The Galiuro Mountains
Remote... primeval... rarely visited. These terms describe the nearly 120 square
miles of the Galiuro Wilderness, an area of rugged beauty and isolation 50 miles
northeast of Tucson, Arizona. The wilderness comprises much of the Galiuro Mountains,
a "desert island" range bounded on the west by San Pedro River Valley, on the east
by Sulphur Springs Valley, and on the northeast by Aravaipa Valley. Travelers on
State Highway 77 can see the western scarp of the mountains at a distance, but the
only access to them is by foot or horseback on forest trails. The Galiuros have
borne this name since about 1870; earlier references called them the San Catistro
or San Calisto mountains, and the Sierra del Aravaipa.
The Galiuro Mountains and Vicinity. (click on image for a PDF version)
The most prominent peaks in the Galiuros reach elevations above 7,000 feet. Canyons
and north slopes at higher elevations support ponderosa, Chihuahua and Mexican white
pines, Douglas-fir, Arizona cypress, and Mexican piñon trees. Elsewhere the
mountains exhibit moderate to dense growth of alligator and Utah juniper, piñon,
and several kinds of oak. In the foothills and on the lower slopes one finds heavy
stands of manzanita, mountain mahogany, mesquite, acacia, scrub oak, cacti, and
other brush. Much of the range is rough and brush-covered. Along the watercourses,
riparian growth includes Arizona sycamore, alder, ash, bigtooth maple, walnut and
Apache plume. Although there are no permanent streams or lakes, surface water may
be found at springs, many of which have been improved for livestock use. None of
this country has been commercially logged.
Powers Garden along Rattlesnake Creek.
This is a relatively young mountain range, formed in mid-Tertiary times by block-faulting
and uptilting of the earth's crust. The upper part of the geologic sequence is made
up of thick deposits of relatively young volcanic rocks known as the Galiuro Volcanics.
These rocks, mainly ash fall deposits and lava flows, overlie older granites, quartzites
and other formations. Structurally the Galiuros consist of two high, parallel ridges
separated by two valleys, one sloping north and the other to the south. These deeply
incised valleys, Rattlesnake and Redfleld, run parallel to the lengths of the ridges.
High-angle drainages dissect the mountain slopes fronting on the San Pedro and Aravaipa