HORN CORAL (NATURAL SIZE)
During the early stages of the period when these marine animals lived and multiplied in the region, a great body of salt water extended over its surface from far to the west, remained briefly, then retreated from the area. Soon, however, marine waters advanced once more and another sea was formed with its shoreline extending eastward even beyond the region in which we now find Grand Canyon. Evidences of the second and larger sea are found beyond Flagstaff to the south, in the Painted Desert to the east, and almost to Zion Canyon to the north.
The presence of corals and sharks’ teeth not only indicates that this region was covered on more than one occasion by marine waters, but also suggests that these seas were warm and shallow. This is estimated to have been some 200 million years ago.
FOSSIL SHARK’S TOOTH (NATURAL SIZE)
ROCKS OF THE FOURTH ERA
The Painted Desert and Zion Canyon Region
CHAPTER IV
THE MESOZOIC ERA
The Fourth Chapter of the earth’s history is commonly known as “the age of dinosaurs.” Large reptiles were the dominating forms of life all over the world during this age. Landscapes and types of climate varied considerably, and in the Grand Canyon region they changed completely several times. During some periods ocean bodies covered the country; at others desert winds piled up dunes on the surface. Again this region was the flood plain of rivers, where pebbles, mud and great logs of pine were washed in and deposited. At still other times coal was formed in some quantity. All of these interesting features of the Fourth Chapter will be briefly treated in the pages following. Their records as found at Zion Canyon to the north, in the Painted Desert to the east, and at the Petrified Forest to the south are such that a visitor to the region can scarcely help but marvel and wonder at their meaning.