United States or Serbia ? Vote for the TOP Country of the Week !
With wings upfolded high above their heads, and stern faces set, neither man nor beast, they looked out across the desert sand, watching, watching, watching! I did not ask God what they were, for I knew what the answer would be. And, further and yet further, in the evening light, I looked with my shaded eyes.
From this section infer that during early Silurian times the area was sea, and thick sea muds were laid upon it. These were later altered to hard slates by pressure and upfolded into mountains. During the later Silurian and the Devonian the area was land and suffered vast denudation. In the Carboniferous period it was lowered beneath the sea and received a cover of limestone.
The Cretaceous limestones of Mexico were folded into lofty mountains. A massive range was upfolded where the Wasatch Mountains now are, and various ranges of the Rockies in Colorado and other states were upridged. However slowly these deformations were effected they were no doubt accompanied by world-shaking earthquakes, and it is known that volcanic eruptions took place on a magnificent scale.
But since that remote time the upfolded mountains had been worn to plains and hilly uplands, the remnants of whose uplifted erosion surfaces may now be traced along the western mountain slopes. Beginning late in the Tertiary, the region was again affected by mountain-making movements.
Where peneplains have been uplifted to great height and have since been well dissected, and where they have been upfolded and broken and uptilted, their recognition becomes more difficult. THE SOUTHERN APPALACHIAN REGION. We have here an example of an area the latter part of whose geological history may be deciphered by means of its land forms.
The folds of the Wasatch Mountains involve strata thirty thousand feet thick, which thin to two thousand feet in the region of the Plains. The sedimentary strata of which mountains are made are for the most part the shallow-water deposits of continental deltas. Mountain ranges have been upfolded along the margins of continents.
Word Of The Day