Paleontology and geology

Precambrian rocks in Arizona record at least three sequences of deposition, metamorphism, and erosion. Sediments were deposited, buried, turned to rock, and altered by heat and pressure. Then some of the rocks were eroded, and new sediments were laid down. By the Late Precambrian, shallow marine conditions prevailed throughout the state. The limestones formed from this time contain fossil evidence of stromatolites.