“…The tuff units are widespread southwest of the Marysvale field in southwestem Utah and southeastern Nevada (Mackin, 1960;Anderson and Rowley, 1975;Siders and Shubat, 1986;Best, Christiansen, and others, 1989;Best and others, 1993;Rowley, Nealey, and others, in press;Scott and others, in press). Many are intertongued with Marysvale rocks only in the southwestern part of the Marysvale field (in the southern Black Mountains and Markagunt Plateau); an exception is the Wah Wah Springs Formation, which is distributed over most of the Marysvale field (Row ley, Anderson, and others, 1978;Best, Christiansen, and Blank, 1989).…”