Low angle, seaward-dipping cross-beds in the upper Tansill Formation. These skeletal
grainstones of probable beach origin overlie subtidal and lower intertidal grainstones
and packstones
(base of photograph) and, in turn, are overlain by pisolitic strata — thus,
they are part of one of the many shallowing-upward sequences in this part of the section,
probably associated with small island barriers in the very near-back-reef zone. These
barriers are thought to have restricted the flow of marine water from the basin onto
the shelf. Outcrop on south side of Dark Canyon, less than 1 km west of the
canyon mouth, Eddy Co., NM.

© Peter A. Scholle, 1999

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