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branches and leaves of conifers heaped in a confused mass, and deformed by a 

 too advanced stage of decomposition. These shales are immediately below 

 the under layers of the upper group, No. 2, which they resemble by 

 their color and the presence of scales of fishes. However, they still have 

 the essential characters of the Dakota group, viz, dicotyledonous leaves. 

 Among others, I found there an entire leaf of the same species of Laurus, 

 which is common from Minnesota to Kansas, in the whole thickness of the 

 formation, and the only sjiecies seen in the bed of quartzite in the Blackbird 

 Hills. From this we may conclude that the whole group bears, with scarcely 

 any change in the nature and compound of its strata, the same essential char- 

 acter, or its peculiar vegetable remains, from the lowest strata to the line of 

 conjunction with the Fort Benton group above it. 



For a time, as remarked before, the clay-beds, which had been observed 

 mostly at the base of the Dakota group, were considered, without paleonto- 

 logical evidence however, as representing either the Jurassic or the Triassic 

 formation. This supposition was derived from the idea of a sequence of the 

 geological formations, as they are generally admitted, and, of course, it seemed 

 at first incredible that formations like the Triassic and the Jurassic, which 

 have immense development in Europe, should be without any trace of repre- 

 sentatives over the coal-measures of the West. The subject has been satis- 

 factorily discussed, and little evidence can be added to what has been pub- 

 lished already. There was still, however, some uncertainty in regard to the 

 geological reference of the clay-beds at the base of the Dakota group, which, 

 overlying the Permian, are locally of a tolerable thickness, and where, as yet, 

 no fossil remains, either animal or vegetable, had been found. This lowest 

 member is marked by Professor Swallow as especially predominant in the 

 vicinity of Smoky Hill River, Cottonwood, and Fancy Creek, where it is com- 

 posed of brown, drab, and reddish marls and shale 32 feet thick. I had an 

 opportunity to see these clay-beds exposed at many places along the Smoky 

 Hill River, and unexpectedly found in them a peculiar kind of remains which 

 give positive evidence of their Cretaceous age. The essential exposure where 

 the discovery was made is at the bottom of a small branch of the river, about 

 fifteen miles southeast of Fort Harker, where a layer of coal, or rather of carbon- 

 aceous matter, 1 to 2 inches thick, crops out, interlaid into a bank of soft, black, 

 laminated shale. The traces of coal in the creek have stimulated a searching 

 for some thick bed of the same matter in that locality, and one shaft has been. 



