Beaver Creek  
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  Late Paleozoic Sedimentary Rocks:

The late Paleozoic sedimentary rocks comprise two formations from the Pennsylvanian through Permian Periods of the Paleozoic Era .  These Pennsylvanian-Permian formations vary in composition and origin and are part of the regional aquifer. They are, from youngest to oldest:

Permian Coconino Sandstone (~ 265 million years old): The Coconino is a massive, very fine- to fine-grained cross-bedded sandstone unit that is fairly homogeneous in composition.  Unlike the other Paleozoic units in the area, which are mostly interpreted as being of marine origin, the Coconino has been interpreted to be of aeolian origin, representing a time when the sea bordering Permian Western North America was in a regressive phase. Fracturing and jointing are common, as well as parting along bedding planes, facilitating the transmission of water through the unit.  The Coconino Sandstone crops out throughout most of Wet Beaver Creek Canyon and is the source of many springs throughout the watershed.

Crossbeds in Coconino Sandstone, Wet Beaver Creek

Pennsylvanian Naco Formation (~ 300 m.y.): The Naco Formation consists of a limy siltstone, a fine-grained sandstone interbedded with limestone, and a sandy shale and chert breccia layer at the base. Though this formation is not known to crop out in the Beaver Creek Watershed, it is part of the aquifer within the Mogollon Rim area.

Pennsylvanian-Permian Supai Formation (~ 275-320 m.y.): The Supai is divided into several members, ranging in composition from sandstone to siltstone, mudstone, conglomerate, and limestone. The Supai crops out in the southernmost part of the watershed and is part of the regional aquifer.



Owen-Joyce, S.J. and Bell, C.K., 1983 Appraisal of Water Resources in the Upper Verde River Area, Yavapai County, Arizona, Arizona Department of Water Resources Bulletin 2 (Prepared by the U.S. Geological Survey), available online at:


Northern Arizona University         Merriam-Powell Center for Environmental Research         Rocky Mountain Research Station         MAB