Bulletin 58—Geology of Dog Springs Quadrangle, New Mexico

By D. B. Givens, 1957, 40 pp, 1 plate, 1 index.

Dog Springs quadrangle lies within the Gallinas Mountains of west-central NM, approximately 30 mi northwest of the town of Magdalena.

The oldest rocks that crop out in the quadrangle are Triassic continental Chinle shales. Above the Chinle are the following sedimentary formations: Dakota, nonmarine Upper Cretaceous sandstone; Mancos, marine Upper Cretaceous shale; Mesaverde, nonmarine and marine Upper Cretaceous sandstone; and the Baca, Eocene continental arkose. Overlying the Baca Formation are the quartz latite tuffs of the Spears Ranch member and the rhyolite tuffs of the Hells Mesa Member of the Datil Formation. Resting on the Datil Formation are the Santa Fe gravels and basalts; these in turn, are overlain by recent gravels. Intruded into the section are basalt plugs and dikes of Pleistocene age.

Structurally the area is characterized by broad-scale northwest trending, southeast plunging folds of Eocene age, and broad-scale, northeast trending folds of Pleistocene age. Several north-trending normal faults of considerable displacement cut the sedimentary and volcanic rocks of the area.

Physiographic evidence suggest that the San Augustine Plains were once a topographic high and the source of the Santa Fe gravels.

Note: A place-name in the PDF files has been updated to reflect the current name.