Geology of the Late Paleozoic Horseshoe Atoll in West Texas

Abstract

Regional geology.-The Horseshoe atoll is a subsurface accumulation of fossiliferous limestone which is as much as 3,000 feet thick and which was deposited during Pennsylvanian and early Permian time in the northern part of the Midland basin, in western Texas. It is a horseshoeshaped mass about 90 miles across in an east-west direction and about 70 miles from north to south. The crest of the atoll is a series of irregular hills and depressions, and the flanks slope gently away to merge with a broad limestone platform on which the atoll rests. Large quantities of petroleum have been produced from reservoirs in the eastern and southern parts of the atoll.