The american southwest might have once been more like the Tibetan Plateau. Researchers have been looking for the reason why the earths crust in the american southwest is so thick, and why there are such large deposits of copper. Usually the crust is thickened by movement of the techtonic plates coming together and over lapping. It is not thought that there enough fault lines in the southwest to cause this. Thick crusts are also associated with large copper deposits like are found in the south west. Looking at pictures of the Tibetan Plateau it looks vast and barren, I can imagine Arizona looking like this at one time. The high deserts of Arizona have a similar quality. Although the high deserts of arizona get cold I'm not sure they are as cold as Tibet. Southwestern U.S. was once similar to today's Tibetan Plateau: Study. (2019, December 5). Retrieved from http://www.sci-news.com/geology/arizona-plateau-07874.html .