THE GEOLOGICAL SKETCH,
Which I have drawn, does not make any pretensions to a geological map, which even a more able geologist than I am could not give in the short time and haste, in which I travelled through that country, but it may elucidate and concentrate at least what little information I have acquired in relation to that object. To make it more intelligible, I will add yet a short summary of the various geological observations # spread over the whole extent of the journal.
Independence, near the western frontier of the State of Missouri, is situated in the great Missouri coal basin, which occupies more than one-third of that State.
The first rock in situ which I saw in the prairie, after leaving Independence, was on Rock creek, (about 79 miles from Independence.) It was a yellow-brownish compact limestone, with encrinites, and similar fossils of the carboniferous limestone, as found in Missouri.
On Pleasant Valley creek (125 miles) the bluffs are formed by two different limestones: the one is white and compact; the other grayish, soft, and argillaceous. The first contained some indistinct fossils, but in too imperfect a state to determine what formation they indicate.
In Council grove (143 miles) a horizontal, grayish, argillaceous limestone prevails, without fossils.
Leaving Cottonwood creek (185 miles,) irregular heaps of bog-ore are seen" in the prairie, and a ferruginous sandstone of yellow, brown, and blue color, extends from here to Pawnee fork, (a distance of about 100 miles.).
The bluffs of the Little Arkansas consisted of a spotted, yellow, calcareous sandstone, and isolated pieces of ferruginous sandstone.
Between Camp Osage (the first camp near the Arkansas river) and Walnut creek, (263 miles,) I met with a very porous and scoriaceous rock in situ, apparently the product of action of subterranean fires upon t lie ferruginous sandstone. Most likely a large coal-field lying beneath here has become ignited, and produced this change of the rock. The so-called Pawnee rock (between Walnut creek and Ash creek) consists of the same ferruginous sandstone, changed by fire. On Pawnee fork (292 miles) I saw the last of it; the ferruginous sandstone there was more compact, and deep red.
On a branch of Big Coon creek (332 miles) I found the bluffs to consist of common standstone below, and a white, fine-grained marl above it. This marl resembles very much some from the cretaceous formation of the Upper Missouri; but finding no fossils, I could not ascertain it.
Two miles beyond that place (341 from Independence,) I had the first chance to examine the bluffs on the Arkansas; it was a grayish,conglomerated limestone, with a few small fossils, that were rather imperfect, but seemed to belong to the cretaceous formation. The neighborhood of the above mentioned marl raises this presumption nearly to certainty. I have, therefore, not hesitated to lay it down as cretaceous fornation. About 20 miles higher up on the Arkansas, I saw, upon a second examination, but a coarse conglomerate of sand and limestone. At the usual fording place (373 miles!) where I left the Arkansas for the Cimarron, no rocks were in situ.
