Page:Popular Science Monthly Volume 15.djvu/323

 Probably the final conclusion reached in the discussion of the origin of granites, to which Mr. King has certainly contributed many new and interesting facts, will be that each of the causes, heat and pressure, should be credited with a share of the effects produced.

—One of the most interesting and surprising results of Mr. King's exploration is the discovery of a section of stratified and unmetamorphosed strata said to be conformable throughout, reaching from the base of the Cambrian to the top of the Carboniferous, and attaining a maximum thickness of 32,000 feet. No section of the Palæozoic rocks of equal magnitude has yet been discovered elsewhere in the world, and the announcement will doubtless be received with some incredulity by geologists, but the accuracy with which the measurements were taken by Mr. King and his assistants, and the vindication of his classification afforded by the fossils, which were carefully reviewed by Mr. Meek, Professor Hall, and Mr. Whitfield, seem to leave no room for doubt. This great group of rocks is said, as before stated, to have been laid down in a basin bounded on the east by the ranges of the Rocky Mountains in Colorado, and on the west by a broad archæan area in Nevada. In the middle rose the lofty islands of the Wahsatch, which toward the west presented an abrupt slope of 30,000 feet, against which the Palæozoic rocks abutted. From the inclosed character of this sea most of the sediments formed in it are mechanical, and represent the wash from the adjacent land, but in the middle of the section occurs what Mr. King calls the Wahsatch limestone (Lower Carboniferous and Upper Devonian), seven thousand feet in thickness. Although no certain measure of time is afforded by the mechanical sediments—since the rapidity with which they were deposited may have varied indefinitely with the activity of eroding agents—this great limestone mass, formed as it must have been through organic agencies, represents a lapse of time which is almost beyond the reach of the imagination; and if, as Mr. King states, the Palæozoic series is essentially conformable throughout the area it occupies, we have here evidence of a stability in the physical conditions of this portion of the earth's surface, which, so far as known, is without parallel.

Mr. King gives two sections of the Palæozoic series taken, one in the Wahsatch Mountains and the other in Middle Nevada, which differ only in minor details. The Wahsatch section is, however, the most complete, as it shows the base of the Cambrian system, which is not visible farther west; it is as follows: