SOUTHERN PACIFIC LINES 137 
The southern part of New Mexico is underlain by an extensive 
series of formations representing various parts of geologic time from 
pre-Cambrian to Recent. Most of them are also present in western 
Texas, as described in preceding pages. Those that are exposed near 
Deming and westward near the Southern Pacific Railroad are listed 
in the following table: 
Geologic formations of southwestern New Mexico 
Age Group and formation Character and general relations By ised 
Recent. Alluvium. Sand, gravel, and silt of river bottom, 0-1, 000 
desert floors, and fans 
‘Unconformity- 
Pleistocene and Yaienic = and asso- | Lavas, ash, tuff, a a conglomer- 700-1, 400 
Tertiary. its. ate, and sandston ? 
Upper Cretaceous. Colorado she cate Dark shale. (?) 
Sarten sai Gray sandstone. 
Lower Cretaceous 450 
(Comanche). Limestone of Comanche | Limestone. 
Tseoatomniicy 
Triassic? Lobo formation. yer conglomerate, and sandstone, partly 0-350 
Unconformity- 
Permian, Gym limestone Limestone, massive and slabby. 30-1, 000 
Pieters dg | 
Pennsylvanian, Mag ion. Limestone, with some shale. 0-40 
. ; Unconformity=— 
Mississippian. tone. Limestone. 0-700 
Devonian. Percha shale. Black shale. 0-175 
Silurian. Fusselman limestone. Limestone, massive. 100-300 
Serer Limesto: ith chert ber abo 
Montoya limestone. nwo 0-300 
Ordovician. Vadertcrmitty: sandy below. 
E] Paso limestone. Limestone, slabby; weathers light gray. 500-800 
Cambrian. papa aa ie Sandstone, massive to slabby, glauconitic. 30-200 
Pre-Cambrian. oe Granite and schist. 
Deming is a long-established ee center, railroad junction, 
irrigation interests. Here the 
and headquarters for minin 
Atchison, Eopeltae & Santa Fe Railway from Albu- 
nua not, duerque passes on the way to Silver City, and there 
Population 3,377, 1S @ branch railroad connecting with the south line 
New Orleans 1,276 of the Southern Pacific at Hermanas. There is now 
; but little mining in the immediate vicinity, but ores 
of various kinds have been produced in the adjoining mountains, 
note " fuotite (calcium fluoride) from mines 10 miles northeast, an 
manganese ore from a mine in the north end of the Little Florida 
There are extensive mines at Silver 
Mountains, 12 miles southeast. 
City and near Santa Rita, about 50 miles northwest of Deming. 
However, the undergro 
und water in the sand and gravel about 
Deming and southward is the most important economic resource 
in the region, and it is utilized extensively in irrigation. 3 It lies 
3 Described by N. H. Darton in U.S. Geol. Survey Bull. 618 and Water-Supply 
Paper 345-C. 
152109°—33——10 
