Abstract Reef complexes of Mississippian, Pennsylvanian, and Early Permian age are conspicuous in the western escarpment of the Sacramento Mountains of southeastern New Mexico (Fig. 1). The coincidence of reef trends and the fault zone at the western front of the Sacramento Mountains appears to be significant. The basement fault zone on the western edge of the Sacramento block created platform margins along which Paleozoic shelf-edge reefs accumulated. Facies in Late Paleozoic formations were strongly controlled by structural trends in the Precambrian basement rocks. The Sacramento escarpment lies parallel to and adjacent to the western margin of the "Pedernal Landmass” (Pray, 1961) that trends northerly, as do the Sacramento Mountains. The La Luz Anticline (Pray, 1961) in the northern part of the Sacramento Mountains plunges to the north(Fig. 1). Beds on the west limb dip 8 to 12 degrees. Numerous deep canyons off this west flank expose thick sequences including nearly all the Paleozoic formations. Exposures perpendicular to the reef-trends thatare available in these canyons (Fig. 2) are unique. Facies Figure changes in the reef complexes are readily available to the field geologist. This area of the Sacramento Mountains is of extreme importance to students of carbonate rocks because of the excellent, numerous, and distinct exposures of the reef complexes.