- Inventory Map -
GEOLOGY
The Basin and Range Province, contains the Superstition Mountain Range. This range has a northwest to southeast alignment, with foothills and alluvial valley below, to the southwest. The Study Area is situated along the southern edge of the Superstition Mountains. Geology is dominated by volcanic rocks.
SUPERSTITION CAULDRON
The volcanic stratigraphy of the southern Superstition Mountains changes abruptly from a sequence dominated by lavas in the south, in the foothills, to a sequence dominated by the thick Superstition tuff to the north. The transition corresponds to the southern edge of a large volcanic-tectonic depression referred to as the Superstition Cauldron.
PERALTA-COFFEE FLAT VALLEY
The Superstition Cauldron is bounded on the south by a broad valley, known as Coffee Flat, underlain by Proterozoic basement. This valley is thought to represent the upturned, highly fractured, and therefore recessive, margin of the Cauldron. Drainages flow across, rather than along this valley.
ELEPHANT BUTTE FAULT
The most important structural feature of the Study Area is a major west-side down normal fault that runs along the east edge of the Study Area. The Elephant Butte fault appears to have had a great influence on the Tertiary stratigraphy and volcanic structure of the physiographic region.
THE FOLLOWING GEOLOGIC AREAS ARE FOUND WITHIN THE STUDY AREA:
Surficial Deposits (Q)
(Holocene to Middle Pleistocene)
Older Surficial Deposits (Qo)
(Middle Pleistocene to Latest Pliocene)
Volcanic Rocks (Tv)
(Middle Miocene to Oligocene)
Metamorphic Rocks (Xm)
(Early Proterozoic)
Granitoid Rocks (Yxg)
(Middle or Early Proterozoic)
Granitoid Rocks (Yg)
(Middle Proterozoic)
Sedimentary Rocks (Ys)
(Middle Proterozoic)
| 
