The Permian Reef Trail features an exposed fossil reef from the Permian period about 280 million years ago. Unfortunately the total 3 miles to the top of the reef was not reached during the hike. However, the trail still served as a perfect example of the ecology and geological succession of the reef during the Permian period.
At the beginning of the trail, there is a riverbed evident from rounded pebbles and gravel that indicate transportation conditions. Conglomerates in the area from cemented together limestone fragments are also present. It is apparent that the deposits were transported and deposited at the base of the reef slopes during flash floods because the riverbed contains deposits that vary in size but are well rounded.
Next further up the trail, Lamar limestone, a thin layered dark limestone due to a high composition of petroleum begins to surface. The Lamar limestone is micritic and very-fine grained and some of them contain orange chert nodules (Fig.1). The Lamar limestone formed from organic materials sinking to the deep bottom of the ancient Permian Ocean (National park Service). According to Dunham's classification scheme and based on the mud matrix and grain ratio, the Lamar limestone can be classified as a wackestone and is part of the Bell Canyon Formation. Additionally near the second stop, there are wackestones with fossils present (Fig 2).
The next stop displayed bioturbated packstone.
Karren features and chemical weathering are seen on pillars on the trail.
Towards the top of the reef, the presence of fossils becomes more prominent such as the appearance of brachiopods, sponges, crinoids, cephalopods, horn corals, pelecypods, and fusulinids (Fig. 3).
Figure 1. Lamar limestone with orange chert nodules.
Figure 2. Wackestone with fossil (Crinoid).
Figure 3. displays the various fossils seen on the Permian Reef Trail (A) Fusulinids (B & C) Bivalve (D) species of marine mollusc (E) Crinoid
References
National Park Service. Listening to the Rocks: A Young Person's Guide to the Permian Reef Trail.