The Lyndon Limestone was named by Westgate and Knopf (1927) for exposures along Lyndon Gulch on the western flank of the Highland Range, in T. 1 S., R. 66 E.

The Lyndon Limestone is lower Middle Cambrian in age. It conformably overlies the Pioche Shale in the southern portion of Lincoln County and is equivalent to the lower portion of the Pole Canyon Limestone in northern sections (Tschanz and Pampeyan, 1970).

The Lyndon Limestone is a massive, cliff-forming limestone which in the Pioche area is dark gray in the upper and lower portion, and nearly white in the middle of the formation (Tschanz and Pampeyan, 1970). The lower portion of the Lyndon is fine-grained and dark, while the upper limestone is coarsely crystalline, thick-bedded and commonly a light gray color (Westgate and Knopf, 1932).

The Lyndon Limestone is 345 to 400 feet thick in the Highland Range and Pioche Hills area (Westgate and Knopf, 1932).

The Lyndon Limestone is present to the south of the evaluation area in the Groom and Desert Ranges and Mormon Mountains, as well as in adjacent portions of Arizona and Utah. It is only present in the Highland Range in the evaluation area, and just to the south of the area in the Pioche Hills.

The details of depositional setting for the Lyndon Limestone are poorly understood. In general the Lyndon appears to represent shallow marine shelf deposition.