Basalt – Approximately 130 feet thick. As described by Wilburn, there are 1 meter beds +/- of welded tuff in the middle of the basalt, the Saddle Rock Tuff.
The lower portion of the basalt is named the Weekes Wash basalt(Fodor, S.K. Vetter) and is higher in silica than the upper basalt, and some trends to andesite.
Whitetail Assemblage – Wilburn describes the Whitetail as lying unconformably on the granite up to a thickness of 500 feet. The upper Whitetail is approximately 250 feet thick, and contains more conglomerate than the lower Whitetail, varying from thin conglomerate beds in the sandstone to dense cobbles at the top. A large percentage of the cobbles are limestone and marble.
The lower portion of the Whitetail (approximately 250 feet thick) is nearly conglomerate-free. Snotnicki & Ferguson (Geologic Map of the Goldfield Quadrangle) label the lower portion of the Whitetail as Tertiary Sandstone(Ts). This arkosic sandstone is composed of fragments of eroded granite.
Pre – Cambrian Granite – This is the basement rock and varies in texture from a medium equi-granular granite to that of pegmatite granite with large phenocrysts of Orthoclase approximately 2 inches in width.
The arkose breccias on the west side of the Molly Marie Caldera cut the granite, Whitetail assemblage, and basalt.