The copper deposits of the Clifton-Morenci district, Arizona

The oldest rocks of the Clifton quadrangle are pre-Cambrian granite and quartzitic schists, separated by an important unconformity from the covering Paleozoic strata. The latter comprise a total thickness of 1,500 feet. At the base lie 200 feet of probably Cambrian quartzitic sandstone, succeeded by 200 to 400 feet of Ordovician limestones. About 100 feet of Devonian (?) shale and argillaceous limestones cover the Ordovician beds, while the uppermost part of the Paleozoic sediments consists of heavy-bedded pure limestones of lower Carboniferous (Mississippian) age with a thickness of 180 feet.