area was part of Indian reservations and therefore off-limits to non-Native Americans, the Wichita Mountains were rumored to contain rich gold deposits. When the area was first opened up for settlement, many prospectors staked mining claims, and towns were laid out to serve the presumed bonanzas, but no economic deposits were found. The gold boom was prolonged by some unscrupulous assayers who found gold in every sample, but the miners eventually gave up, leaving behind ghost towns such as Wildman, Oklahoma. Geology Overview The Wichita Mountains are rocky promontories and rounded hills made of red and black igneous rocks, light-colored sedimentary rocks, and boulder conglomerates. The Wichita Mountains were formed in four distinct geologic episodes following a failed continental rift. Magmatism induced by continental rifting just prior to and in the Cambrian Period produced the granites and rhyolites (the red rocks), gabbroic rocks, anorthosites, and diabases (the black rocks). Subsidence resulted in burial by sandstones and carbonates (the light-colored rocks) during the early Paleozoic. Uplift during the Pennsylvanian Ouachita Orogeny brought these rocks to the surface as mountains. Weathering and erosion during the Permian Period flattened the mountains and produced a mantle of conglomerates. The mountains themselves are Permian landforms covered and preserved by river-borne sediments in the Permian and partially excavated only in recent geological times. Exposure of these fossil mountains is greatest towards the southeast; much of the western part of the Permian range remains buried under sandstones and mudstones. Details The geologic history of the region began with the deposition of late Precambrian to early Cambrian sandstones collectively known as the Tillman metasedimentary group. These sediments were intruded by a coarse mafic layered complex as the region began to rift apart during breakup of the Neoproterozoic continent, Pannotia. The exposed portion of this unit, named the Glen Mountains Layered Complex, consists of gabbro, anorthosite and troctolite. Recent high-precision dating yields an age of 532.49 ± 0.15 Ma. These are the dark gray rocks found throughout the Raggedy Mountains, the central lowlands region of the wildlife refuge, and to the immediate north of the refuge. Uplift and erosion followed, as the layered complex is unconformably overlain by the extensive lava flows of the Carlton Rhyolite Group. The rhyolites are a brown-red to orange porphyritic rock with 5–10 mm orange-colored alkali feldspar crystals. Most of the rounded hills on Fort Sill are made of this rhyolite, including Medicine Bluffs.