140 GUIDEBOOK OF THE WESTERN UNITED STATES 
The ridge known as the Little Florida Mountains consists of a thick 
sheet of felsitic or vitreous rhyolite, included in a thick deposit of 
agglomerate apparently somewhat younger than the beds constituting 
the north end of the Florida Mountains. It is possible, however, 
that a fault may pass between the two ranges. The structure is 
shown in Figure 31, in which section A shows the relations that pre- 
vail along the greater part of the ridge and section B shows features 
Scale 
9 1,000 3,000 Feet 
SE carer A . 
SECTION B 
_ 31.—Sections across the Little Florida Mountai , Across center of range; 
miles farther south. ag, Agglomerate; r, felsitic y bahay 8 ae k, keratophyre 
of the faulted portion farther south. Manganese ore is mined in the 
north end of the range. 
The conspicuous ridge a few miles north of Deming is Fluorite 
Ridge, an outlier of the south end of the Cooks Range. It consists 
of a thick central mass of porphyry so intruded as to cause an irregular 
dome-shaped uplift, elongated to the northwest and southeast. The 
strata on the south and east sides of the dome stand nearly vertical, 
but those on the north and west sides have more moderate dips. 
The plane of intrusion is low in the Paleozoic strata at the southeast 
end of the uplift, but it rises rapidly toward the north and west, 
limestone nigel Sct over the 
ane edges of underlying Fussel- 
Silurian), foal (Ordovician), 
(Ordovician) li 
300 feet, consists largely of reddish and 
gray shale and gray to pinkish impure 
limestone, with coarse basal beds. 
Near Capitol Dome, a conspicuous 
peak on the north end of the mountains, 
this formation extends across a fault 
(shown in fig. 30, A) which lifts the 
granite about 1,000 feet to the level 
of the top of the El Paso limestone. 
The uplifted block was eroded to 2 
plain before the deposition of the Lobo 
beds, and therefore their is be- 
lieved to be post-Paleozoic, probably 
Triassic, 
