The beautiful Vermilion Cliffs and the White Cliffs of southern Utah which together form the walls of Zion Canyon, the red sandstone out of which is carved Rainbow Natural Bridge, and the jagged Echo Cliffs seen to the northeast of Desert View (Navajo) Point at Grand Canyon are all monuments of the Jurassic Age. These high walls are of sandstone—formed from sand steeply piled at varying angles. They have been aptly called “cliffs of fossil sand dunes.”
While desert winds and a burning sun were playing a prominent part in the Grand Canyon region, during the Jurassic Age, other sections of the country were favored with a moist climate and luxuriant vegetation. Dinosaurs and other reptiles waded about in swamps and developed to tremendous sizes. The country teemed with life, very different from that of today, yet none the less interesting.
FROM SEASHELLS TO COAL BEDS
(DAKOTA. MANCOS, MESA VERDE; CRETACEOUS PERIOD)
CRETACEOUS SHELLS FROM SOUTHERN UTAH
During the last part of the “Age of Dinosaurs,” in that period of history known as the Cretaceous, much of northeastern Arizona, southern Utah, and northwestern New Mexico apparently was submerged beneath a sea. Mollusks abounded, and various other types of water animals swam or crawled in this region. Their shells were buried and preserved among the muds and limes which were accumulating, and today many of them are found in the rocks of this age.
As time went on, the Cretaceous seas were expelled from their basins in the Southwest. Low-lying coastal plains—two hundred and more miles wide—with luxuriant vegetation and perhaps swamps, replaced them, and these new conditions were the means of much coal formation. Great accumulations of vegetable matter, buried beneath sediments brought down by streams, eventually formed the many layers of coal which today are found in various places in Utah, Arizona, and New Mexico. In the last named state some extensive and valuable coal beds are found in rocks of this age near Gallup. Impressions of leaves and pieces of fossil wood are also numerous among these rocks and they indicate that there was a warm, moist climate during that period in which they grew.
The Cretaceous Period ended with a general change of conditions or a revolution, the world over. Many of the seas were changed into lands, new mountains were formed and the dinosaurs and giant reptiles were largely replaced by mammals and other modern varieties of life.
COAL CANYON. PAINTED DESERT COUNTRY AERIAL PHOTO COPYRIGHT FRED HARVEY