Five major areas are discussed separately, for the most part, except in those cases where features in one map area may bear upon features in another map area. All areas were surveyed on foot to obtain the best accuracy. In a few cases, the position of certain features or the identification of formations was obscure;
in those cases I used my best judgment. To facilitate accuracy, multiple station lines and triangulation was used in many areas. In many areas, geographic and man-made features are included to permit geologic features to be found, if required.

Our interdisciplinary team of a geologist and volunteers, working with the City of Scottsdale and the McDowell Sonoran Conservancy (MSC), has confirmed that an unusual rock outcropping in the McDowell Mountains within the McDowell Sonoran Preserve in Scottsdale is travertine, a form of limestone. Limestone has not been identified previously in the McDowell Mountains or in the metro Phoenix area. This research is part of a coordinated effort on the part of MSC and the City of Scottsdale’s Preservation Division to use the talents and energy of MSC volunteers to better understand the geologic setting of the McDowell Sonoran Preserve. Travertine is a whitish sedimentary rock consisting of calcium carbonate. Travertine forms when calcium carbonate is deposited by mineral springs. There also is evidence of possible plant fossils and algal residue associated with the travertine. Our preliminary analysis indicates that the travertine was deposited 2 to 20 million years ago, during the formation of the McDowell Mountains.

A brief reconnaissance (5-8 November 2008) of the Big Sandy Formation near Wikieup (on US Highway 93 in Mohave County, Arizona) was undertaken to reconcile a reported dominance of lacustrine beds (Sheppard and Gude, 1972, 1973) with the largely terrestrial mammalian fauna reported from the formation (MacFadden et al., 1979; Lindsay and Mead, 2005). The issue is resolved satisfactorily by appreciation that nearly all fossil localities occur in fluvial beds that intertongue with and grade laterally into the dominant lacustrine strata.

To provide insight into provenance relations for multiple mid-Oligocene to mid-Miocene subbasins
(typically half-grabens) dissected by erosion in uplands lying north of the Catalina core complex and west of the San Pedro trough, 136 outcrop counts were made of clast types in tilted conglomerates of the Cloudburst and San Manuel Formations and their lateral equivalents in exposures as far north as the Gila River near Kearny. Clast counts were not made for younger conglomerates of the post-mid-Miocene Quiburis Formation, which fills the San Pedro trough and onlaps flanking uplands (Dickinson, 1998), because Quiburis clast assemblages in all cases match bedrock sources exposed uphill on the modern landscape. By contrast, paleotopography during Cloudburst and San Manuel deposition can only be inferred from local paleocurrent indicators (clast imbrications; figure 39 of Dickinson, 1991, p. 70-71) and clast assemblages in tilted strata. Areas included in this study were the Guild Wash allochthon between the Tortolita and Suizo Mountains, the Star Flat allochthon on the east flank of the Black Mountains, the
Black Hills (west of Mammoth), Camp Grant Wash (and Putnam Wash) between the Black Mountains and the Black Hills, multiple drainages of the Tortilla Mountains (Eagle Wash, Jim Thomas Wash, Hackberry Wash, Indian Camp Wash), and Ripsey Wash on the west flank of the Tortilla Mountains (Figs. 1-4).

This report details geothermal resource exploration done for Arizona Public Service and the U.S. Department of Energy in 2005 to evaluate the geothermal resources of the Clifton Hot Springs area in Greenlee County, eastern Arizona for electric power production. The intent of the evaluation was to determine the local geologic controls of the geothermal system and, using publicly available data and original mapping performed for this project, to recommend locations for Controlled Source Audiomagnetotelluric (CSAMT) cross sections. The results of the geophysics were then combined with the geologic mapping to site three gradient holes, two of which were drilled to depths of 635 feet and 1,000 feet, respectively.

Some of the richest helium-bearing gas in the world was produced in Arizona. Helium concentrations range from trace amounts up to ten percent in the Holbrook Basin and Four Corners. Both areas have good potential for additional discovery and production of helium. Includes metadata for the monthly, annual, and cumulative summary reports of oil, gas and helium production by Arizona drilling fields.

From May 2005 to June 2005, the Arizona Department of Environmental Quality conducted a study, Potable Well Sampling Task 4.0, to determine if the chromium and chromium VI plume due to the discharge of the Pacific Gas and Electronic Topock Compressor Station has migrated under the Colorado River and impacted water supplies in Arizona. The ADEQ investigated the total chromium and hexavalent chromium (chromium VI) concentrations in (1) public water supply wells, (2) combined industrial and domestic water supply wells, and (3) private domestic water supply wells at Topock and Golden Shores, Arizona. The communities of Topock and Golden Shores have expressed their concerns regarding the findings. Thus, the ADEQ requested the Arizona Department of Health Services to evaluate the potential health effects of exposure to well water contaminated with chromium.

The Arizona Department of Health Services completed this health consultation at the request of the Arizona Department of Environmental Quality. This consult evaluates whether soil vapors from volatile organic compounds in the subsurface near the Silver Creek Subdivision in Tucson, Arizona are present at levels that may cause adverse health effects.

The Stoneridge subdivision is a growing rural community with approximately 5,000 residents. The Prescott Valley Water Company (Prescott Valley, AZ) provides drinking water for residents in this area. A resident in the community indicated that there is a “paint thinner” type odor coming from the tap water. The Prescott Valley Water Company sampled the water due to request of the resident. On July 27, 2004, the resident called the Arizona Department of Health Services to express his/her concern regarding the analytical results of benzene in tap water samples collected from faucets inside the house. As a result, the Arizona Department of Health Services completed a health consultation to evaluate if benzene and other volatile organic compounds in the water supplied by the Prescott Valley Water Company pose any adverse health effects.

The Arizona Department of Environmental Quality and the California Department of Toxic Substance Control worked together to assess background levels of naturally occurring metals in groundwater wells at Topock and Golden Shores, Arizona. The communities expressed concerns regarding the findings, thus the ADEQ requested the Arizona Department of Health Services to evaluate whether these naturally occurring metals in groundwater wells are present at levels that may cause adverse health effects.