Geologic map and geologic hazards of the Three Points Quadrangle, Pima County, Arizona

Pearthree, P.A.; Ferguson, C.A.; Gilbert, W.G.; Skotnicki, S.J.

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OFR00-12report-ThreePoints.pdf

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Citation

Pearthree, P.A., Ferguson, C.A., Gilbert, W.G., and Skotnicki, S.J., 2000, Geologic map and geologic hazards of the Three Points Quadrangle, Pima County, Arizona. Arizona Geological Survey Open File Report, OFR-00-12, 1 map sheet, map scale 1:24,000, 19 p.

Description

This report and maps describe the geology, geomorphology, and geologic hazards in the Three Points quadrangle, on the southwestern fringe of the Tucson metropolitan area in unincorporated Pima County (Figure 1). The map area is located in the transition between the upland, moderately dissected Altar Valley to the south and the broad, undissected basin called Avra Valley to the north. The community of Three Points (also called Robles Junction) lies on the approximate boundary between these two geographic areas. The map includes a nine-mile-long reach of Brawley Wash, which cuts through the map area from southwest to northeast. Brawley Wash heads just south of the U.S. – Mexico border and drains all of Altar and Avra valleys before joining the Santa Cruz River northwest of Tucson. About 60 percent of the Three Points quadrangle consists of the northwestern piedmont of the Sierrita Mountains. The quadrangle also includes a small part of the northwestern piedmont of the Coyote Mountains and the southern fringe of the Roskruge Mountains. The quadrangle is generally undeveloped, and is currently used primarily for grazing. Some low-density suburban development has occurred around the community of Three Points and on the Sierrita and piedmont to the south. Much of the floodplain and terraces of Brawley Wash has been developed for agriculture. The Three Points quadrangle will likely experience much more urban/suburban development in the next few decades. This map and report may be of use in avoiding or mitigating geologic hazards in this area. (21 pages)

URI

http://hdl.handle.net/10150/629753

Additional Links

https://library.azgs.arizona.edu/item/AOFR-1552429222851-744

Language

Series/Report no.

OFR-00-12

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Collection Information

Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact azgs-info@email.arizona.edu.

North Bounding Coordinate

32.1198

South Bounding Coordinate

31.9149

West Bounding Coordinate

-111.5

East Bounding Coordinate

-111.204

Collections

AZGS Document Repository