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Show 215 degree both in the character of the fossils and in physical appearance. This Niobrara occupies a belt of the country next adjoining the Pliocene, about thirty miles in width in the northern part of the State, but gradually widening to more than twice that extent in the Smoky Hill Valley. At the latter district, it extends from the western line of Ellis County to the Colorado boundary. It is composed of chalk and chalky shales. The former is of various shades of color from buff to pure white, and is seldom sufficiently hard to be used as a building- material. Some of the buildings at Fort Wallace were constructed of it, but did not prove substantial. The whiter portions are almost pure carbonate of lime, and cannot be distinguished from the best specimens of foreign chalk. Professor Dana, in the last edition of his Manual of Geology, p, 4J5, says there is no chalk in North America except in Western Kansas. G. E. Patrick, professor of chemistry in the Kansas University, has published, in the Transactions of the Kansas Academy of Science, an article on this chalk, from which we extract the following remarks, with his analyses: Examined under the microscope, it appears perfectly amorphous- a simple aggregation of shapeless particles. The KUizopod shells, which almost universally occur in the chalk of the Old World, sometimes comprising nearly its entire substance, seem to be quite wanting in our Kansas chalk. With a good microscope, and a high power, I have been unable to detect a trace of them. The amount of impurity varies, of course, in different samples of the chalk, but in no specimens that I have seen does this amount exceed 15 or 16 per cent. Two samples yielded, upon analysis, the figures given below. No. 1 was a nne specimen of soovy whiteness; No. 2 had a little yellowish tinge, and was as poor a sample as I could select. No. l. No. 9. Moisture... 34 .58 Insoluble in acids ( silica, lime, and alumina) 69 11.40 Alamina ( little oxide of iron) 43 .97 Ferrous carbonate 14 2.83 Calcium carbonate 19080.. 4077 9894.. 9179 This chalk is found at various strata, in thickness varying from one to eight feet. It differs in purity and other features, in the same stratum, in different localities. Unlike the European chalk, it never contains flint nodules. The shales of this division contain lime mingled with clay and sand in varying proportions. They are harder than the chalk, requiring the pick in extricating the fossils. They are of all shades of slate- color, sometimes bleaching on exposure to the weather. Near Fort Wallace, some strata are so much like the Benton in Nebraska, that Professor Hayden, on a hasty inspection, mistook them for a portion of that group. ( Final Report on Nebraska, p. 68.) These shales, in some localities, are traversed by seams, from one to six inches in thickness, of firm, pure calc- spar, usually in flat crystals. Inclosed in these seams are small crystals of barite. At Sheridan, Wallace County, we find the latter spar in the dark shales. One beautiful crystal, of a rich amber- color, weighed eight and one- fourth pounds. The darker shales also sometimes contain numerous small lenticular nodules of pyrites, frequently in fine crystals. This Niobrara is from 75 feet in Trego and Ellis Counties to 200 feet in Books County. The fossils are scattered very similarly in all this thickness; some localities will furnish more from the chalk, while others * ill give more from the shales. We hunt for fossils in all alike, and on the whole with equal success. |