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The delicate and beautiful colors of Bryce are due to the white limestone which in many places retains its creamy color, but in others has been stained a vivid pink by the drainage from upland washes. The Canyon itself is almost entirely the result of running water which has carved and etched its pattern during geologically recent times. Just as the Grand Canyon and Zion Canyon were made possible by a great elevation of the land in this region, so also was Bryce affected. The small streams of the Paunsagunt Plateau were given power to cut into the sandstones and limestones which form the Pink Cliffs, and due to the peculiar nature of these rocks the many spires, promontories, and pinnacles were formed as remnants of erosion in the valleys.

A GREAT EROSION SURFACE
(CENOZOIC AGE)

The level, flat and almost featureless skyline of Grand Canyon is an outstanding characteristic of the plateau of northern Arizona. This surface is fascinating to some; monotonous to others. To all, it is one of the most striking features of the region. The history which it represents, moreover, is of extreme interest and impressive length. Here on the top of the great plateau is seen the result of vast erosion. Long periods of work by water, wind, and other elements have gradually worn away strata that were once above. Just as erosion is forming the Grand Canyon today, so it has accomplished this much greater task. Several thousand feet of materials have been removed from the surface over much of this entire region.

A GREAT EROSION SURFACE NATIONAL PARK SERVICE

South of Grand Canyon, at Red Butte, east in the Painted Desert, and north in Utah are found remnants of those rocks which once formed a continuous layer over the present plateau. Red sandstones and shales representing former sands and muds of shallow water and beach, pebble-rocks and marls deposited by rivers and containing the remains of cone-bearing trees, crocodiles, and dinosaurs—all these rocks and probably others once gave color to this area just as today they lend brilliance to the Painted Desert and to southern Utah. In those places high cliffs mark the lines of recession—the stages of the constant retreat of the rocks from the Grand Canyon region before ever-working forces of erosion. Red Butte to the south of Grand Canyon, on the other hand, has been preserved as an isolated remnant of the same rocks by its hard, resistant cap of lava. Thus we have mute evidence of a tremendously large and wonderful story of former lands, and of their later wearing away to leave the great plain which now forms the surface of the plateau about Grand Canyon.

CRUSTAL MOVEMENT AT GRAND CANYON
(CENOZOIC AGE)

Many visitors to the Grand Canyon are distinctly surprised when they find numerous seashells, corals, and sponges, beautifully preserved in the limestone layer upon which they are standing. The idea immediately occurs that this region was once beneath the sea. Obviously then either the land has risen or the ocean has receded.

A careful study of the region shows that the rock strata which form the great plateau of northern Arizona have been bent into a huge arch or dome. The Santa Fe railway travels steadily up grade to the south rim of Grand Canyon which is 7,000 feet above sea level. The north rim is a thousand feet higher, while fifteen miles farther north a high point of 9,000 feet is attained. In southern Utah the limestone layer which forms the top of Grand Canyon passes beneath the surface at 4,000 feet.