Thin-section photomicrograph (cross-polarized light with gypsum plate) of a near-back-reef
grainstone in the Tansill Formation. The predominant grains are gastropods and bivalves that
were encrusted penecontemporaneously with inorganic marine cement (cloudy, fibrous to bladed
crusts). The sample subsequently was subjected to leaching of the originally aragonitic molluscan
grains, presumably as a result of local meteoric exposure. Sample from Walnut Canyon (New
Mexico Highway 7), less than 1 km west of the canyon mouth, Carlsbad Caverns National Park,
Eddy Co., NM. Long axis of photo = 6 mm.

© Peter A. Scholle, 1999

Guadalupe Mtns. geology —— Scholle home page —— NM Bureau staff page —— NM Bureau main page