SOUTHERN PACIFIC LINES 139 
far to the south; the Victorio Mountains, to the west; the Good- 
sight Mountains, to the east; and Cooks Ravige with its prominent 
culminating Cooks Peak, to the north. There are also many isolated 
ridges and buttes that rise abruptly from the desert plain. One of 
these, Black Mountain, a prominent isolated mesa 10 miles to the 
northwest, is capped by an eastward-dipping sheet of basalt. Another 
conspicuous feature is Red Mountain, 10 miles southwest of Deming, 
which consists of a large mass of rhyolite: 
The Florida Mountains, southeast of Deming, form the most 
striking feature of the landscape, with exceedingly high rough crags 
all over their higher summits. At one point there is a jagged hole 
through the crest known as Arco del Diablo (bridge of the devil), 
85 feet high by 250 feet long, which is visible from Cambray to Luxor. 
c ¢ cal 
3 mA 3 
5 nas a 
3 Miles 
Jj 
Luna County, a Mex. A, Through 
andstone; e, El Paso 
tones; J, ‘Lobo aitiethies g, Gym limestone; 
k, keratophyre dikes; Agr, granite; ag, ieee agglomerate 
The northern half of the range, like the outlying Little Florida Moun- 
tains, consists of agglomerate and other igneous rocks; the southern 
half is pre-Cambrian granite overlain by sandstones and limestones 
of Cambrian to Permian age. The rocks are tilted and traversed 
by several faults of moderate amount. The principal relations are 
_ Shown in the sections in Figure 30.5 
5In general the range is a tilted 
underlying granite is exposed at the 
block of pre-Cambrian granite capped 
lies under the bolson on th 
side by a fault. At Capitol Dome, at 
the north end of the range, the Paleo- 
zoic rocks and agglomerate deposits all 
dip to the east-northeast, and the 
foot of the western slope. This easter- 
ly dip, with repetition of the limestones 
by faulting, is exhibited again farther 
south in the center of the range, where 
there is a profound fault that trends 
Permian limestone dipping 
east; on the west side of the peak this 
