Looking for help identifying formations in central Texas

[element_103]

Hello all, 

 

Can anyone recommend a paper, book, or website that can help me learn how to identify the formations in Texas (especially central Texas [i.e., San Antonio northeastward to Georgetown])? I am realizing more and more the utility of formation info for fossil identification as well as the scientific value such information adds to an individual's personal collection.

 

Thank you kindly in advance for your help

[Cris]

Have you see the mobile app Rockd? I highly recommend it and use it often, especially when I'm in a new area.

[DPS Ammonite]

Read the professional literature.

Check out the references in North Texas Fossils website:

https://northtexasfossils.com
 

Also use Geolex which finds references for rock units. Search for rock unit name such as Duck Creek plus Geolex.

https://ngmdb.usgs.gov/Geolex/Units/DuckCreek_8002.html

 

See this for Texas maps:

 

https://txpub.usgs.gov/txgeology/

(Thanks to John J for posting a working link to what I tried to post to.)

 

https://www.usgs.gov/centers/oklahoma-texas-water-science-center/science/texas-geology-web-map-viewer

 

 

Edited August 18, 2023 by DPS Ammonite

[JohnJ]

I use this site.

[Mikrogeophagus]

I can second @JohnJ's recommendation of the USGS pocket geology site as well as @DPS Ammonite's mention of North TX Fossils (although I will warn that the formations from that website tend to be many hours away from Central TX, so there can be some major regional variation in how each formation looks/produces). Beyond that, I would recommend familiarizing yourself with common fossils that are known to occur in your formation of interest as well as the general lithology.

[patelinho7]

I second Rockd! I love that app, but specifically so because I can confirm the accuracy and recency of the map for my area. I assume Rockd never loads poorly sourced map material to its database, but it comforts me that I have confirmed with the very person who drew up the geologic map for my area! It’s a great addition to your fossil hunting toolbox.

[element_103]

Thank you @Cris, @DPS Ammonite, @JohnJ, @EPIKLULSXDDDDD, and @patelinho7! These resources are already proving useful. Appreciate you guys big time! 

[grandpa]

A great write-up by @Uncle Siphuncle on Central Texas geology :

A Comprehensive Guide To The Cretaceous Strata Of The Greater San Antonio Area; How To Read The Rocks

can be found at

This is a wonderful resource.

---

 

 

[erose]

And read the written descriptions of the formations.  Maps are still just an approximation.  In places where. they. are stacked upon each other you will need the descriptions to recognize the formations. We are lucky that geology has been such. a big part of Texas. The Bureau of.  Economic Geology (TXBEG) has produced a. plethora of maps and papers that can be had on line or by ordering them. 

[BobWill]

18 hours ago, erose said:

And read the written descriptions of the formations.  Maps are still just an approximation.  In places where. they. are stacked upon each other you will need the descriptions to recognize the formations. We are lucky that geology has been such. a big part of Texas. The Bureau of.  Economic Geology (TXBEG) has produced a. plethora of maps and papers that can be had on line or by ordering them. 

My favorite resource can be ordered from the BEG store and includes a booklet with written descriptions of the contents of each formation. The Geologic Atlas of Texas was available for free online for a time, then removed, then put back and removed again. Digital copies may available for sale but I haven't checked recently. Some maps had the descriptions right on the map, but most were in a separate booklet which was not available online when the maps were. These 38 maps are the most detailed and accurate I have seen and the descriptions are very helpful. They each include six or more counties and you can just order the maps of the areas you collect.