A Trip in Time: Volcanoes in Texas!
In my previous blog on the geological story of Texas, Dinosaurs and Sea Creatures in Texas, I took a brief foray into exploring the fossil record. I was amazed to learn about the dinosaurs that once roamed the state and the massive ocean teeming with life that once covered much of what is now dry (okay, very dry) land. But there is still much more to read in that record, and it is a story that is punctuated by incredible changes in the landscape and violent volcanic eruptions.
Imagine you are driving south from Alpine, Texas on State Highway 90, going towards Marfa. Just a country road like any other? No, in fact, you are driving over the collapsed crater of the Paisano volcano. There’s even a rest area along the way where you and your family can park and read more about volcanoes in Texas. The Big Bend Snapshot of History Project has a QR code available onsite. If you scan it, you can access animations that depict what happened long ago on the very ground you’re standing on, along with recent videos of modern volcanic activity.
As you watch the modern-day videos of volcanoes erupting, lava flow, magma, and ash clouds, it is astounding to imagine that those very same events—hundreds of them—took place all over the state of Texas. Watching it is amazing when you realize that without the buffer of time, your experience on that square of earth would have been quite different.
The tectonic plates were also crashing into one another, the oceanic plate forcing itself under the continental plate, and that really got things going. When shifts like these occur, water comes along for the ride, and that’s where volcanic activity begins.
How does water make the difference? Water destabilizes everything by lowering the melting point of rocks, and that creates magma. Magma is the term for melted and semi-melted rock. The more rocks melt, the more they expand, pushing the earth’s crust up from underneath with extraordinary force. Magma can reach temperatures between 1,292 degrees Fahrenheit and 2,372 degrees Fahrenheit. The hotter the magma, the more it expands, and the greater the pressure on the volume of magma that must find a way out.
As anyone who’s ever dug a hole in Texas can attest, the ground here is heavy and hard. How much pressure coming up from beneath the earth’s crust would it take to force the ground to rise over 2,000 feet? How much energy and brute force? And yet, that is exactly what happened at the Paisano volcano.
But volcanic activity in Texas got even more powerful than that. The largest and most cataclysmic event happened in far southwest Texas, in what is now known as the Chinati mountains. The remains are there for folks to see, in a place called Mitchell Mesa Tuff. What looks now to be a beautiful and dramatic cliff face above a desert plain was once a volcanic giant. It is humbling to contemplate that, had any of us been present the day this giant blew, we would have been vaporized instantly. It buried thousands of square miles of Texas under hundreds of feet of ash and left a 240-square-mile hole in the ground.
In contrast, the explosion of Mount St. Helens in 1980 left a crater one mile wide by two miles long. Some of us were alive to see that eruption, and we were glued to our televisions as we watched a natural force so epic and frightening it captivated the nation. The Mitchell Mesa event makes the 1980 volcano look like a test run in miniature. Most of us simply can’t imagine that much raw power in nature, and what it would mean to all life forms if an event of that scale took place now.
Some of the best places to view the story in the rocks are road cuts—passages where roads have been cut through uneven terrain, exposing the inside of a hill or mountain. There is spectacular evidence of the volcanic history of west Texas around Alpine, Fort Davis, and around Big Bend. When we get curious about what the land around us has to tell us, it really is one of the most enjoyable (and accessible) forms of time travel.
If you would like to learn more about volcanoes in Texas, here are links to some helpful references:
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