The Eleodes of Riley County, Kansas

Abstract

is fully twelve miles in width. It seems probable that the latter-mentioned streams formerly flowed through to the master stream of the valley near Stanberry. At Falls City, Neb., on the Big Nemaha, there is a terrace about forty feet above the level of the stream composed mainly of older rocks, capped with a few feet of gravel, which is mostly chert. This material is observed along other streams in Kansas as marking the bottom of preglacial streams. Taking the slope from Falls City to Stanberry, it is found to be about five and one-third feet per mile. While the facts just considered seem to favor the theory as presented, there are some facts which do not readily harmonize. One is the fact that the pressure in artesian wells at Tarkio cannot be from a higher portion. of the main channel, because they are about on the same level with the bottom lands near Nebraska City, so that the water appearing at Tarkio cannot be supplied from the main channel of the Missouri, as we might expect. It seems probable that the water in the Tarkio wells is supplied by an old channel or tributary coming in from the north along the line of the Big Tarkio. Moreover, the slope of the valley from Nebraska City to Tarkio seems insufficient, but we should remember that we are trying to judge of the slope of the stream from the altitude of the bedrock on the bottom, which may vary from being parallel with the surface of the stream at least thirty or forty feet. It should be mentioned that at Atchison there is distinct trace of an old channel running toward the northeast and showing several feet of chert gravel about seventy feet higher than the Missouri river. That would indicate that it was probably another tributary of the Platte-Grand river, which is at that altitude because of the divide of the master stream northeast and the Kansas river to the south. While the tracing of this ancient channel is more of educational than of economic importance, it may eventually lead to the discovery of an important water supply.