Hermann Bermúdez will present evidence of this "mega-earthquake" at the upcoming GSA Connects meeting in Denver this Sunday, October 9. Earlier this year, Bermúdez visited outcrops of the infamous Cretaceous-Paleogene (K-Pg) mass extinction event boundary in Texas, Alabama, and Mississippi to collect data, supplementing his previous work in Colombia and Mexico documenting evidence of the catastrophic impact.

In 2014, while doing fieldwork on Colombia's Gorgonilla Island, Bermúdez found spherule deposits—layers of sediment filled with small glass beads (as large as 1.1 mm) and shards known as "tektites" and "microtektites" that were ejected into the atmosphere during an asteroid impact. These glass beads formed when the heat and pressure of the impact melted and scattered the crust of the Earth, ejecting small, melted blobs up into the atmosphere, which then fell back to the surface as glass under the influence of gravity.

The rocks exposed on the coast of Gorgonilla Island tell a story from the bottom of the ocean—roughly 2 km down. There, about 3,000 km southwest of the site of the impact, sand, mud, and small ocean creatures were accumulating on the ocean floor when the asteroid hit. Layers of mud and sandstone as far as 10–15 meters below the sea floor experienced soft-sediment deformation that is preserved in the outcrops today, which Bermúdez attributes to the shaking from the impact.

Faults and deformation due to shaking continue up through the spherule-rich layer that was deposited post-impact, indicating that the shaking must have continued for the weeks and months it took for these finer-grained deposits to reach the ocean floor. Just above those spherule deposits, preserved fern spores signal the first recovery of plant-life after the impact.