Geology of Ft. Apache Region, Ariz. — Reagan. 297 
Dikes and Veins in the vicinity of Globe. — Around Globe 
a great many dikes and veins penetrate the country rock, at 
some points presenting a mesh-like arrangement, while in oth- 
ers they show a radiating position. 
The veins are usually mineral bearing. On these are locat- 
ed the Old Dominion, the McMillen, and the other mines of 
the region. 
The Ellison Dike. — Just east of Ellison and west of the 
west line of the White mountain Apache Indian reservation is 
a north and south porphyritic dike averaging one-fourth of a 
mile in width where it emerges from beneath the Tonto near 
Juniper butte. The porphyry is copper stained throughout and 
on it are located the Ellison copper prospects. Its extent is not 
known to the writer farther than that it extends several miles 
south of the Government trail. It seems to be an uncovered 
dike of Algonkiau age. 
The Kelley dike. — The Salt river dike is continued in the 
vicinity of Fort Apache in the Kelley dike. This division, 
which is only occasionally exposed, is composed of basalt. On 
it are situated a line of a dozen or more craters and volcanic 
necks. From this dike a branch is given off which extends in 
a northeast direction through the Sugar Loaf and Sanchez 
butte, and Green Point regions to the east, Mogollon range and 
the White mountains. On this dike and its northeast branch 
were situated some of the most active volcanoes 01 the Quater- 
nary Period. 
The White Mountain dikes. — Only a reconnoissance was 
made of the White mountains, but enough evidence was ob- 
tained to demonstrate that a volcanic dike (or dikes) extends 
in a north and south direction through the entire mountain 
district and on north and northwest toward the San Francisco 
mountains. At one time this dike was the vent of a trachyte 
(rhyolyte) fissure eruption and on it at a later time were lo- 
cated the north and south line of the basaltic craters which 
now dot the region. This dike seems to be the vent from 
which the greater , part of the lavas now covering the region, 
and described in this paper, were ejected. 
Other Dikes. — There are many other dikes and veins in 
the region, among which are the Gneissic dikes in the Archaean 
granite near the confluence of Canyon creek and Salt river 
and the dikes in the Cherrv creek and East Tonto basin. 
