Ask a Geologist Common Q&A
Good day, I stumbled across an interesting weathering pattern in some of the sandstone along the West Fork trail of Oak Creek earlier and I'm curious about what caused it. It looks like honeycomb weathering but it's isolated to a pretty small area at the bottom of a cliff overhang and from my understanding this type of erosion is only caused by salt exposure. Anyways I'm just curious what could have caused this.
There are two possible solutions (forgive the pun). Case hardening - where an amorphous silica gel precipitates locally resulting in areas of greater or lesser competency. In other words, the rock mantled by the silica gel is harder and more difficult to erode.Alternatively, fractures (joints) in the sandstone will provide a conduit for naturally acidic waters to percolate through the rock. When those waters encounter lower permeability layers, the water seeps out of the rock causing local, lateral erosion resulting in alcoves as shown below.
For illustrations and more detailed descriptions, download John Bezy’s 44-page “A guide to the Geology of the Sedona & Oak Creek Canyon area, Arizona’. (Free to download) Case hardening and alcove formation are explained on page 29 and 30 respectively.
Great question, thanks! Mike
Do you have access to the data that could make a map of US geothermal wells and their types? (not just plants but physical wells). Connor
That data should be available through the National Geothermal Data System (NGDS) that AZGS and our partners AASG, USGS, SMU, among others, build in 2010-2014 http://geothermaldata.org/. There are about 10 million data objects in the NGDS including geothermal-related data from all 50 states.
Let me know if you are having trouble compiling those data. There are still one or two individuals around who designed the data structure and they may have ideas for teasing out that data.
I have contacted the recorder’s office at Pinal and Gila counties to see if they have the claim maps for given Township-Range-Sections but I have not received confirmation on this. I used the US BLM LR2000 system on-line to get the name of claims for a given T-R-S but the system does not provide the geometry and map of these claims.
Do you know where I can get the claim maps either on-line or in a hard-copy book to determine the exact layout of the claims within a Section?
BLM should have the info; they replaced the LR2000 site, but it is not as robust. You need to call or e-mail BLM office in Phoenix: 602.417.9200 or email@example.com They should have the data you are looking for.
Good luck with it.
We had a lot of rain in Laveen AZ 85339 last week. My husband noticed a sunk-in area on our front lawn. At least two to three foot around and about a foot or less deep. The lawn was not washed away. It is just sunk in. Husband stepped in it and nothing happened. Not what I would have done. Do we need to be concerned? Do we need to call anyone to check it out? Sherry
Examining Google Earth imagery, it appears that Laveen Village is built on former agricultural fields northwest of South Mountain. Frequently, agriculture fields are poorly compacted during residential construction. As a result local sag features are not terribly uncommon.
For another viewpoint, you might reach out to NCRS - Natural Resource Conservation Service - in the PHX area. Soils are what they do and they may have further insight to share.
For inquiries: AZinfo@nrcs.usda.gov Phone: (602) 280-8808
Is a groundwater contour map plotted on a topographic map or a plain or tracing paper. OR
There are several different ways to show groundwater contours. Have a look at the URLs below for a range of treatments. Good luck with it. Mike
Depth to Groundwater map - Tucson AZ https://www.tucsonaz.gov/water/groundwater-maps
Groundwater elevation map - Tucson AZ same URL
Topo-Groundwater Contour Map - http://www.gly.uga.edu/railsback/1121GWMap3.jpeg
This site is designed for students and some excellent graphics: http://www.gly.uga.edu/railsback/GeologicalDiagrams2.html See the groundwater section.
How can you differentiate an earth fissure from damage due to being in a flood zone?
Good question. Earth fissures tend to be curvilinear and frequently cut across drainages and erosional features. Also, a gully floor typically is graded downslope; fissures frequently are not so well graded and include local depressions where water pools. Have a look at some of our fissure pictures at our AZGS photo gallery (http://azgs.arizona.edu/azgs-photo-tags/earth-fissure)
I can't tell from your image, but it does look like a local erosional feature, which tend to follow local drainages. Let me know if I can help further.
All mapped earth fissures in Arizona are displayed at the Natural Hazards in Arizona Viewer. Check it out at: http://uagis.maps.arcgis.com/apps/webappviewer/index.html?id=98729f76e46...
I found these rocks with what appears to be sea shell fossils while digging in my yard. They were at a depth of two feet. Are they rare and what should I do with them?
Glenn, They look like stream-rounded fossil-bearing (fossiliferous) limestones. These sorts of rocks are pretty common in the western and Midwest U.S. and elsewhere in the world. They are attractive but I don't believe they have any economic value.
The ground outside my home has a number of small depressions. I've filled several with dirt and they continue to recur.
We have had a number of calls and e-mail about small depressions (measured in inches or tens of inches) in Phoenix, Tucson and elsewhere in Arizona.
For the most part these are probably minor problems associated with local 'collapsing soils' where the soil is not well compacted. Small voids may exist in the shallow subsurface and over time the voids collapse resulting in localized collapse at the surface. This can happen in former agricultural lands as well.
Two things to do:
1) See our Down-To-Earth booklet: A Home Buyer's Guide to Geologic Hazards in Arizona pages 11 – 15 on problem soils.
2) Contact your local Natural Resources Conservation Service office - a federal agency that specializes in soils.
> In Phoenix: 230 N. First Avenue, Suite 509 ( (602) 280-8808 )
> In Tucson: NRCS - 2000 E Allen Rd, Tucson, AZ 85719 ( 520.670.6602 )
Good luck with it.
What type of minerals are available to the public for collecting and where do I find any near Payson Az? Denise
On Federal lands, BLM, US Forest Service, you can collect any and all minerals. There are some limitation on collecting fossils and you would need to contact BLM about that.
Arizona State Trust Lands are off limits to collecting unless you have a permit.
Payson is surrounded by the Tonto National Forest, so there are plenty of places to hunt for minerals. For details of land management status, see AZ State Land Dept http://gis.azland.gov/webapps/parcel/ . Be sure to turn on the Land Ownership layer.
The interactive Geologic Map of Arizona can provide basic information on the rocks and minerals in the Payson area; I captured a snippet of the map below. http://data.azgs.az.gov/geologic-map-of-arizona/#
Hi! My name is Nicholas. I am currently going to Middle School in Glendale AZ. I am doing a powerpoint on geologists and I had a couple of questions that I would like to be answered.
1. What age did you become a geologist?
2. What made you interested in geology?
3. What is your favorite part about geology?
4. What has been your favorite discovery (if any?) 5. What is your favorite mineral?
Happy to help:
1. What age did you become a geologist? 27 years old
2. What made you interested in geology? I really enjoyed the physical processes, such as volcanism, that impact and sculpt the Earth's surface.
3. What is your favorite part about geology? Physical volcanology and talking to people about geologic features and processes.
4. What has been your favorite discovery (if any?) Some work I did published on the frequency of cinder cone emplacement in Arizona's San Francisco volcanic field.
5. What is your favorite mineral? That a tough call. I like hornblende, plagioclase (anorthoclase) and tourmaline.