[1] It preserves fossils dating back to the Guadalupian Epoch of the Permian Period.

[1] The formation becomes more dominantly carbonate rock near the Guadalupe Reef and the beds become thicker.

[2] The formation is interpreted as shallow marine sediments deposited on the San Andres platform, which flanked the Delaware and Midland Basins.

The interbedded carbonate rocks and sandstone reflect fluctuations in sea level.

Kelley subsequently adjusted the definition of the lower contact of the formation, in 1971.