"Geologic time" Quotes from Famous Books
 ... degradation, the north-and-south cliffs are, in the main, though not always, escarpments of displacement. Let us understand what this means. Over the entire region limestones, shales, and sandstones were deposited through long periods of geologic time to the thickness of many thousands of feet; then the country was upheaved and tilted toward the north; but the Colorado River was flowing when the tilting commenced, and the upheaval was very slow, so that the river cleared away the obstruction to its channel as fast as it was presented, ...
— Canyons of the Colorado • J. W. Powell |
