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Arizona Geological Survey at the University of Arizona

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Arizona Geological Survey at the University of Arizona

Geosciences serving Arizona since 1888. Now at the University of Arizona's College of Science.
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The AZGS staff map and describe the bedrock and surficial geology of Arizona with emphasis on the densely populated Phoenix-Tucson urban corridor. We provide the results of our geologic investigations to those local, state, and federal governmental agencies that are responsible for prudently managing Arizona's land, water, mineral, and energy resources. Once AZGS staff has compiled geologic data f

rom the field, that information is reviewed in-house to meet publication standards. To inform the public regarding Arizona's geologic setting, we provide maps, reports, and other publications in our bookstore and in our library. More resources are available online through our web site (guess you found those already...). Other services include developing digital information resources for archiving and serving geoscience data (Arizona Geologic Information System), science outreach through the Geologic Extension Service, and maintaining a central repository for well cuttings, cores, and associated supplementary data.

08/06/2026

The ~ 400 Pleistocene-Holocene volcanoes and maars (8) of the Pinacate volcanic field straddle the Arizona-Mexico frontier. Fresh USGS research identifies three cinder cone clusters in the field. You can retrieve the report here, https://pubs.usgs.gov/publication/pp1890G

From the section, “The Pinacate Volcanic Field”: “The Quaternary Pinacate volcanic field consists of Pleistocene to recent basaltic cones and associated erupted products (lava flows and tephra; fig. 2). About 400 basaltic monogenetic vents formed atop the large shield volcano, Sierra El Pinacate (known locally, and referred to herein, as the Santa Clara shield volcano; fig. 2A), which itself formed in the late Pliocene to early Pleistocene; monogenetic vents formed in the Pleistocene to Holocene (Lynch, 1981; Gutmann and others, 2000; García- Abdeslem and Calmus, 2015). The youngest dated cones are in the eastern portion of the volcanic field, where an extensive tephra deposit blankets the landscape (fig. 2B). The reported ages indicate a late Pleistocene or younger age (less than 50 thousand years ago, or kilo- annum [ka]) for volcanic activity in this sector of the field (Zawacki and others, 2019 and references therein).)

Cover Image caption: “View looking southeast from near the MacDougal Crater (maar; lat 31°58′2.85″N., long 113°37′’49.40″W.) in the northwestern part of the Pinacate volcanic field. Other maars and smaller volcanic edifices are seen in the middle ground, in front of the main shield volcano, Sierra El Pinacate (known locally as Santa Clara). This view presents a portion of vent cluster 1, which is presented in Figure 10. Photograph by Ramon Arrowsmith, Arizona State University, taken November 2022 from an uncrewed aerial vehicle.”

Map Image: Satellite image (A) and geologic map (B) of the Pinacate volcanic field in Sonora, Mexico, and Arizona, United States (modified from Donnelly, 1974; Kunze, 2006). The main shield volcano, Sierra El Pinacate, is known locally and depicted here as the Santa Clara shield volcano. The main volcanic constructs (lava flows, cones and pyroclastic deposits) are mapped separately; the cone unit consists of cinder cones, tuff cones, and maars. Calif., California; Chih., Chihuahua; Sina., Sinaloa.

Mazzarini, F. & 5 others, 2026, Self- similar vent clustering in the Pinacate volcanic field (Sonora, Mexico and Arizona, United States), chap. G of Poland, M.P., Ort, M.H., Stovall, W.K., Vaughan, R.G., Connor, C.B., and Rumpf, M.E., eds., Distributed volcanism— Characteristics, processes, and hazards: U.S. Geological Survey Professional Paper 1890, 51 p., https://doi.org/ 10.3133/ pp1890G.

08/05/2026

What is the Mountain West Geothermal Consortium? It’s a new southwest regional enterprise focused on identifying and promoting geothermal energy to shore up America’s energy needs.

From their website at https://www.mountainwestgeo.org/about, “The Consortium is advised by next-generation geothermal developers, investors, and potential utility and hyperscaler offtakers that are starting to design and close geothermal deals in the near term.
We work in close coordination with leading NGOs and associations on their geothermal power work, including Geothermal Rising and the National Association of State Energy Officials (NASEO) Geothermal Power Accelerator.

The consortium is supported by Giving Green and other philanthropic organizations dedicated to the development of new clean, firm technologies.”

08/04/2026

The western U.S. is ablaze. According to Inciweb (inciweb.wildfire.gov), more than ~2,899,511 acres (4,530 square miles!), mostly in the western U.S., have burned over the past 7 days. The map shows approximate active wildfire locations as of 3 Aug. 2026.

Spokane, WA, has been particularly hard hit by three (3) urban-interface-wildfires. So far 10,280 acres have been torched. Hundreds of buildings have been destroyed by fire and 64,000 people evacuated.

08/03/2026

About 2.5 billion years ago, during the so-called “Great Oxidation Event(s?)”, cyanobacteria began flooding Earth’s atmosphere with oxygen. A summary of recent research into the origin of Earth’s oxygen paints a complex picture of multiple pulses of oxygen formation. Banded Iron Formations – see photo - are a product of the early oxidation events. Some researchers now think that the Snowball Earth period may have played a substantial role in early oxygen formation. From a summary in Science by Paul Voosen.

Image: Banded Iron Formation comprising alternating silica - reddish jasper, and iron oxide – hematite / magnetite (gray).
(DIRK WIERSMA/Science Source)

08/02/2026

This shaded relief map of northern Arizona illustrates prominent geologic features: the Basin & Range Province (left), the Colorado Plateau, the San Francisco and Hopi Buttes volcanic fields, and to the north, Grand Canyon and Black Mesa.

