Rensselaer Union, Volume 8, Number 6, Rensselaer, Jasper County, 28 October 1875 — The Geological Importance or Oar Weston Explorations. [ARTICLE]

The Geological Importance or Oar Weston Explorations.

In no period of the world’s history has there been a greater activity displayed in enterprises to increase the knowledge of our globe and its history than at the preset dav; as instances of which may lie cited the explorations in Central Africa, those of the ruins of the cities of antiquity, such as Nineveh, the expeditions to the' north pole, intended for settling the mystery of an open polar sea, the deepsea soundings in the Pacific Ocean, proving the existence of a sunken continent, sum, last but not least, American explorations in the great West, now in progress, which have already contributed to our knowledge of geology facts of greater importance than any obtained during the previous half century. It is especially in the region of the Yellowstone River abounding as it does with hot springs ami geysers, and in the valley of the Colorado that the most instructive features have been discovered. While in the last few decides the importance and universality of Slow upheavals have been demonstrated, the explorations have shown that a second agent, namely, erosion, is of the utmost importance aud results in a variety of features, varying with the nature of the soil, the climate (wet, dry or rainless), presence or absence of winter frosts, etc. In Colorado the erosion by the rivers produces canons in the comparatively easily worn-out rock of thousands of feet in depth; while the aridity of the climate prevents the rain from destroying the results of the erosion, as is the case in countries where rainfall is of ordinary occurrence. It is evident, therefore, that the arid regions around the Colorado River give specially favorable opportunities for studying the effects of erosion, and the resent researches in that country have resalted in classification of these effects, as, 1, the erosion of water gaps; 2, the cliff erosion of canons; 8, hogback erosion, and 4, bill and mountain erosion. The second and third classes are due to the undermining action of water in arid climates; while in the first and last this action is modified by surface washings in rainy or moist climates.

When another topographical feature is added, namely, the eruption and outpouring of molten matter from below, its overflow covering the eroded lands, and its subsequent erosion in its turn, a new field of investigation is opened, especially instructive in arid climates, where surface washings do not destroy the prominent points of interest. This makes the region of the Colorado particularly rich in peculiar features, such as canons and canon valleys/volcanic caves and volcanic mountains, cliffs and hogbacks, buttes and plateaux, naked rocks and drifting sand, bluffs, valleys, etc. Ail the inount£‘n forms of tliis region are due to erosiou, “ing carved out by the running waters; but, notwithstanding the aridity of the climate in many localities, beds hundreds of feet in thickness and hundreds of thousands of square miles in extent, beds of schist, granite, limestone, sandstone, scale and. lava have slowly yielded to the unseen powers of the air, crumbled away into dust, and been washed away by the rivers. It is an illustration on a gigantic scale of the return of the lands to the ocean depths from xvhlch they once arSse. It appears, however, that the climate there has not always been so arid as it is now; SO the basin of the Great Salt Lake which is now so depressed that its waters have no outlet to the sea and are entirely disposed of by evaporation, leaving all dissolved matter behind, had once a moist climate aud so much rain that the valley was filled with water to its brim, forming a large and deep fresli-water lake which had its outlet into the Columbia River. Mr. G. K. Gilbert, who studied the features of this outlet, considers its epoch identi«cai with the glacial period; and from a further study of the deposited soils he has proved that before the glacial epoch an arid climate prevailed there of many times longer duration than the present epoch of 100,000 years which followed it. The period of time required to form successive deposits of thousands of feet iu thickness, which the erosion of the Colorado River has brought to light, in its deep canons, is enormous, and we cannot suppose that here the erosion was less than that of" other rivers, although in mpist climates the evidences of this erosion have been destroyed; while in the arid climates of our West they were preserved.

The evidences are that that region was lifted up from the ocean’s bosom three tunes; that three times the rocks were fractured; that three times the lava poured out of the crevasses, and that three times the waters carved out valleys iu their course seaward. The tlrst of these periods was after the formation of the granite rocks; the second succeeded the red sand’ stone formation; the third period is the present. The remnants of the first and second periods are buried; but we know that, unnumbered centuries ago in the past, the granites and schists, now on the bottom of the grand canon, were formed as a sedimentary bed beneath the sea; that then an upheaval took place, after whicn thousands of feet of beds were washed away in the sea by rains; then a depress sion took place, sinking the whole region some 20,000 teet beneath the ocean’s surface, and allowing the formation of sandstone, at least 10,000 feet iu thickness, as a sediment; then a second upheaval came, changing it again into dry land; then the rains washed away channels in the sandstone 10,000 feet deep, requiring countless years of gentle but unrelenting .energy. Again the sea rolled over the land, which became its bottom, and received a new deposit of more than 10,000 feet of rocky bed; and lastly, this ocean bed was again upheaved, and for 100,000 years the atmospheric influences and the running streams, gathered from the clouds in the highest mountain tops, have been making gorges, canons and valleys, and carrying the debrit back to the sea, from whose bottom the material all came. We ask: Will the sea, at some future Seriod, invade that land, by the sinking own of the latter, and will coral reefs be formed, and serve perhaps for the burial of the bones of the beings which shall then exist ? Will the surrounding continents or islands be washed into that sea and form new beds of rock, which, when again upheaved, will form a new land, and canons again be formed, and reveal in their walls, to another race of intelligent beings, some of the features of the time in ■Which we live ~at presents —Scientific American.