After: Downtown Above & Below Map – Office & Tunnels (https://www.downtownhouston.org/maps/?1)
I’ve worked in the oil & gas industry in Downtown Houston for over 15 years. Like many others, every day I walk through tunnels on and surrounded by lovely rocks, minerals, and fossils without a second thought. Though we may not have mountains in this part of the state, we have a stunning skyline and a tunnel system few people know about, and I will take these beauties for granted no more! After the most recent Texas Parks and Wildlife Becoming an Outdoors Woman workshop that my friend and I teach geology for twice a year, the idea of creating a downtown walking tour sparked. We enlisted a fellow geoscientist also located in Downtown Houston to join us in our quest. We found a few scattered tours and information online (referenced below), an e-book on Amazon (link below), and little else. So Katy, Christen, and I have set out twice a week to scout all of Downtown Houston on favorable days (preferably double digit temperatures) and tunnels during the summer months (or rainy days).
We’ve taken hundreds of pictures and have tried to find as many facts and best guesses as possible. If you do one of our self-guided tours on your own and find more accurate information, we’d be happy to update it here. We proudly bring to you the third of several self-guided walking tours: Teal Tunnel, which is almost exactly the same rocks featured in several of the Skyline Geology: A Self-Guided Walking Tour of Downtown Houston’s Buildings (below), so much of the information is repeated so you don’t have to go back and forth between tours/posts. There’s a condensed free PDF guide at the bottom of this post for easy printing or smart phone viewing. And if you need a super quick geology precursor, you can find that here: Geology Basics: For the Casual Observer or Amateur Enthusiast. Enjoy, fellow rock lovers!
FROM TOTAL PLAZA TO ENTERPRISE PLAZA
Flooring
Granodiorite (grey intermediate intrusive igneous)
Granodiorite (quartz 20-60% and plagioclase 65-90%) with uniform small-medium grained crystals, weathering present in different tiles
Accent
Slate (dark grey-green low grade metamorphic)
ENTERPRISE PLAZA – 1100 LOUISIANA
Flooring/Walls
Tufa (Travertine, continental sedimentary)
Travertino Romano (trade) from Tivoli near Rome in Italy
Also known as Romano Classico or Travertine Classico and Travertino Romano Antico (darker varieties)
Walls and flooring all travertine
Tufa/Travertine: formed by algae/calcium carbonate in hot springs, phytoherms (freshwater reefs) and thrombolite-stromatolites; not to be confused with tuff/tufo (igneous)
Observed: stromatolite patterns/precipitation growth dominant feature, some vugs partially to fully filled with more transparent cement
ONE ALLEN CENTER – 500 DALLAS
Flooring/Walls
Fossiliferous Limestone (light tan sedimentary)
Observed: gastropod fossils and others unidentified
Accents
Marble (brown metamorphic)
“Dirty” marble with fractures and calcite veins
Marble veins: due to various mineral impurities such as clay, silt, sand
Transition into Circular Court
Best guess: Diabase/Gabbro (dark grey-black mafic intrusive igneous)
Circular tiles diabase/gabbro containing small grained but just visible to naked eye dark minerals
Download Free PDF Tunnel Geology: A Self-Guided Walking Tour of Downtown Houston’s Buildings (Teal Loop) here: DowntownGeologyTealPDF
Published Walking Tours
Skyline Geology: A Self-Guided Walking Tour of Downtown Houston’s Buildings (City Hall Loop)
Tunnel Geology: A Self-Guided Walking Tour of Downtown Houston’s Buildings (Red Loop)
Skyline Geology: A Self-Guided Walking Tour of Downtown Houston’s Buildings (Hyatt Loop)
Tunnel Geology: A Self-Guided Walking Tour of Downtown Houston’s Buildings (Yellow Tunnel)
Skyline Geology: A Self-Guided Walking Tour of Downtown Houston’s Buildings (Jones Loop)
Tunnel Geology: A Self-Guided Walking Tour of Downtown Houston’s Buildings (Teal Tunnel)
CONTRIBUTORS
Sheila Echols-Smesny holds a Bachelor of Science in Geology from Sam Houston State University, an Executive MBA from Texas Woman’s University, and works at an oil & gas company in Houston. Red Shoes. Red Wine. is Sheila’s travel, lifestyle, & hobby blog.
Christen Peevy holds a Bachelor of Science in Geology from University of Oregon and works at an oil & gas company in Houston. Christen’s lifestyle blog is Short Sweet & Lovely.
Katy Mainwaring holds a Bachelor of Science in Geology from Texas Tech University and works at an oil & gas company in Houston. Katy teaches geology with Sheila for Texas Parks and Wildlife Becoming an Outdoors Woman program.
BEFORE YOU GO
Safety
- Look up, not at your phone, when navigating downtown
- Please be mindful of the traffic lights, pedestrian signals, bike lanes, and buses
- Buses make frequent stops and can sometimes hop curbs
- Some curbs, pavements, and streets may be uneven
Etiquette
- Please review the walking guide prior to arriving downtown to maximize time spent on the tour
- Please be mindful of downtown employees and keep slower pedestrian traffic to the right so they can go about their business
- Try to walk in pairs if walking around downtown as a group
- If approached by a homeless person, try to be firm but respectful
REFERENCES
- Houston Geological Society, 1995, Walking Tour of Downtown Houston Building Stones: Research Committee, Philip W. Porter
- Houston Gem and Mineral Society, Houston Geologic Society, 2008, Walking Tour – Houston Building Stones, Neal Immega
- Brian Allison, Earth Science Guy blog (http://mnearthscienceguy.blogspot.com/2012/07/minnesota-geology-monday-granites-of-st.html)
- United States Geological Survey: https://mrdata.usgs.gov/geology/state/map-us.html
- Wikipedia
- Geology.com
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This is such great information!
Thank you Kathy!!