Page 74 - The Geology and Ore Deposits of Sierra County, New Mexico - Bulletin 10

MINING DISTRICTS 73
supplies. Magdalena, in Socorro County, 90 miles distant, may be reached over fair to good roads during dry weather. The nearest railroad shipping points are Engle, 53 miles from Chlor- ide, and Hatch at a distance of 80 miles. The road to Hatch is much better than the road to Engle, and it probably is preferable when heavy loads of ore are being hauled, in spite of the greater distance.
GEOGRAPHY
The crest of the Black Range, which here is the Continental
Divide, constitutes the west boundary of the district. Altitudes along the crest vary from 7,500 to 8,500 feet. The drainage is all carried eastward by tributaries of Cuchillo Creek, which emp- ties into the Rio Grande just north of the town of Hot Springs.
GEOLOGY
SEDIMENTARY ROCKS
Paleozoic formations outcrop continuously along the eastern slope of the Black Range from the southern extremity of the Apache district to a point about opposite the old town of Robin- son, where, in general conformity with the Black Range dome, they pitch below the average level of the terrane. A second out- crop of limestone, which is north and west of the main exposure and apparently the top of a long faulted block, extends from a point 3 miles south of the county line to a point a mile north of it. This block lies north of Turkey Creek, and within or adjacent to it are the Great Republic, Keystone and Minnehaha mines. One or two smaller patches of these rocks occur in the district at places where uplift of the tilted fault blocks has been pro- nounced.
The oldest sedimentary rocks exposed are of Magdalena (Pennsylvanian) age. These rocks outcrop along the western edge of the zone of sedimentary exposures, along the lower por- tions of some of the fault blocks, and in the isolated areas such as that to the northwest. These beds in general dip to the east, al- though faulting has so oriented some of the blocks that in small areas they are horizontal or have dips in any direction. Overly- ing the Magdalena formation is the Abo (Permian) sandstone, which appears at the surface along the eastern edge of the belt of sediments. These strata dip to the east in general conformity with the dip of the underlying Magdalena beds. One or two thin beds of gray limestone are interstratified with the red sand- stones, and a yellow sandstone member is conspicuous in places and apparently a persistent feature. Some of the beds are shaly, grading into sandy shales and sandstones ; these may contain thin laminae of greenish-gray shale, or they may be spotted with cir- cular blotches of the same color which vary from a fraction of an inch to several inches in diameter. Just north of Chloride red sandstone, in part gypsiferous, appears to overlie the more nor- mal beds of the Abo formation in a small area, and these may be