Geology of the Grand Canyon area

The geology of the Grand Canyon area includes one of the most complete and studied sequences of rock on Earth. Uplift of the region started about 75 million years ago during the Laramide orogeny. Volcanic activity deposited lava over the area 1. 8 million to 500,000 years ago. There are at least 14 known unconformities in the geologic record found in the...