Keith Meldahl, a geologist and professor of geology, has written one of the most interesting books on the history of the American West I’ve ever encountered. It’s a history of how it got the way it is, physically. He covers the creation of California – it’s only recently been pasted onto North America – how the Sierra Nevada formed and what it actually is, why Nevada looks like it does, how the Colorado Plateau got there, how the Rocky Mountains were formed, and some very interesting and odd details as well. Along the way, he provides a few vignettes of the early explorers and settlers and their often brutal encounters with these features.
Probably the two most important players in all this are something you’ve never heard of, the Farallon Plate, and the North America continent itself. Long story short, 240 million years ago the world’s landmasses had merged together into single massive conglomeration called Pangea (All Land). Prior to that time, North America had moved West to East, the East coast was the active margin and the West coast, which then ended in a line from Wyoming across Utah and through Nevada, trailed along. The eventual impact with Africa raised the Appalachians to Himalaya scale and merged us to it like India to Asia. By 150 million years ago, Pangea was breaking apart and a newly born mid-ocean ridge opened the Atlantic Ocean for the first time. As the ridge continued to build new seafloor, it spread apart. Everything east of that ridge began being pushed to the east, and everything west of it, including North America, began being pushed to the west. It was then that things began changing for the western states. You can page through that 100 million years at Arcadia Street for a glimpse at the plant and animal life you would have seen, had you been there.