Within the Grand Canyon region, the upper part of the Hermit Formation contains red and white, massive, calcareous sandstone and siltstone beds that exhibit low-angle cross-bedding.
[1] As summarized by McKee in 1982,[3] the sedimentary strata assigned to the Supai Group and Hermit Formation have a long and complicated nomenclature.
As defined by Darton, the Supai formation included all Pennsylvanian-Permian strata, mostly red beds, lying between the Redwall Limestone and the Coconino Sandstone in the Grand Canyon region.
[1] The Hermit Formation consists of a poorly exposed, slope-forming, heterogeneous assemblage of interbedded red-to-brown mudstone, siltstone, and very fine sandstone.
Near the base of the Hermit Formation at many localities within Grand Canyon and in the Sedona, Arizona areas, rare trough to planar-tabular sets of cross-stratified sandstone, fine-grained and well-sorted, with climbing translatent strata, occur.
[1] In parts of central and eastern Grand Canyon region, the lower contact of the Hermit Formation consists of paleovalleys of considerable depth cut into the Esplanade Sandstone.
[1][3] Throughout Grand Canyon and into the Aubrey Cliffs regions, the upper contact of the Hermit Formation with the overlying Coconino Sandstone is a sharp, flat, lithologic disconformity.
This is due to the unfavorable conditions of fossil preveration associated with the arid fluvial environments and grain size of the Hermit Formation.
Both are meganeurids, members of an extinct clade resembling modern dragonflies, and date the Hermit Formation to the early Permian Period.
[7] Other reported invertebrate fossils include a partial wing of an odonate and a forewing of an unnamed blattoid or cockroach.
Finally, The Hermit Formation contains the unstudied trackways, burrows, and resting and feeding traces of invertebrates along with the more common root bioturbation and microbial structures.
[8][9] The Hermit Formation has yielded what is certainly best-preserved and most diverse assemblage of vertebrate trace fossils, including tracks and trackways, known from the Grand Canyon region.