Flagstaff, Arizona, the geotourism hub of northern Arizona, is nestled in the largest continuous Ponderosa Pine Forest in North America. Ninety mile north, via US 180 and AZ 64, is Grand Canyon National Park; 30 miles (48 km) to the south on AZ 89A is the Red Rock Country of Sedona. Within a radius of ~ 40 miles of Flagstaff are more than 800 volcanoes, the youngest of which erupted in 1064 CE. Shallow escarpments evincing young and active fault systems are on prominent display as are miles-long monoclines north and northeast of Flagstaff.

The nearby Coconino and Kaibab National Forests are ideal for hiking, biking, skiing and camping. The San Francisco Peaks, the highest point in Arizona at 12,666 feet (3,860 m), offers groomed ski slopes and backcountry skiing and hiking. Three national monuments, Sunset, Walnut Canyon, and Wupatki are within an hour’s drive from the center of town.

Flagstaff is Arizona’s first International Dark Sky City and the home of America’s first science festival. This geoheritage tour profiles some of the principal geologic and archaeological sites surrounding the city.

Image: Shaded Relief map by Edwards & Batson (1991) US Geological Survey Map I-1821, Sheet 2

08/01/2026

Awesome post from our colleagues in New Mexico Bureau of Geology and Mineral Resources. Great field shots.

07/31/2026

PBot – Integrative Paleobotany Portal. A “How to Guide” for PBot is now available at AZGS digital library, https://library.azgs.arizona.edu/item/AOFR-1779824101073-907 .

From the abstract, “The Integrative Paleobotany Portal (PBot) is a free online software for fossil plant data management, analysis, and exploration. Core to the PBot mission is providing broad access to paleobotanical research tools and data and to provide an efficient pipeline for data entry that ensures that research products and data are freely available to the general public for the long term. PBot was created because plant fossils present unique challenges that are not accommodated by existing paleontological databases. Plant organs (e.g., leaves, wood, fruits, seeds) are rarely preserved attached to each other, and it can be difficult to associate different organs as part of the same plant and to assign formal taxonomic names to the isolated organs. PBot provides the necessary infrastructure and tools for researchers to record a rich array of fossil plant data and to coordinate that data across institutions, researchers, time periods, and geography.’

Citation: Currano, E.D. and 5 others, 2026, PBot: Integrative Paleobotany Portal — How To Guide. Arizona Geological Survey Open-File Report OFR-26-9, 57 p.

07/30/2026

GeoSNAPS ~ Caldera Eruption, Southeastern AZ

26.5 MYBP (million years before the present) southern Arizona was the site of a cataclysmic volcanic eruption that formed the 12-mile-wide circular Turkey Creek Caldera. As shown in this graphic, huge clouds of volcanic ash and gas belched at supersonic speeds from ring dikes along the perimeter of the formative caldera. The resulting volcanic plume rose tens of miles high before collapsing into ground-hugging, pyroclastic flows that covered large parts of southeastern Arizona and western New Mexico.

It is estimated that more than 120 cubic miles of molten rock was erupted. For more information, Guide to the Volcanic Geology of Chiricahua National Monument and Vicinity, Cochise County, Arizona, by John S. Pallister,l Edward A. du Bray, and Douglas B. Hall. The report and geologic map, including a number of field shots and colored illustrations are available online at the USGS Publication Warehouse - http://pubs.er.usgs.gov/publication/i2541

07/29/2026

Utah Geological Survey recently launched the “Utah Geothermal Network” (UGeN). From the the May 2026 UGS ‘Survey Notes’, “UGeN is a collaborative community built to connect people, projects, and ideas across Utah’s growing geothermal landscape. This non-competitive group is for researchers, professionals, students, community stakeholders, and those simply interested in Utah’s geothermal resources to share insights, spark partnerships, and turn underground potential into real-world impact. Membership is free and offers access to periodic newsletters, meetings, and events focused on advancing geothermal energy development in Utah.” For more and to register as an interested party, https://geology.utah.gov/energy-minerals/geothermal/utah-geothermal-network/

For a primer on UGeN goals and upcoming meetings, see their youtube video at https://www.youtube.com/watch?v=wNOduJONg-s .

07/28/2026

A new USGS report on post-wildfire hazards in northern California has ramifications for the arid southwestern U.S., including Arizona. The article includes suggestions on preparing for hazards in the wake of a large and damaging wildfire. You can download the research paper at https://pubs.usgs.gov/publication/sir20265029.

From the ‘Plain Language Summary’, “The 2021 Dixie Fire in northern California was one of the most destructive wildfires in California history. This report explains a workshop organized by the U.S. Geological Survey, the Postfire Hazards and Consequences Workshop, to identify the chains of effects caused by the fire and postfire conditions on the nearby people, buildings, land, and environment. The results of the workshop indicate that the wildfire led to a wide variety of negative effects that go beyond the immediate damage. The results also provide suggestions for what could be done before and after wildfires in the future to reduce the negative effects.”

Image: Debris flow deposit in the North Fork Feather River, Plumas County, California, near the Dixie burn area. Photograph by Don Lindsay, California Geological Survey.

Citation: Meldrum, J.R., Cornish, B.J., Friedman, J.R., Chiavacci, S.J., Huber, C.C., Craig, S., and Schuster, R., 2026, Cascading consequences and interventions for hazards after wildfire in northern California: U.S. Geological Survey Scientific Investigations Report 2026–5029, 21 p., https://doi.org/ 10.3133/ sir20265029.

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1955 E 6th Street
Tucson, AZ
85719

Opening Hours

Monday	8am - 5pm
Tuesday	8am - 5pm
Wednesday	8am - 5pm
Thursday	8am - 5pm
Friday	8am - 5pm

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+15206212352

Website

http://azgs.arizona.edu/

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