Arizona, a major source of copper in the world, has rocks as old as two billon years, which is much older than the state’s landscape.
“Thirty million years ago, we would see a big mountain range, maybe as high as a part of (the) Andes, running from Las Vegas through Tucson toward El Paso,” said Jon Spencer, Ph.D., a senior geologist at the Arizona Geological Survey. “That topography is now reversed (because) that whole mountain range was basically pulled apart into pieces to produce the Basin and Range Province.”
And, geology of Arizona is far more complicated than it might seem.
“There has been a long history of fault movements, igneous activity, so much that it takes a lot of work to figure out what is actually happened to the rocks,” he said. “Western and southern parts of the state have been repeatedly disrupted...whereas the Colorado Plateau has been fairly stabled...for about billions of years.”
The University of Arizona has actually played a large role in studying the geology of Arizona.
It contributed in understanding three key elements, such as porphyry copper deposit, crustal extension, and the origin of major river systems, particularly in the Colorado River, Spencer explained.
And, if you want to see a bit on Arizona's complex geology, you take a look at this excerpt from 'Under Arizona', produced by Eight, Arizona PBS in Phoenix.