About 525million years ago, when northern Arizona was at the bottom of a shallow sea, a thin layer of sediment called the Tapeats Sandstone was deposited over the Cleopatra tuff. Limestones and other sediments accumulated above the sandstone until about 70million years ago when the Laramide Orogeny created new mountains and new faults in the region. One of these faults, the Verde Fault, runs directly under Jerome along the Jerome anticline. Crustal stretching beginning about 15million years ago created Basin and Range topography in central and southern Arizona, caused volcanic activity near Jerome, and induced movement along the Verde Fault. This movement exposed the tip of the United Verde ore body at one place on Cleopatra Hill and moved the UVX ore body to below the surface. Basalt, laid down between 15 and 10million years ago, covers the surface beneath the UVX headframes and Jerome State Historic Park. The basalt, the top layer of the Hickey Formation, caps layers of sedimentary rock.
