Evaporites in the McKnight Formation: Evidence for a Miocene Age to Fresh Water Flushing of the Maverick Basin, Southwest TexasBy Mark E. Thompson and M. Jeff RidingsPetroleum GeologistsSan Antonio, Texas IntroductionThe Maverick Basin is a relatively small depositional basin of Mesozoic age located in extreme southwest Texas (Fig. 1). The basin originated in the Late Triassic to Early Jurassic as a rift basin created during the early formation of the Gulf of Mexico.