MOH and I spotted this rock formation in dark-colored volcanic rocks west of the town of Midas, NV, and called it Nodding Rock. The rock formation is part of a widespread group of rhyolite to rhyodacite flows, domes, and densely welded ash-flow tuffs (and rheomorphic tuffs?) that cap the Owyhee Bluffs and other nearby hills and plateaus of the Snowstorm Mountains near Midas: the volcanic rocks of Jake Creek Mountains, middle or upper middle Miocene in age.
General location (MSRMaps): the ridgeline about 1 mile west of Midas, south of hill 7230 and just north of the change in map coverage.
A Few References:
Wallace, A.R., 1990, Geologic map of the Jake Creek Mountain quadrangle, Elko County, Nevada: U.S. Geological Survey, Geologic Quadrangle Map GQ-1672, scale 1:24000.
Wallace, A.R., 1993, Geologic map of the Snowstorm Mountains and vicinity, Elko and Humboldt Counties, Nevada: U.S. Geological Survey, Miscellaneous Investigations Series Map I-2394, scale 1:50000.