Chixculub: giant tsunami ripples found (Introduction)

by David Turell , Tuesday, July 13, 2021, 14:57 (1020 days ago) @ David Turell

Digging down to the layer found it:

https://www.sciencemag.org/news/2021/07/giant-tsunami-dino-killing-asteroid-impact-reve...

"When a giant space rock struck the waters near Mexico’s Yucatán Peninsula 66 million years ago, it sent up a blanket of dust that blotted out the Sun for years, sending temperatures plummeting and killing off the dinosaurs. The impact also generated a tsunami in the Gulf of Mexico that some modelers believe sent an initial tidal wave up to 1500 meters (or nearly 1 mile) high crashing into North America, one that was followed by smaller pulses. Now, for the first time, scientists have discovered fossilized megaripples from this tsunami buried in sediments in what is now central Louisiana.

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"To look for ancient buried structures, researchers rely on seismic imaging techniques to “see” underground. They set off explosives or use industrial hammers to send seismic waves into the earth, and listen for reflections from the layers of sediment and rock below. Companies use the technique to search for oil and gas, and they have mountains of data—especially in areas such as the Gulf of Mexico.

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"When Kinsland and his colleagues analyzed a layer about 1500 meters underground—one associated with the time of the impact—they saw fossilized ripples. These “megaripples” were spaced up to 1 kilometer apart and were an average of 16 meters tall, they reported in an Earth & Planetary Science Letters study posted online on 2 July.

"Kinsland believes the ripples are the imprint of the tsunami waves as they approached the shore in waters about 60 meters deep, disturbing the seafloor sediments. (Tidal waves gain their massive height only when they reach the ramp of the coastline.)

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"The discovery is the latest in a flurry of research about the Chicxulub impact, which was first hypothesized in the 1980s. Cores from the 2016 drilling expedition helped explain how the impact crater was formed and charted the disappearance and recovery of Earth’s life. In 2019, researchers reported the discovery of a fossil site in North Dakota, 3000 kilometers north of Chicxulub, that they say records the hours after the impact and includes debris swept inland from the tsunami."

Comment: Not surprising. Be sure to look at the seismic 'picture' of the giant ripples.