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Show 214 IIr.- CRETACEOUS SYSTEM. 1.- NIOBRARA. 2.- DAKOTA. The Cretaceous in Kausas covers an area of over forty thousand square miles, or more than half of the surface of the State. The Pierre and Fox Hill groups of Hayden, and all equivalents of those periods, are entirely wanting. The Benton group also appears to be absent. The Cretaceous is, therefore, represented in Kansas by the Niobrara and Dakota only. The line of demarkation between the Pliocene and Cretaceous is well defined and sharp. Adjoining the Permian easterly, it is not so clear; yet soma recent examinations, made in company with Prof. O. St. John, show that the boundary is not difficult to trace. We have never been able to find any fossils of the Jurassic or Triassic, the beds of the Cretaceous resting conformably or nearly so on the Permian. That portion south of the Arkansas Biver has been little examined, either by myself or others, but appears to be represented by the Fort Hays and Dakota groups. 1.- NIOBRARA. a.- Niobrara. b.- Fort Hays. The Niobrara, or its equivalents in time, is well represented. It is divided into two clearly- defined portions, by a massive bed of limestone or yellow chalk, which when fully exposed, where it has not suffered from abrasion, is 60 feet in thickness. It is seen in the valley of the Smoky, southwest of Fort Hays, as well as seven miles west of that place, and at various points to the northeast, crossing the Solomon just above the Forks, near Osborne City, and entering Nebraska in Republican Valley, near where that river crosses the State line. It is composed of layers of yellow chalky limestone, from 1 to 3 feet in thickness. It makes an excellent building- material, working easily, yet sufficiently compact to be used for stores or dwellings. At Hays, the school- house and court- house are built from it; and ten miles west of that place the Kansas Pacific Bailway has opened a quarry for supplying stone for use along its line. It also burns to a good quicklime. The massiveness and persistence of this stratum make it a well- defined geological horizon. Below this line, as well as in it, vertebrate* fossils are few, while above it they are numerous and of varied type. Its fossils are Inocerami, fragments of Haploscapha^ Ostrea, with occasional remains of fish and Saurians. The vertebrates are always so rare that we never wasted our time in bunting them in this stratum; still our largest Saurian, Brimosaurus of Leidy, was found in it in Jewell County. a.- Xiobrara proper. The Niobrara in Kansas differs from the same deposit on Niobrara Biver. The upper portion, which we shall call Niobrara proper, or simply Niobrara, is very unlike the lower, which shades imperceptibly into deposits like the Benton. The two divisions differ in a very marked |
