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Figure 1.  Simplified geologic time scale for Quaternary river (r) and piedmont deposits along the San Pedro River. Figure 2.  Generalized cross section of geomorphic relationships between Tertiary basin fill (Tsy), Pleistocene piedmont and river (Qin and Qinr units) deposits, and Holocene piedmont and river (Qyn and Qynr units) deposits.

The Arizona Geological Survey is releasing six, new geologic map sheets showing the extent and age relationships of Quaternary alluvium along more than 175 miles of the San Pedro River and its major tributaries, Aravaipa Creek and Babocomari River.  A 76-page report accompanies the maps. 

The Arizona Department of Water Resources (ADWR) used the geologic maps, in conjunction with other data, to delineate subflow zones in the watershed. ADWR serves as a technical advisor to an adjudication court which requested that subflow zones be mapped as part of its larger effort to adjudicate water rights of the Gila River and its tributaries. (See azwater.gov for details.)

AZGS geologists mapped geologic units along the river on the basis of age and origin – i.e., river alluvium, tributary alluvium, basin deposits, bedrock.  See the graphics on the right for formal subdivisions of Quaternary deposits – Holocene and Pleistocene – and an idealized cross-section of geomorphic relationships of Quaternary units and Tertiary basin fill.

The geologic maps, which encompass a two-mile wide swath centered on the river, provide foundational geologic data, i.e., context, for deciphering the past 10,000-year history of the San Pedro river system. Stakeholders – water managers, civil authorities, ranchers, wildlife biologists, archeologists, environmentalists, and the Arizona public – should find these maps indispensible in considering the physical and biological character of the San Pedro riparian corridor.

The report and six geologic map sheets, all at 1:24,000 map scale, are available free as PDF downloads from the AZGS Online Publication Outlet and below on this page.

For GIS users, the geodatabase, shapefiles and metadata are available along with the report and browse graphics on CD-ROM from the AZGS Bookstore for $25.00 (call 520.770.3500). Hard copies of the report and maps are also available.

Essential features

• Geology displayed on six map sheets at 1:24,000 map scale.
• 76-page report includes detailed description of Quaternary deposits.
• Geologic mapping is confined to a 2-mile corridor centered on the watercourse.
• Focus is on Quaternary age alluvium with especial emphasis on Holocene deposits.
• Final map product encompasses parts of 35 USGS 7.5’ topographic maps.
  

Map Areas

• San Pedro River map -- 125 miles from US-Mexico border to confluence with Gila River.
• Aravaipa Creek map -- from headwaters to confluence with San Pedro River.
• Babocomari River map -- from headwaters to confluence with San Pedro River.

NOTE: Holocene mapping along the San Pedro River ties in with earlier, and some ongoing, 7.5’ geologic quadrangle mapping by AZGS -- from south to north:  Stark, Hereford, Lewis Springs, Tombstone SE, Huachuca City, Land, Saint David, Benson, Galleta Flat E., Wildhorse Mountain, Soza Canyon, Redington, Peppersauce Wash, Mammoth, Clark Ranch, and Lookout Mountain. 

Full Publication Citation: Cook, J.P., A. Youberg, P.A. Pearthree, J.A. Onken, B.J. Macfarlane, D.E. Haddad, E.R. Bigio and A.L. Kowler, 2009, Mapping of Holocene River Alluvium along the San Pedro River, Aravaipa Creek, and Babocomari River, Southeastern Arizona, 76 p., 6 map sheets, DM-RM-1.

Download Maps and Report:

(right click, save-link-as...)

DM-RM-1.1 Report : Mapping of Holocene River Alluvium Along the San Pedro River, Aravaipa Creek, and Babocomari River, Southeastern Arizona, J.P. Cook, A. Youberg, P.A. Pearthree, J.A. Onken, B.J. MacFarlane, D.E. Haddad, E.R. Bigio and A.L. Kowler. (4.6MB)

Geologic Maps of the San Pedro River, Babocomari River and Aravaipa Creek Corridors, Southeastern Arizona, J.P. Cook, D.E. haddad and P.A. Pearthree, 2009.

DM-RM-1.1A: (18MB) Preview as JPG(4.82MB) GISDATA

DM-RM-1.1B: (28.3MB) Preview as JPG(5.13MB) GISDATA

DM-RM-1.1C: (34MB) Preview as JPG(7.75MB) GISDATA

DM-RM-1.1D: (38MB) Preview as JPG(8.08MB) GISDATA

DM-RM-1.1E: (31.7MB) Preview as JPG(8.51MB) GISDATA

DM-RM-1.1F: (50.7MB) Preview as JPG(10.6MB) GISDATA

NOTE: We are releasing revised versions of the DM-RM 1 report and maps (version 1.1) that clarify geologic mapping sources and original sources of map unit descriptions in the report. The geologic mapping depicted in the map sheets is unchanged. (10.09.09)

For Printed copies, more info, or to purchase GIS Data on CD-ROM:
Contact Michael Conway at the AZGS Map and Bookstore. 416 W. Congress, Ste 100 Tucson, AZ 85701. Call 520.770.3500 or Email storeazgs.az.gov

Related Downloads:

San Pedro River Geologic Poster . Free 11"x17", 2.7MB, .jpg, ready-to-print, continuous geologic strip map from the US-Mexico frontier to the confluence with the Gila River. Wall-sized versions (74"x31") will be made available through the AZGS Map and Bookstore in mid-August.