Ask a Geologist Common Q&A
How was thumb Butte in Prescott Arizona formed? I've heard it's from a volcanic plug but I've also heard speculation against that. Do you have any scientific opinions? Jenna
According to Prof. Beth Boyd, Yavapai College, Thumb Butte is an outcrop of volcanic rock that formed about 14.8 million years ago. That puts it in-place at the time of formation of the Hickey Formation, which comprises mostly basaltic lava flows and vent. Thumb Butte is made up of latite - a volcanic rock with alkali feldspar, plagioclase and a low volume of quartz. Thumb Butte looks like a volcanic neck, but there is evidence to suggest that it is simply a thick pile volcanic lava.
My husband and I made a discovery of a new mineral and was wondering how to go about having it named. Penny
Penny, According to the Mineralogical Society of America, about 4,000 minerals have been identified, with 30 to 50 new minerals discovered each year. The International Mineral Association keeps a running list of minerals.
Establishing a new, previously unidentified mineral is not a simple task and requires high precision microscopic analysis, geochemistry, and optical measurements. Naming a new mineral requires addressing the the International Mineralogical Association – Commission on New Minerals, Nomenclature and Classification protocols. Have a look at their 'A new mineral! What to do? webpage.
I hope this helps. MC
Do you have plans to expand your Holocene river mapping project to the Salt, Gila and Santa Cruz Rivers? Kay
Kay, Not at this time. Several years ago the Arizona Dept. of Water Resources contracted with us for mapping Holocene (past 10,000 years) deposits along the San Pedro and Verde Rivers and their major tributaries.
That work resulted in several geological products - maps and reports - available for all to download at the AZGS Document Repository.
- Mapping of Holocene River Alluvium along the San Pedro River, Aravaipa Creek, and Babocomari River, Southeastern Arizona: Arizona Geological Survey Digital Map - River Alluvium Map 01 (DM-RM-01), map scale 1:24,000.
- Mapping of Holocene River Alluvium along the Verde River, Central Arizona, Arizona Geological Survey Digital Map - River Alluvium 02 (DM-RM-02), map scale 1:24,000.
- Mapping of Holocene River Alluvium along Oak Creek, Wet Beaver Creek, West Clear Creek, Fossil Creek, and the East Verde River, Central Arizona: Arizona Geological Survey Digital Map - River Map 03 (DM-RM-03), map scale 1:24,000.
Does anyone have a generalized subsurface profile of the basin-range province, and specifically Arizona? Curtis
Curtis, There are a number of generalized Basin & Range models that crop up during a google search. Bob Scarborough, formally of AZGS, published a suite of detailed Basin and Range cross sections in 1985. The 20+ cross sections and short report are available here, Geologic cross sections of western Arizona Basin and Range, with accompanying geologic maps and other information. You might start with Plate 4; plate 3 superposed the cross section lines on a map of Arizona.
For a cross-section from the Baboquivari Mtns to the Transition Zone near Safford Basin, see Arca's Geologic map from the Baboquivari Mtns to the Transition Zone of the Colorado Plateau.
How can I determine whether I own the mineral rights to my property? Ed
Ed, Determining mineral rights can prove difficult. As land ownership is transferred, it is frequently unclear who owns the mineral rights. Attorney John Lacy published the 'Manual for Determination of Status and Ownership; Arizona Mineral and Water Rights' with the Arizona Dept. of Mines and Mineral Resources in 1999, revised most recently in 2010. You should probably start there.
Can you provide Information on a volcanic cone in Prescott Valley, Arizona called Gllasford Hill? In appearance it is a mini Mt. Saint Helens with a blown out East side and a small resurgent dome near the top center. What was the last estimated eruption? There is a large excavation for a Walmart on the South side that exposed what looks like pyroclastic flow material.
Glassford Hill is a cinder cone - the most common of volcanoes. It's surrounded by basaltic lava flows that probably erupted during the final stage of eruption at Glassford Hill. This volcano is about 12-million years old. The breach to the east is probably erosional in nature.
At the nearby Walmart, they are probably quarrying cinders, which are pyroclastics, or even fragmented basalt.
Thanks for the question.
Hello! I am leading a Caltech geology field trip to central Arizona May 17-20, and wanted to know if your staff know a good place to take a class out to see a good section of Peach Springs Tuff in outcrop near Kingman. We will be a bit pressed for time on that day so we'd like it to be a roadside sort of stop that doesn't require a hike to get to.
I was also thinking of possibly leading the group through Oatman to talk about the Silver Creek Caldera/area mining history, so would be interested in hearing any recommendations your staff might have on stops to discuss the geology of that area.
I think we can help. AZGS geologist Charles Ferguson is the guy to talk to. Charles first identified the Silver Creek Caldera and its relationship to the Peach Spring Tuff. He's led several field trips to the area and can advise you.
You can find mapping released in Dec. 2017, Geologic map of the Oatman 7 ½' Quadrangle, Mohave County, Arizona, at http://repository.azgs.az.gov/uri_gin/azgs/dlio/1737
Are there earth fissures south of Arizona City of southern Pinal County?
There are several earth fissure study areas south of Arizona City in southern Pinal County, including: Greene Reservoir, Tator Hills, and Friendly Quarters.
To view these and the other 23 fissure study areas in Cochise, La Paz, and Cochise Counties - visit the Natural Hazards in Arizona viewer: http://data.azgs.az.gov/hazard-viewer/
I live here in Tucson AZ. I have a father in law who is a gigantic rock hound. Now it seems my daughter, who is 8, has been bitten by the rock bug. Later this month my father in law is coming out to visit and I would love to know of some great places near Tucson to find some awesome rocks that we can hike to and get. Any rock doesn't matter whether its crystals, gold. or anything my daughter and father in law could enjoy. Thanks so much for your time.
I think I can help. We have published several free-to-download popular geology booklets on rocks of the Santa Catalina, Rincon and Tucson Mountains. These include illustrations, descriptions and maps showing where the rocks are exposed.
In terms of collecting rocks, US National Forest lands are fair game, but National Parks, National Monuments and State Parks are off limits.
- A Guide to the Geology of the Santa Catalina Mountains, Arizona: The Geology and Life Zones of a Madrean Sky Island. http://repository.azgs.az.gov/uri_gin/azgs/dlio/1679
- A Guide to the Geology of Saguaro National Park http://repository.azgs.az.gov/uri_gin/azgs/dlio/1525
- A Guide to the Geology of Sabinho Canyon and the Catalina Highway.
- A Guide to the Geology of Catalina State Park and the Western Santa Catalina Mountains. http://repository.azgs.az.gov/uri_gin/azgs/dlio/1453
There is a small dam at the foot of Sabino Creek that is backfilled with pebbles and sands from the Santa Catalina mountains. People frequently pan for 'desert rubies' there; desert rubies are really red garnet that weather out of some intrusive igneous rocks exposed in the Santa Catalina Mtns.
A few weeks back I was out on a trail ride and had stopped for a break. During that break I started to explore the landscape and stumbled upon what I thought was a large piece of coal. I went to go pick it up and quickly realized it was anything but coal, I was curious how to have someone identify what exactly I have?
This is slag, a residual product of smelting copper ore. It’s is rich in iron so it might be magnetic. The vesicles – little holes – are left as gas (H2O) escapes the melt. The slag cools quickly leaving this glassy byproduct.