Geologic map of the Poachie Range, Yavapai and Mohave counties, Arizona

QfAlluvial and debris fans (Holocene) Bouldery gravel, sand and silt mantling surfaces where major drainage systems change gradient.Examples are along the sides of the Big Sandy River valley.One to several meters thick Qal Alluvium (Holocene) Gravel, sand, and silt in washes and on modern floodplains.Generally 1 to 3 m thick Qpg Pediment gravel (Holocene) Coarse grained gravel, sand, and silt mantling gently sloping surfaces.Generally 1 to 3 m thick Ql Landslide deposit (Holocene and Pleistocene) Boulders and blocks of basalt or granite in a matrix of sand and silt.Irregular hummocky surface.A meter to several meters thick Qtc Talus and colluvium (Holocene and Pleistocene) Angular fragments of rock in matrix containing various proportions of sand and silt.A meter to a few meters thick Qof Older alluvial and debris fans (Pleistocene) Coarse gravel, sand, and silt mantling dissected surfaces where drainage systems change gradient.Examples are along the sides of the Big Sandy River valley.One to several meters thick Qoa Older alluvium (Pleistocene) Gravel, sand, and silt capping terraces along major drainages.Contains stream rounded pebbles, cobbles, and locally, boulders.Best developed along the Big Sandy River valley where it is as much as 6 m thick Qop Older pediment gravel (Pleistocene) Coarse gravel, sand and silt mantling gently sloping, dissected surfaces.Generally 1 to 3 m thick Tgy Younger gravel (Pliocene or Miocene) Coarse gravel, sand, and silt deposits related to present drainage pattern but deeply dissected.As much as 10 m thick Tbi Basalt plugs (Miocene) Olivine and pyroxene basalt in plugs that probably served as feeders for some basalt flows Tg Gravel (Miocene) Gravel, sand, and silt.Locally contains boulders a meter or two in diameter.Interfingers with basalt flows and contains rare beds of tuff and tuffaceous sand and gravel in western part of map area.In northeastern part of area interfingers with and overlies Miocene rhyodacitic volcaniclastics ( Tvc) and is overlain by basalt (Tby) and has some lahars in its lower part.Deposit north of wash northeast of U.S. Highway 93 may be younger.Maximum thickness about 120 m Tby Younger basalt (Miocene) Olivine and pyroxene basalt flows.One to five flows form mesa cap 5 to 45 m thick Ta Andesite (Miocene?)Olivine clinopyroxene andesite forming small plug at south margin of map area in sec.17, T. 12 N., R. 11 W. Tbl Lower basalt (Miocene) Olivine and pyroxene basalt and andesite flows on south flank of Poachie Range, where flows and interbeds of gravel are locally about 150 m thick, and in tilted fault blocks in Big Sandy River valley.Unconformably overlain by Tby in Government Wash area