Facies Reconnaissance of the Upper Miocene Big Sandy Formation Near Wikieup, Mohave County, Arizona

A brief reconnaissance (5-8 November 2008) of the Big Sandy Formation near Wikieup (on US Highway 93 in Mohave County, Arizona) was undertaken to reconcile a reported dominance of lacustrine beds (Sheppard and Gude, 1972, 1973) with the largely terrestrial mammalian fauna reported from the formation (MacFadden et al., 1979; Lindsay and Mead, 2005). The issue is resolved satisfactorily by appreciation that nearly all fossil localities occur in fluvial beds that intertongue with and grade laterally into the dominant lacustrine strata.