The country south-west of the Missouri, between the Konzas and the Platte, is drained principally by Wolf river and the Great Nemahaw. These rivers, like the Nodowa and Nishnebottona, which enter the Missouri nearly opposite them from the north-east, rise in the prairies at an elevation probably of forty or fifty feet above the level of the Missouri. As they descend, their vallies becoming gradually wider, embosom a few trees, and at length, near their entrance into the Missouri valley, are forests of considerable extent. The surface of these prairies presents a constant succession of small rounded hills, becoming larger and more abrupt as you approach the beds of the rivers. The soil is deep, reposing usually on horizontal beds of argillaceous sandstone, and secondary limestone. In all the limestones along the Missouri, we observe a tendency to crystalline structure, and they have often a reddish or yellowish white {130} colour. There is, however, always something in the arrangement and in the aspect of the crystals to distinguish these sparry varieties from the primitive granular limestone, to which they have something of general resemblance. The horizontal disposition of the strata of this limestone, the great numbers of organic relics contained in it, and its intimate connexion with coal strata, indicate with sufficient clearness its relation to the secondary rocks. No person who shall examine this stratum with the least attention, either about the Nemahaw and the Konzas, or in the mining district at the sources of the Gasconade, the Merameg, and the St. Francis, will for a moment mistake it for any of those varieties of transition or primitive limestone, which it in some respects so closely resembles. The crystalline varieties, no less than the compact blue limestones, embrace numerous masses of chert or hornstone. This occurs of various colours, and these are arranged in spots or stripes. Some specimens have several distinct colours arranged in zigzag lines, somewhat resembling the fortification agate. The hunters use fragments of this stone for gun-flints; the savages also formerly employed it in the manufacture of arrow points and other implements.[160]