You are looking out over the edges of tilted and eroded layers of sandstone and shale that lie upon much older rocks in the mountains behind you. If the eroded layers were restored to where you stand they would be more than two miles thick. The sandstone and shale were deposited as flat layers of sand and mud in streams, lakes and shallow seas during a time that began about 300 million years ago and ended about 70 million years ago. Later, the flat layers were bent upward during the rise of the Front Range of the Rocky Mountains. Since then, they have been eroded to their present form. The sandstone layers are hard, and their eroded edges form great ridges but the soft shale layers are hard, and their eroded edges from great ridges but the soft shale layers from valley which extend far to the north and south.
The rock on which you stand, and in which the Red Rocks Theater is carved, belong to the Fountain Formation. In places, these rocks contain fossil remains of tiny animals that lived in the sea about 300 million years ago (fossil 1).
Alon the highway that crosses the ridge in front of you there are maroon and gray shales of the Morrison Formation. These rocks - - about 130 million years old - - have yielded the remains of the largest dinosaurs that ever lived (fossil 2).
The ridge, known as the Dakota Hogback, is composed of hard Dakota sandstone, which lies above the Morrison Formation. The Dakota sandstone contains fossil clams (fossil 3) and is a valuable source of artesian water and of oil in the plains region east of the hogback. Afew miles south of here it contains uranium.
Mount Carbon, farther east, has seams of coal but consists mainly of clay used for bricks. It also contains fossil seashells and dinosaur bones about 100 million years old (fossils 4 and 5).
After these deposits were laid down, volcanic debris, partly preserved at Green Mountain, was deposited by streams.
Gravel along the creeks was washed down during the ice age only a few thousand years ago, when mammoths (fossil 6) roamed the Denver Plains.