The spectacular Middle Permian outcrops of the Guadalupe and Delaware mountains have been studied for over 100 years, with intensive research following the realization that they expose the subsurface strata of the Permian Basin Petroleum Province. However, the less imposing Patterson Hills have largely been ignored. The Patterson Hills are a set of north northwest-south southeast trending hills that lie about 2 miles to the southwest of Guadalupe Peak and El Capitan. The topographically expressed Patterson Hills extend approximately 7 miles from northwest to southeast, and are approximately 3.5 miles wide perpendicular to the trend of the hills. They are composed of fault blocks antithetic to the main boundary fault at the western escarpment the Guadalupe Mountains, and contain the same succession of strata as the larger range. The same strata also make up fault blocks just to the east that are not expressed as hills, but comprise relatively flat topography that underlies the Williams Ranch road and the alluvial apron between the Pattersons and Guadalupes.
To the north and west the Patterson Hills mostly expose reefal Capitan facies, but to the south and east they provide outcrops of the basinal Delaware Mountain Group facies. These strata were last studied closely by King (1948), and include several important fossil localities such as the locus typicus of the late Guadalupian ammonoid Strigogoniatites fountaini.
This presentation will focus on three interesting insights provided by sections in the Patterson Hills. One focus will be on a Delaware Mountain Group section that is almost entirely composed of carbonates, lacking the characteristic siliciclastics that dominate the section elsewhere. This section exposes the equivalent of the South Wells to the Rader members beneath the Capitan Formation. Another focus will be on numerous outcrops of the latest Guadalupian Reef Trail Member, although King did not recognize his “post-Lamar” strata in the Patterson Hills. The Lamar-Reef Trail-Castile succession is widely exposed in southern parts of the outcrop area, with important biostratigraphic implications from recognizing the complete section. The third focus will present a refined perspective on the timing of progradation by the Capitan Reef over basinal deposits, and the resulting suggestions about the geometry of the northern Delaware Basin margin and consequences for basin infill.