The Goat Seep Dolomite, which immediately underlies the Capitan Limestone, constitutes the lower third of the Guadalupian shelf-margin interval and formed the first large, high-angle, reef-like carbonate unit in the Permian Reef Complex of West Texas and New Mexico. The Goat Seep Dolomite and the Capitan Limestone are similar in that both consist predominantly of inclined strata deposited on a high-relief shelf margin with a steep edge of 25° to 30°, and both can be divided into three similar facies: a shelf-edge or reef facies, a high-angle foreslope, and a low-angle toe-of-slope facies. Shelf-to-basin relief ranged from about 250 m at the beginning of Goat Seep time to 600 m at the end of Capitan time (Fig. 1). The dominant fossils in both are sponges. However, the Goat Seep is not simply an older Capitan, but differs significantly in aspects of morphology, mineralogy, fossils, and cements. Compared to the Capitan, the Goat Seep (1) is largely dolomite; whereas, the Capitan is primarily limestone; (2) has a much thinner to absent shelf-edge or "massive" facies; (3) contains little or no skeletal boundstone, algae, or the problematic organism Tubiphytes, which are common in much of the Capitan (particularly the Upper Capitan); and (4) contains less coarse-fibrous and interparticle cement, interpreted to have an early marine origin.

The major similarities and differences between the Goat Seep and the Capitan formations are discussed below and are summarized in Figure 2. Most of the information on the Capitan comes from the work of Babcock (1974, 1977) and Yurewicz (1976, 1977). Data on the Goat Seep are largely from Crawford (1981).