The drainage is situated across the Mogollon Rim, which separates the Colorado Plateau and the Verde Valley. The sedimentary rocks below the volcanic cover are porous and permeable because of their origin and the abundant fracture systems developed in them. Of the rock types exposed on Beaver Creek, the basaltic and andesitic lavas are the least porous and permeable. When unfractured, they are essentially impervious to water. The cinder deposits are highly porous even when cemented.
Water falling on the cinder cones percolates downward and produces very little surface stormflow.
However, because the cones are built upon a lava base, the permeability of this base determines whether the water continues downward to the regional water table or seeps out along the base of the pyroclastic materials. The slope-controlled distribution of streams has produced a subparallel drainage system of numerous, closely spaced streams. The relationship of cinders to runoff in the Beaver Creek watersheds. Final Report Prepared by Northern Arizona University, Flagstaff, Arizona, Submitted to the Rocky Mountain Forest and Range Experiment Station, Flagstaff, Arizona. Beus, S.S. 1968.