A diagenetic cycle exists in the calcium sulfate minerals. Gypsum is deposited by precipitation or by growth of crystals in unconsolidated rocks near the surface. This primary gypsum is replaced, with burial, by anhydrite at a temperature of 42 degrees C and theoretical depth of 2,000 feet. Anhydrite (metagypsum) occurs as beds and pore-fillings. Uplift and removal of overburden cause anhydrite to be replaced by gypsum. Variations in texture distinguish bedded, void-filling, and replacement anhydrite.