The Permian Basin of West Texas has been a testing ground for numerous geologic concepts about both the surface and the subsurface. Deepwater Permian clastics, which infill the Midland and Delaware basins, are significant reservoirs, estimated to contain more than 10 billion barrels of oil in place. Outcrops in the arid Guadalupe and Delaware mountains provide excellent exposures that can be compared to the subsurface. Geologists use these exposures as analogs for subsurface models in the Gulf of Mexico and North Sea.

The Permian Brushy Canyon Formation, one of the clastic units, is superbly exposed over a fairway 25 miles long and 7 miles wide, with more than 1,000 feet of vertical exposure. The arid climate and the canyons that dissect the terrain provide a three-dimensional view of both the resistant and nonresistant strata, sand/silt ratios, and the depositional mechanisms that operated from the basin margin outward into the basin. Proximal deposits are highly channelized with a net/gross ratio of 25-30 percent; the distal net/gross ratio is nearer to 60-70 percent. Channel geometries and high-energy depositional mechanisms are visible 15-20 miles into the basin before planar bedforms become predominant. This photo essay illustrates these processes, from which it is possible to discuss their applications to other areas.

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