Trap Spring oil field, located on the west side of Railroad Valley, Nevada, is a combination structural and stratigraphic trap in the Tertiary Pritchard's Station ignimbrite. The reservoir is mainly in fractures caused by

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the cooling of the ignimbrite and local faulting. Structure is related to the valley bounding fault. Numerous unconformities and ignimbrite flows date the structural movement. Exact source of the oil is unknown, however both Tertiary-Cretaceous Sheep Pass Formation and Mississippian Chainman Shale are possible sources.

Oil has been generated in commercial quantities in Nevada. Unconventional traps, reservoirs, and source rocks should be regarded as normal. Exploration for conventional traps and accumulations of hydrocarbons in Nevada may be part of the reason for past failures.

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