About 65 million years ago, an asteroid or comet crashed into a shallow sea near what is now the Yucatán Peninsula of Mexico. The resulting firestorm and global dust cloud caused the extinction of many land plants and large animals, including most of the dinosaurs.
Today at the American Geophysical Union (AGU) meeting in San Francisco, Monterey Bay Aquarium Research Institute (MBARI) researchers are presenting evidence from a mapping expedition aboard Falkor that suggests remnants from this devastating impact are exposed along the Campeche Escarpment–an immense underwater cliff in the southern Gulf of Mexico.
The ancient meteorite impact created a huge crater, over 160 kilometers across. Unfortunately for geologists, this crater is almost invisible today, buried under hundreds of meters of debris and almost a kilometer of seafloor sediment. Although fallout from the impact has been found in rocks around the world, surprisingly little research has been done on the rocks close to the impact site, in part because they are so deeply buried. All existing samples of impact deposits close to the crater have come from deep boreholes drilled on the Yucatán Peninsula.
In March 2013, an international team of researchers led by Charlie Paull of MBARI created the first detailed map of the Campeche Escarpment. The work was completed as part of a collaboration with Schmidt Ocean Institute that allowed he and his team access to the institute’s research vessel, Falkor, and its multi-beam sonar system. Paull’s proposal to work aboard Falkor was selected using a peer review process, including evaluation of the project’s intrinsic scientific and how well it aligns with the Schmidt Ocean Institute mission to advance the understanding of the oceans through effective use of innovative technologies and open sharing of resulting information. In keeping with that mission, maps resulting from the expedition have recently been incorporated into Google Maps and Google Earth for viewing by researchers and the general public.
Paull had long suspected that rocks associated with the impact might be exposed along the Campeche Escarpment, a 600-kilometer long underwater cliff just northwest of the Yucatán Peninsula. Nearly 4,000 meters tall, the Campeche Escarpment is one of the steepest and tallest underwater features on Earth. It is comparable to one wall of the Grand Canyon—except that it lies thousands of meters beneath the sea.
As in the walls of the Grand Canyon, sedimentary rock layers exposed on the face of the Campeche Escarpment provide a sequential record of the events that have occurred over millions of years. Based on the new maps, Paull believes that rocks formed before, during, and after the impact are all exposed along different parts of this underwater cliff.
Next step: Underwater fieldwork
Just as a geologist can walk the Grand Canyon, mapping layers of rock and collecting rock samples, Paull hopes to one day collect samples and do geologic “fieldwork” along the Campeche Escarpment. The newly created maps of the Campeche Escarpment could open a new chapter in such research about one of the largest extinction events in Earth’s history. Already researchers from other institutions are using these maps to plan ocean research in this little-known area. Detailed analysis of the bathymetric data and eventual fieldwork on the escarpment will reveal new clues about what happened during the massive impact event that ended the age of the dinosaurs—clues that have been hidden beneath the waves for 65 million years.
In addition to the Schmidt Ocean Institute, Paull’s collaborators included Jaime Urrutia Fucugauchi from the Universidad Autónoma de Mexico and Mario Rebolledo-Vieyra of the Centro de Investigación Científica de Yucatán. He also worked closely with his MBARI colleagues, including geophysicist and software engineer Dave Caress, who is an expert on processing multibeam sonar data, and geologist Roberto Gwiazda, who served as project manager and who described the research at the AGU meeting.