The map encompasses a drainage divide that separates the Colorado River catchment from the Red Lake Playa catchment. Valleys consist of gently sloping piedmonts covered by alluvial fan and terrace deposits, and nearly flat valley floors occupied by ephemeral washes, floodplains and low terraces.

The northern Plomosa Mountains are a small metamorphic core complex in La Paz County, western Arizona. The dominant structure of the range is the Plomosa detachment fault, a low-angle normal fault that separates a single tilted footwall block from a highly extended hanging wall with diverse stratigraphy and complex structure. The northern Plomosa Mountains were first mapped by Scarborough and Meader (1983), with later detailed mapping of smaller areas by Stoneman (1985) and Steinke (1997). The Arizona Geological Survey (AZGS) mapped the northern Plomosa Mountains at 1:24,000 scale (Spencer et al., 2014) with funding from the STATEMAP program, a component of the National Geologic Mapping Act of 1992. This field trip is largely a showcase for geology mapped during the AZGS mapping project. On Day 2 we will be visiting several outcrops of the controversial Bouse Formation in the southern part of the Blythe basin. Bouse deposits were first systematically investigated and formally defined as a geologic formation as part of USGS geohydrology investigations along the lower Colorado River (Metzger, 1968; Metzger et al., 1973; Metzger and Loeltz, 1973). These investigations described the basic characteristics of the Bouse Formation, including: (1) basal carbonate deposits including limestone, tufa (travertine) and marl; and (2) much thicker fine-grained siliciclastic deposits consisting of interbedded clay, silt, and quartz-rich sand that are always stratigraphically above the basal carbonate. Based primarily on interpretations that some of the microfauna found in southern Bouse deposits were marine organisms (Smith, 1970), and to a lesser degree on interpretations of sedimentary environments (e.g., Buising, 1990), the Bouse Formation was interpreted to be entirely marine/estuarine.

This bibliography provides references for each known metallic mineral district in La Paz, Mohave, and Yuma Counties in Arizona. In a mineral district classification, known metallic mineral occurrences are grouped according to geologic and metallogenic criteria rather than the geographic associations used in the traditional mining-district approach (Keith and others, 1983a,b). Ideally, a mineral district should consist of mineral occurrences that have a common genesis. A mineral-district classification is especially useful for understanding the geologic setting of mineralization and the distribution of known mineral occurrences with similar geology. A mineral district map, however, is by no means a statement of mineral potential because future mineral discoveries within and outside established districts will affect district boundaries. Although understanding the distribution of known mineral deposits is essential in evaluating mineral potential, many other geologic and technologic factors must also be considered (Fellows, 1984).

The Gene Wash 7.5' Quadrangle is located south of Lake Havasu City and includes part of Mohave and La Paz Counties of western Arizona and San Bernardino County, California. Only the Arizona part of the quadrangle was mapped for this study.

Recent statutory and regulatory changes that affect Federal mining claims have made portions of Special Report 12, Laws and Regulations Governing Mineral Rights in Arizona, 9th Edition inaccurate. Pending the completion of the rewriting of Special Report 12 this circular attempts to briefly describe statutory and agency policy changes in mining claim procedures. These changes are especially pertinent for the information on Federal filing requirements, maintenance of title, surface management regulations, and patenting of claims on pages 28 to 45. Department circulars that describe previous changes are: Arizona Mining Law Change – 1989 (Circular 30) Arizona Recordation Law Change, 1991 (Circular 36) Annual Assessment Work Requirements Under Arizona Statue, 1994 (Circular 56) These circulars, included in Special Report 11, should also be reviewed. It is important for claimants to keep informed as Congress or managing agencies make additional changes to mining law or regulatory procedures.

The public land laws of the United States have created a wide diversity of estates in land, each having its own idiosyncrasies. In addition, the lands in public ownership are subject to daily changes in the applicability of the various public land laws, including the mining laws, by virtue of congressional and administrative withdrawals. It is therefore impossible to publish an accurate statewide land status map that would not be obsolete almost immediately. By following the procedures outlined below, however, a reasonably accurate determination of status can be obtained.

A breccia pipe is a vertical, pipe-like mass of broken rock (breccia), typically a few tens of meters across and hundreds of meters in vertical extent. Breccia pipes formed within Paleozoic and Triassic strata over a broad area around the Grand Canyon, and some contain high-grade uranium ore (Wenrich and Titley, 2008). They were created when groundwater (possibly basin brines), flowing through Redwall Limestone dissolution breccias and along fracture zones, dissolved more limestone, causing collapse of overlying rocks and possibly creating sink holes. Some pipes extend many hundreds of meters upward into the Chinle Group (formerly Chinle Formation; Heckert and Lucas, 2003), indicating that some pipes are at least as young as this Upper Triassic rock unit (Brown and Billingsley, 2010). Some pipes are blind and never broke through to the surface. Breccia pipes are abundant in the Grand Canyon region, with at least 1300 pipes or suspected pipes identified (Sutphin and Wenrich, 1989; Brown and Billingsley, 2010). These breccia pipes have been of interest both for their economic value and because they are adjacent to Grand Canyon National Park and the Colorado River (Spencer and Wenrich, 2013).

County geologic map of Mohave County. Map scale 1:375,000. Contour interval is 500 feet.

To most geologists, geologic maps are the single most useful type of information for understanding the geology of the land surface. As a result, geologic mapping has a long history, with over two thousand geologic maps produced in Arizona since about 1900. This index identifies only those maps that are available from the Arizona Geological Survey through the online Document Repository (http://repository.azgs.az.gov/). Approximately 720 maps of various areas within Arizona are available from approximately 500 publications. The Geologic Map of Arizona (2000) (Fig. 1) is used as background to the map indexes. Figures 2 and 3 identify regional maps with scale ranging from 1:100,000 to 1:1,000,000. Figures 4-10 identify detailed geologic maps with scale ranging from 1:200 to 1:99,000. Each of these maps is labeled with a publication number, for example “OFR 95-1”. The map indexes are followed by a list of citations to the maps that is organized alphabetically by publication number (pubNum). Generally, a user of this index would locate an area of interest on a map index, identify the publication numbers for maps in the area of interest, and then find the relevant citation or citations. With the citations one can then retrieve the desired maps from the document repository at the Arizona Geological Survey web site (repository.azgs.az.gov).

A county-by-county listing of offices concerned with mining and mineral resources in Arizona.