Stratigraphic and facies analyses of the Toroweap Formation have yielded reliable indicators of the paleogeographic conditions that existed in northern Arizona during the Permian. Four depositional environments have been recognized that are based on definitive facies. The four environments and their respective facies laterally from west to east are: (I) open marine; skeletal packstone and wackestone, pelletal wackestone; (II) restricted marine; aphanitic lime mudstone, dolomite mudstone, sandy dolomite; (III) sabkha; gypsum, horizontal and gnarly bedded sandstone; and (IV) eolian dune; cross-bedded sandstone.

A marine transgression encroached upon coastal and continental sabkhas eventually drowning a large eolian dune field in its eastward advance across northern Arizona depositing the Toroweap Formation. Eventually the sea slowly withdrew westward and thick prograding

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sabkha and dune facies were deposited over marine carbonate rocks. Desert conditions prevailed at the eastern edge of the sea as it transgressed eastward and regressed westward across northern Arizona. Eolian dunes with south-dipping cross-beds were formed by trade winds blowing southward toward the paleoequator south of Arizona during the Permian. Extensive coastal and continental sabkhas formed between the restricted mud flats and the dune fields. Westward, the restricted marine deposits of dolomite characterized by bivalves and gastropods gave way to shallow open-marine deposits of brachiopods, byrozoans, corals, and crinoids. The westward regression ended with a rapid transgression that deposited the Kaibab Limestone across the sabkhas and dune fields of the Toroweap and Coconino ormations.

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