Middle to Late Miocene Paleogeography of Arizona (15-10 Ma).

Hickey Basalts and related volcanics have disrupted Oligocene to Lower Miocene stream systems below the Mogollon Rim. NW-SE trending faults cut the fluvial deposits and some of the basalts. The Verde Fault begins to define Verde Valley. To the south, core complex development and extension are waning and the Colorado River Trough begins to form. To the north, partially dammed strike-valley streams deposit early phases of the Bidahochi Formation.