Laminated Castile Formation basinal evaporites. Dark laminae
are calcite plus organic matter; light laminae are gypsum. Laminae
are considered to be varves (annual layers reflecting variations
between summer (evaporitic) and winter (less evaporitic) conditions.
Outcrop along U.S. Highway 62-180 about 1.5 km north of Texas-
New Mexico border, Eddy Co., NM. Coin is 1.9 cm in diameter.
© Peter A. Scholle, 1999