Massive nodular gypsum in the Seven Rivers Formation. Although nodular
usually are interpreted as indicative of formation in coastal sabkha settings, such
nodular structures can also be produced diagenetically in evaporites of other origins.
These evaporites probably have been converted from anhydrite to gypsum during
Tertiary/Quaternary uplift. Outcrop in borrow pit along Dark Canyon road near
intersection with New Mexico Highway 137, Eddy Co, NM.
© Peter A. Scholle, 1999