Laramide Sierra uplift--Evidence for major prerift uplift in central and southern New Mexico
— Steven M. Cather

Eardley (1962) proposed the existence of a Laramide positive area adjacent to the eastern margin of the Colorado Plateau in southern New Mexico and termed it the Sierra uplift. Large portions of this uplift subsided to form basins of the Rio Grande rift during middle and late Tertiary time, thus documentation of a Laramide positive area in this region must depend upon evidence derived from synorogenic sediments, regional stratigraphic relations, and the structural style of remaining, unsubsided portions of the uplift. This paper briefly reviews structural and stratigraphic evidence for the Sierra uplift, and discusses sedimen-tologic data from the Baca Formation (Eocene) which indicate that the uplift extended northward into the Socorro area, approximately 70 km beyond the northern boundary of the uplift as depicted by Eardley (fig. 1).