| OCR Text |
Show 45 as on the northerly flank of the Paradox anticline (see pi. 3) and are locally called "parks" or "basins," such as Long Park or Saucer Basin, Flat areas above cliffs along canyons are usually known as "benches," but few such features have a local name. Geology The sedimentary beds in Southwestern Colorado range' from late Paleozoic to Upper Cretaceous in age. They are described as follows: (See pi. 4 also.) Upper Cretaceous Dakota sandstone £~200 feet A gray to brown sandstone, conglomeratic in places. Cliff-forming and capping many mesas. Upper Jurassic Morrison formation + 625 feet The upper member 4-350 feet thick, locally termed "Brushy Basin," is composed of variegated shale and thin beds of sandstone and limestone. It forms gray to greenish-gray slopes. The lower member + 275 feet thick, locally termed "Salt Wash7" i s composed of sandstone interbedded with a red and gray shale. The sandstone beds are the ore-bearing formations and form a series of cliffs separated by shale slopes. Summervllle formation ±75 feet Thin-bedded red and white sandstone and shale; forms typical shale slopes but seldom is well exposed. |
