The Niobrara in Kansas differs from the same deposit in Southern Nebraska and on Niobrara river. This difference is seen in the physical features, but more particularly in the fossils. In Kansas it has more of the composition of clear chalky deposit. In its fossils it gives us a richer and more varied type of vertebrates. Thus far, no Pterodactyls have been found outside of the Kansas line.* In Saurian genera the Nebraska deposits have given less in quantity, and also less in generic and specific varieties than Kansas. This difference begins before we reach the State line, in Jewell and Smith counties, as we did not find a single Pterodactyl bone, or Bird bone, and very few of the Saurian, within twenty miles of the Nebraska boundary.
* Since this was written, a small specimen has been found by my young friend. S. W. Williston, of Manhattan, in the Jurassic beds of Wyoming. It is described by Marsh in the Am. Jour. Sci., Sept., 1878, p. 233.
The northwestern boundary** can be seen by reference to our geological map. The southeastern has not been so definitely traced. It is quite indistinct near the Nebraska line, being covered by the Tertiary, except in some ravines. It appears on the higher grounds in the southern part of Smith county, and then crosses the western part of Osborne, Ellis and Rush counties, and can be seen on Walnut and Pawnee creeks, when it disappears. Along this line it is usually found on the hilltops, The Niobrara is very unlike the Benton. The two divisions differ in a marked degree, both in the character of the fossils and in physical appearance. The 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. It is well defined in the tributaries of this river, nearly to the high divide between it and the Arkansas Valley. It is but poorly represented on Walnut and Pawnee creeks, in Ness and Hodgeman counties; and on the slopes toward the Arkansas river it is seldom seen, and then almost devoid of its characteristic fossils. It also loses most of its physical and fossiliferous features before it enters Colorado, west and south of Fort Wallace, and soon after entering that State, entirely disappears. 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 it did not prove substantial. The whiter portions are almost pure carbonate of lime, and can not be distinguished from the best specimens of foreign chalk. Prof. Dana, in the last edition of his Manual of Geology, says there is no chalk in North America except in Western Kansas.
** This boundary, given on p. 111 of the Rep. of 1875, included the Ft. Hays group, which I now separate.
G. E. Patrick, Professor of Chemistry in the Kansas State 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 shape-less particles. The Rhizopod 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 analyses, the figures given below. No. 1 was a fine specimen of snowy whiteness; No. 2 had a little yellowish tinge, and was as poor a sample as I could select.
| No. 1. | No. 2. | ||
| Moisture | .34 | .58 | |
| Insoluble in acids, (silica, lime and alumina) | .69 | 11.40 | |
| Alumina, (little oxide of iron) | .43 | .97 | |
| Ferrous carbonate | .14 | 2.83 | |
| 100.07 | 99.87 | " |
This chalk is manufactured near Trego, in Trego county, into whiting and shipped to Colorado and other markets. It produces a nice article, equal to that made from the best foreign chalk. It is found at various strata, in seams 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 higher strata were the most impure, being intermingled with sand and other coarse ingredients. Sometimes we found thin layers of flint, from half an inch to two inches in thickness. Occasionally these layers were, in part, covered with a thin coating of chalcedony. The later strata have been deposited not far from a shore line subject to currents. Sometimes may be seen marked oblique deposits, but very limited in extent, either vertically or horizontally. These were always varied in color and material. Layers of white chalk, with impure ones of various shades of buff, extended to a thickness of six to ten feet, and gave a neat, ribboned appearance. These layers were usually from one-fourth to one-half an inch in thickness, but frequently much thinner. In one instance I counted thirty-five in a thickness of little less than two inches, the white lines being nearly pure chalk, and the buff containing some fine sand. The fineness of material and the distinctness of each line indicate a slow deposit at a distance from the shores of the old Cretaceous lands.
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 Prof. 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. These seams are found in all parts of the Niobrara, though more common in the shales than in the chalk strata. When not crystallized the spar is harder than usual - apparently not quite as pure. In all cases, however, it will furnish good quick-lime, and for that purpose is more convenient than the chalk, as it does not crumble and yield so readily to atmospheric influences after burning. The seams were formed by fissures or rents in the original strata, made probably during their upheaval from the ocean level, and the lime was deposited on both sides of the cavity, and usually united in the center, but sometimes the middle is lined by most beautiful crystals of calc-spar. The seams being firmer than the chalk, stand like dikes, two or three feet above the surface, not vertically, but inclined 10° or 20° from a perpendicular. 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 8 1/4 lbs.
The darker shales also sometimes contain numerous small lenticular nodules of pyrites, frequently in fine crystals of various shades of brown.
This Niobrara is from seventy-five feet thick in Trego and Ellis counties, to two hundred feet in Rooks county. The fossils are scattered very similarly in all this thickness; some localities will furnish more from the chalk, while others will give more from the shales. We hunt for fossils in all alike, and on the whole with equal success.
The ravines of the Niobrara exhibit many features in common with the cañons of the Bad Lands of Dakota and Nebraska, but on a smaller scale. When a firm layer of chalky limestone overlies others of a softer texture, a narrow groove will be cut through the top, and then the wear goes on rapidly down to the level of the lower grounds. Frequently such cañons are one hundred feet long, fifteen or twenty feet deep, and but two feet across the top, being wider below than above. These occur near each other, and then the ravines become quite labyrinthine; an intricate place for hunters or Indians to hide. When these partitions between the cañons become detached from the hillside, and divided into sections, they stand as isolated columns. Such are the well-known "Monument Rocks," of the Smoky Hill Valley, in Gove county, and the "Castle Rocks," of Ellis county. The former stand as detached pillars, twenty to fifty feet high, in the valley, at quite a distance from the nearest hill. (See Fig. III.) To give a true idea of the monumental feature, several views should have been taken. Our figure includes a view of about one-half of the monuments. At "Castle Rock," near the extreme western angle, a pillar, sixty or seventy feet high and only twenty feet through the base, stands like a detached bastion two hundred feet from the Castle. The top is limestone, then chalk, while the base is firm, blue shale. The valley around is perfectly level. At the eastern end of the Castle, several smaller pillars seem to stand as outposts in that direction. The top or the Castle overlooking all, is covered by ten feet of Pliocene sandstone.
Fig. III. MONUMENT ROCKS, (Gove County, near K. P. R. R., looking northwest).
(From a sketch by S. W. Williston.)
The writer regrets that these fanciful rocks have not been photographed, so that twenty years hence, other photographs might show the rate of abrasion. Rain, frosts, and the hands of ruthless men, are destroying many of these unique pinnacles. They are thirty miles from the railroad, with no settlements near.
