Page 115 - The Geology and Ore Deposits of Sierra County, New Mexico - Bulletin 10

114 GEOLOGY AND ORE DEPOSITS OF SIERRA CO., N. M.
contain a typical Pennsylvanian fauna, which includes species of Productus, Spirifer, Fusulina and corals. Additional limestones occur on the dip-slope side of the ridge, which were not meas- ured, but it was estimated that the Magdalena limestone here is not less than 1,500 feet in thickness. On the eastern slope Abo sandstone of Permian age overlies the Magdalena limestone and forms cuestas near the base of the range. At the foot of the
western escarpment a small down-faulted block has a low outcrop of Abo sandstone projecting through the detrital material of the alluvial apron. Beds of the Chupadera formation, consisting in the lower part of pink and red shales interbedded with gyp- sum (Yeso) and in the upper part of limestone (San Andres), are found overlying the Abo sandstone on the east.
Overlying the Chupadera beds for the most part, but in other places apparently resting directly upon beds of Abo or even of Magdalena age, are extrusives of Tertiary age consisting of the usual sequence, from bottom to top, of flows of andesite, latite and rhyolite and related breccias and tuffs. Dikes of the latite and latite porphyry cut the andesite series, and dikes of