Jcnighti, U. daileyi, Valvata leei, and (PlanorMs) veternus. Species from the 

 same genera have been described by Meek from a similar stratum of limestone 

 in the Black Hilis. As these occupy much the same stratigraphical position 

 they are probably the same age. The Lioplacodes seem to be identical with 

 that described by Meek in the Geology of the Upper Missouri. 



