Arizona Geological Survey

The documents listed below were authored by the Arizona Geological Survey.

This geologic map was produced to compile and reinterpret published geologic information, and present the result of new geologic mapping in the Ray-Superior area. This data set serves as the basis for ongoing efforts to better understand the geologic history of this area, particularly with respect to the distribution and origin of mineral deposits.

Have earthquakes strong enough to rupture the ground surface occurred on faults in central Arizona during the recent geologic past? Could such earthquakes happen in the future? If so, where are they most likely to occur? The Seismotectonics and Geophysics Section of the U.S. Bureau of Reclamation has, during the last 6 years, been working on answering these questions

Horseshoe and Bartlett Dams are located In the Transition Zone of central Arizona. Within this province, faults with evidence of Quaternary activity are widely scattered, and selsmiclty Is low In comparison to other parts of the western United States. However, most of the known or suspected Quaternary faults and most of the historic selsmlclty In Arizona occur within or adjacent to the Transition Zone.

The Mogollon (muh-ge-own) Escarpment of central Arizona is one of the State's spectacular natural attractions, especially when viewed from the rim of its precipitate cliffs.

This report presents an assessment of the seismic hazard associated with the Sugarloaf fault, which crosses State Route (SR) 87 near Mesquite Wash in central Arizona. The Sugarloaf fault is a 20 km (12 mile) long, northwest- to north-trending normal fault with displacement down to the east. We conducted a multi-faceted investigation in order to evaluate the late Quaternary behavior of the Sugarloaf fault and assess the seismic hazard associated with it.

This report presents the results of a reconnaissance analysis of Quaternary faulting in central Arizona, conducted for the U.S. Bureau of Reclamation. The goal of this study has been to thoroughly delineate locations of possible Quaternary faulting in the area surrounding existing and potential dam sites in central Arizona.

Probable quaternary faults in Arizona have been mapped by systematic interpretation of aerial photographs, extensive geomorphic field studies, and compilation of previous work. Greatest concentrations of late Quaternary normal faults are found near the Colorado Plateau margin in northwestern and north-central Arizona, with lesser concentrations in central and southeastern Arizona and the Lake Mead area. Late Quaternary faults are rare in southwestern Arizona and none have been recognized in the interior of the Colorado Plateau province in northeastern Arizona.

The Tucson 1 ° X 2.0 quadrangle exhibits a wide variety of basin landforms and late Cenozoic surficial geologic deposits. Several factors contribute to this diversity. The Tucson quadrangle spans the transition between the relatively low ranges and typically undissected basins of south-central Arizona and the higher ranges and typically dissected basins of southeastern Arizona.

This report is a compilation of available data on Quaternary faults in Arizona as of the summer of 1998. These data were compiled as part of a effort to compile data and map information on Quaternary faults throughout the world, which is being overseen by Michael Machette of the U.S. Geological Survey.

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EIS Status Update - March 2019

Screenshot of EIS Status Update document cover

Information on the forthcoming Draft EIS is now available under the ‘EIS Info’ tab. To view the update, click here.

EIS Timeline - Feb 2019

  1. Proponent submits revised Plan of Operations [Sep 2014]
  2. Federal Register Notice of Intent to prepare EIS [Mar 2016]
  3. Public scoping period and scoping meetings
    [5 meetings between Mar-Jun 2016; comment period extended from 60 days to 120 days, closed Jul 18, 2016 ]
  4. Compile and review existing data
  5. Prepare project description and identify project alternatives
  6. Publish Alternatives Evaluation Report [Sep 2017]
  7. We Are Here
    Validate Baseline Information; analyze environmental effects
  8. Prepare Draft EIS
  9. Federal Register Notice of Availability of Draft EIS
  10. 90-day public review and comment period, with public meetings
  11. Respond to public comments and prepare Final EIS
  12. Federal Register Notice of Availability of Final EIS and Draft ROD
  13. 45-day Public Objection Period
  14. Resolve objections to Final EIS and draft ROD
  15. Issue Final Record of Decision

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Forest Points of Contact

Media & General Info
John Scaggs
jscaggs@fs.fed.us

Project Manager
Resolution Copper
Mary Rasmussen
mcrasmussen@fs.fed.us

Apache Leap Special Management Area
Apache Leap SMA website