219 



At Wilsou's station, I saw the clialky liuiestoue of the Niobrara group filled with 

 Inoceramus problematicus. A part of the bed is in slaljs or thiunish layers, as it usually 

 appears wherever it occurs south of the Missouri River ; but a part also is more are- 

 naceous and rust-colored. Between the two hundred and forty-fifth and two hundred 

 and fiftieth milestone west, the road cuts through No. 3 (Niobrara) very distinctly, the 

 whole country appearing to be underlaid by this rock. 



As this deposit thus seen and described by Professor Hayden resfs 

 directly on the Dakota, and all those "which he supposed might possibly 

 be Benton, are clearly above tlie strata seen at Wilson's station, the 

 Benton is not seen in Kansas. The loTver portion of our Fort Hays may 

 be an equivalent of the upper portion of the Benton, though there does 

 not appear to be any line of demarkation, either by fossils or physical 

 structure. 



At Wilson's station and at other places in the same geological hori- 

 zon, to the thickness of 140 feet, it is composed of shales and thin layers 

 of limestone. The latter are filled quite largely with Jnocem»«<.s and 

 a few other marine shells, and occasionally ^vith fish-remains. The 

 shales are variable in color, hardness, and composition, lime and clay 

 predominating. This deposit is variable at the same horizon at different 

 points, containing no thick bed of limestone. To make a section at any 

 particular locality would be of little value unless half a dozen others 

 were made for comparison. 



The only persistent feature is a thin stratum of buff sandy limestone, 

 in the upper portion, never over 10 inches in thickness. It extends from 

 Smoky Hill Valley northeasterly into Kebraska. It contains I)iocera- 

 nius prohlematicus, Gryphea, Belemnife, and an Ammonite, all poorly pre- 

 served, and, excepting the first, too indistictfor si)ecific indeutification. 

 It is much used as a building-stone on the whole line named. It is soft, 

 fine-grained, and easily wrought, and its color is jileasing to the eye. 



In the Arkansas Yalley, west of Fort Dodge, the Fort Hays division 

 is represented by loose sandstone. Kext above this is the friable, 

 bluish-black, or slate-colored shade which lies immediately under the 

 massive limestone. It abounds in concretions, or septaria, of all sizes 

 from 1 inch to G feet in diameter. The body of the concretions is of 

 hard clay-marl with cracks lined with beautiful crystals of calc-spar. 

 These cracks frequently extend to the outside, and are then filled with 

 a light lime, which gives them fanciful markings, inducing several per- 

 sons to send small ones to me as " fossil turtles ". This stratum is well 

 exposed near the railroad, a few miles west of Fort Hays, and in most 

 places where the massive limestone lies on the high bluffs. It is about 

 60 feet in thickness, and frequently contains fine clusters of compound 

 crystals of selenite. It affords a few fish and saurian remains. It is 

 more noted, especially in the Saline and Solomon Valleys, for the num- 

 ber and variety of its Ammonites, embracing a dozen species, from 1 to 

 30 inches in diameter. The largest are always in fragments, but some 

 of the smallest are nearly perfect. Usually a portion of the bright 

 pearly shell is still to be seen. A species of Scnphites near larvaformis 

 is also found in the small concretions ; also several Inocerami^ one near 

 I. Nehrascencis of Owen. 



The physical features of this stratum, which are very uniform, are 

 similar to the Benton in Northern Nebraska, but its fossils are different. 



The total thickness of the Fort Hays group is 2G0 feet. 



The Dakota group includes all the Cretaceous east of the Xiobrara. 

 As no fossils of the Triassic or Jurassic have yet been discovered, after 

 ten years' search, we conclude that the Dakota rests directly on the 

 Permian. While the dividing-line has not usually been very well de- 

 fined, yet iu a few instances the fossils of the PermoCarboniferous and 



