The Ground Below - The Day the Earth Burned

A Deep-Time Detour: The Day Texas Was Rocked by Space

I have been running in races in Texas for about ten years now. One of the unique things about this region is its proximitiy to the single most imporrant geological adn astronomical event to occur to planet earth. Sixty-six million years ago, Earth got slammed—hard. A chunk of space rock, roughly the size of a city, came screaming in from deep space at more than 40,000 miles per hour. When it struck what’s now the Yucatán Peninsula, near the town of Chicxulub, the world changed in minutes (Alvarez et al., 1980).

This wasn’t a slow extinction. It was instant mayhem.

The asteroid released energy equivalent to a billion nuclear bombs. The crust of the Earth rippled like a fluid. Oceans boiled. Seawater flashed into steam. Pulverized rock exploded skyward in a white-hot column. The impact carved out a crater more than 110 miles wide and temporarily exposed the planet’s mantle (Hildebrand et al., 1991).

Everything nearby was obliterated in seconds. A megatsunami raced across the Gulf of Mexico, reaching the Texas coastline with walls of water hundreds of feet high. Layers of chaotic sediment—rip-up clasts, breccias, and other debris—still show up in Texas’s coastal geology (Bourgeois et al., 1988). In fact, if you're running trails near the Gulf or even through the hill country, you’re moving through landscapes shaped in the long shadow of this event.

But the destruction didn’t stop there. What followed came in waves:

Wave One: Heat and Fire

As debris launched into space, it cooled, then rained back down—billions of red-hot fragments streaking through the atmosphere. The sky glowed with enough infrared radiation to ignite global wildfires. For hours, the Earth's surface may have reached oven-like temperatures (Schulte et al., 2010).

Wave Two: Darkness and Cold

Sulfur-rich rocks—especially the limestone and gypsum of the Yucatán—vaporized in the blast, injecting massive amounts of sulfur dioxide and dust into the stratosphere. The sky went dark. Sunlight disappeared. Photosynthesis stopped. Temperatures plunged. Food webs collapsed—first in the oceans, then on land (Vellekoop et al., 2014).

Wave Three: Extinction

Within weeks, global ecosystems fell apart. Phytoplankton died, crashing marine food chains. On land, plants withered, herbivores starved, and predators followed. About 75% of all species on Earth disappeared. Ammonites, mosasaurs, pterosaurs, and all non-avian dinosaurs vanished.

But not everything died. Some mammals survived—small, burrowing omnivores that needed less food and could shelter from the chaos. Birds, the only surviving dinosaurs, also pulled through. These survivors inherited the Earth (Kring, 2007).

AAnd yes—human evolution eventually emerged from that wreckage and, in fact, was aided by it. Without dinosaurs, the dominant predators on the planet, small mammals were able to find a foothold in the surviving ecological environment.

So, why mention this during a race in Texas?

Because parts of Texas—especially around the Gulf Coast and into the hill country—hold the scars of this ancient impact. In places like San Antonio, Austin, and the coastal plains, geologists have found tsunami debris, shocked quartz (formed under intense pressure), and even microscopic glass beads called tektites, created when molten rock cooled as it rained from the sky (Bourgeois et al., 1988).

Even the region’s limestone bedrock tells part of the story. The vast marine deposits laid down in the warm Cretaceous seas were abruptly interrupted by the fallout from Chicxulub. Some of the very aquifers and sinkholes runners encounter in central Texas connect back to the ancient conditions that existed before and after the impact.

Though it’s buried under layers of younger rock and rainforest, the Chicxulub crater is one of the best-preserved large impact sites on Earth. In the 1990s, researchers using seismic data and gravity maps finally pinpointed its location. Drilling into the crater has revealed peak rings—circular mountains that formed when the crust rebounded from the shock—as well as impact melt rocks and high-pressure minerals (Hildebrand et al., 1991; Gulick et al., 2019).

One of the most surprising findings? Life came back quickly. In 2016, scientists drilling into the crater found signs of microbial life within decades of the impact. It was a reminder that even in the most devastated environments, life finds a way (Gulick et al., 2019).

But full ecological recovery took far longer. Forests needed thousands of years to return. Coral reefs rebuilt over millions. Biodiversity didn’t bounce back to pre-impact levels for tens of millions of years. That long, uneven recovery gave mammals—including our distant ancestors—the opportunity to evolve and diversify (Schulte et al., 2010).

Studying Chicxulub isn’t just about dinosaurs. It’s about contingency. It's a reminder that everything we know—every city, every trail, every breath we take—exists because a rock from space hit the Earth in the wrong place at the right time.

So if you're out there running through a patch of scrubby limestone or climbing a Texas ridge, think about this: You're moving through a landscape shaped by one of the most violent days in our planet's history. And in a very real way, you're part of the world that came after.

And yeah—those hills are steep. But at least the sky isn’t falling.

References (APA Style)

Alvarez, L. W., Alvarez, W., Asaro, F., & Michel, H. V. (1980). Extraterrestrial cause for the Cretaceous–Tertiary extinction. Science, 208(4448), 1095–1108.

Bourgeois, J., Hansen, T. A., Wiberg, P. L., & Kauffman, E. G. (1988). A tsunami deposit at the Cretaceous–Tertiary boundary in Texas. Science, 241(4865), 567–570.

Gulick, S. P. S., Morgan, J. V., Bralower, T. J., Chenot, E., Christeson, G. L., Collins, G. S., ... & Villarreal, M. N. (2019). The first day of the Cenozoic. Proceedings of the National Academy of Sciences, 116(39), 19342–19351.

Hildebrand, A. R., Penfield, G. T., Kring, D. A., Pilkington, M., Camargo, Z. A., Jacobsen, S. B., & Boynton, W. V. (1991). Chicxulub crater: A possible Cretaceous/Tertiary boundary impact crater on the Yucatán Peninsula, Mexico. Geology, 19(9), 867–871.

Kring, D. A. (2007). The Chicxulub impact event and its environmental consequences at the Cretaceous–Tertiary boundary. Paleogeography, Paleoclimatology, Paleoecology, 255(1–2), 4–19.

Schulte, P., Alegret, L., Arenillas, I., Arz, J. A., Barton, P. J., Bown, P., ... & Willumsen, P. S. (2010). The Chicxulub asteroid impact and mass extinction at the Cretaceous–Paleogene boundary. Science, 327(5970), 1214–1218.

Vellekoop, J., Smit, J., Morgans, J. V., van der Ploeg, R., Damsté, J. S. S., Schouten, S., & Speijer, R. P. (2014). Rapid short-term cooling following the Chicxulub impact at the Cretaceous–Paleogene boundary. Proceedings of the National Academy of Sciences, 111(21), 7537–7541.