Utah Centennial County History Series - Grand County 1996

I n discussing the geologic history of the area, we have touched upon the great eras used to classify life on the planet: the Paleozoic, Mesozoic, and Cenozoic. Signifying Old, Middle, and Recent life, they are useful categories for specialists. What follows will be far from comprehensive. In fact, the information presented here is meant to promote awareness that we are not now, nor have any lifeforms ever been, alone upon the land. As we are bound to the land, it appears obvious to me that we are bound also to our fellow-travelers. It would be pleasant if the bond were one of mutual caring and respect; it is essential for our own well-being that it at least be acknowledged and not threatened too high-handedly.

The ancient oceans of the area harbored ancient forms of life, some of which were fossilized in the sedimentary rocks of the Paleozoic era. The fossils are usually of relatively simple sea creatures: shellfish and crustaceans. It is with the Mesozoic era that most people's attention sharpens. During this great span of time, organisms emerged from the seas and began to walk, crawl, or slither upon the land. Towards the end of the Paleozoic era, some 240-225 million