Outcrop examination of the basal Phosphoria Formation from several locations along the east flank of the Wind River Mountains and the northern Great Divide Basin, coupled with recent literature studies, results in an interpreted orientation of a lower Permian Shoreline and associated shallow water sediments. This northwest to southeast shoreline divided Wyoming almost in half during Leonardian time. Deposition and later preservation of coquinite sands along part of this boundary is recognized and the potential of this trend to hydrocarbon accumulation is discussed.