The Grand Canyon Of Arizona: How To See It By George Wharton James






































































































































 -  Where has
it all gone?

Naturally an answer to these questions is mere conjecture, as only from a
study of - Page 34
The Grand Canyon Of Arizona: How To See It By George Wharton James - Page 34 of 85 - First - Home

Enter page number    Previous Next

Number of Words to Display Per Page: 250 500 1000

Save Money On Flights

Where Has It All Gone?"

Naturally an answer to these questions is mere conjecture, as only from a study of the facts revealed underneath the present strata, can any comparative knowledge be gained of the conditions existent at that prehistoric age.

There may have been one river, or a score, or any number between, and it is probable one or more rivers carried the Algonkian debris westward and deposited it, as the Colorado River (not brought into existence until centuries later) is now doing with the debris of the existent strata.

Another Subsidence. Now, a new era is about to dawn. Planed and smoothed off as they are, the Algonkian and Archaean masses are to be submerged once more in the ever receptive ocean. A period of subsidence occurs, and the whole area is soon hidden under the face of the sea. But, all around these are masses, some day to be mountain peaks, that refuse to sink again into the sea. Then the forces of the air assail them. If they cannot be drowned, they shall be gnawed at, smitten, cut and worried by the air, the chemicals of the atmosphere, the storms, the rain, the hail, the frost, the snow, and thus made to feel their insignificance. Slowly or rapidly, they yielded to this disintegrating process, and as the rocky masses broke up, they were washed by the rills and streams into the bed of the sea, where they soon rested upon the tilted ends of the Algonkian strata and exposed surfaces of the Archaean masses, waiting for them.

The Deposition of the Tonto Sandstones. The wise men tell us that this ocean was a salt sea, and that it was quite shallow while these new sediments were being deposited. Little by little one thousand feet of the sediments of this epoch were washed down, so that it is very likely that the tilted strata upon which they rested slowly sank lower and lower to accommodate them. Then, for some reason or other, there was a rest for a while - a few hundreds or thousands of years - and the masses of sediments became cemented into sandstone and shale, which we call the Cambrian formation, or the Tonto sandstone. This is to be seen resting both upon the Archaean and Algonkian from the porches of El Tovar. It is composed of strata of dull buff, very different from the brilliant reds - almost crimsons - of the Algonkian, and the bright reds of the strata which later were to rest above them.

Geological Terms. What an audacious science this geology is! How ruthlessly it wrests aside the curtain from the mystery of the past, and how glibly it deals with thousands, millions of years, tying them up into packages, as it were, and handing them out labeled "eras" and "periods." As usual, the names made by the wise men are hard to pronounce, and seemingly hard to understand. But a few minutes will take away the difficulty. They divide the eras into four, viz.: 1, Proterozoic; 2, Paleozoic; 3, Mesozoic; 4, Cenozoic. All these "zoics" have to do with life. Proterozoic means before life, and signifies the rocks that contain no fossils indicative of life; Paleozoic signifies the most ancient forms of life; Mesozoic signifies "middle life" or those between the most ancient and the Cenozoic, or recent forms of life. The periods are lesser divisions of the eras. In the Proterozoic, there are two periods, viz.: the Archaean and the Algonkian. The Paleozoic has six periods, viz.: the Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian. The Mesozoic era has three periods, the Triassic, Jurassic and Cretaceous, while the Cenozoic era names five periods, - the Eocene, Oligocene, Miocene, Pliocene and Pleistocene.

Absence of Certain Strata. To shorten our story, let me at once say that during the periods that the Ordovician, the Silurian and the Devonian were forming, the Grand Canyon region was either above water so that it received none of these sediments, or, if any were deposited, they were almost entirely removed by the weathering processes before described, ere the region again sank into the ocean to receive the deposits of the Carboniferous epoch.

The Carboniferous. During this latter period, more than three thousand feet of strata were deposited. These are the most striking in appearance of all the Canyon strata, for they reach from the Tonto shales to the rim, and consist of three principal strata (with many smaller ones in between). The largest is the red-wall limestone, which constitutes the base of nearly all the architectural forms found in the Canyon, and is the thickest of all the strata. It presents the "tallest" wall of the series. The two separate walls, one above the other, on the top of the Canyon, as seen in the arms of the amphitheatre at El Tovar, are the other two wide members of this Carboniferous period. The lower is the cross-bedded sandstone, and the upper the cherty limestone. There is a remarkable difference in the appearance and the material of which these Carboniferous strata are formed, and those of the East and Europe. We generally think of coal-beds - carbon when this period is mentioned. Here there are none. In the East, in England, and in other parts of Europe, vast marshes existed in this period, and the rank vegetation of these marshy areas formed the coal-beds, with which the Carboniferous there abounds. It is only by the fossils found that the periods to which the various strata belong are determined, and the fossils, millions of which abound in the upper limestone, are clearly of the Carboniferous epoch.

As these strata and this period bring us to the "rim" of the Canyon, it might be easy to imagine that the processes of uplift and subsidence, and deposition of more strata, as far as the Canyon region is concerned, now cease. Such, however, is not the case.

Later Strata. As we go away from the Canyon, either north or east, we find thousands of feet more of the later depositions, and the geologists affirm that many of these at one time may have overlaid the Canyon region.

Enter page number   Previous Next
Page 34 of 85
Words from 33487 to 34514 of 85893


Previous 34 35 36 37 38 39 40 41 42 43 Next

More links: First 10 20 30 40 50 60 70 80 Last

Display Words Per Page: 250 500 1000

 
Africa (29)
Asia (27)
Europe (59)
North America (58)
Oceania (24)
South America (8)
 

List of Travel Books RSS Feeds

Africa Travel Books RSS Feed

Asia Travel Books RSS Feed

Europe Travel Books RSS Feed

North America Travel Books RSS Feed

Oceania Travel Books RSS Feed

South America Travel Books RSS Feed

Copyright © 2005 - 2012 Travel Guides