The discovery

The story of the Falklands crater begins in 1991, shortly after evidence was piling up showing Chicxulub was probably the notorious dinosaur-killing impact site. Maps of Earth's gravity field there showed a circular distortion, indicating less-bulky sediment had settled in the crater since its formation.

Michael Rampino, a geologist at New York University who now also works for NASA's Goddard Space Institute in New York, started looking for similar gravity anomalies elsewhere on Earth. He reasoned that a crater associated with the Great Dying would be even larger than that of Chicxulub, and he soon found one.

"I was struck by this gravity anomaly on the Falkland plateau just to the west of the Falkland Islands," Rampino told me during a recent phone call. "It was a very nice circular well of gravity about 250 kilometers in diameter."

Rampino published his discovery in a brief abstract for the American Geophysical Union in 1992. It received modest press attention, but was soon forgotten—mainly because there was no additional evidence available to back up the finding.

"That's all the information I had," Rampino said. "I suggested that this should be looked at, with respect that it might be a buried impact crater."

It would be more than two decades before anyone was able to follow his suggestion.

The crater hunter

Maximiliano Rocca, who goes by Max, is not your typical crater hunter. Though he studied geology at the University of Buenos Aires, he never became a geologist, and instead works as a systems analyst in Buenos Aires, Argentina.

When he's not working at his day job, Rocca hunts for hidden Earth impact craters. He pores through scientific data, including gravity maps, and alerts the scientific community when he finds something interesting. Over the years, Rocca has published and co-published dozens of abstracts and papers, and presented at academic conferences.

Since 2002, The Planetary Society has funded Rocca's research through our Planetary Defense program. Rocca's unique research has paid off; most notably, in 2004, when he discovered a 50-kilometer-wide feature in Colombia now confirmed to be the largest impact crater in South America.

Rocca, who prefers to communicate via email because of spotty Internet service making Skype calls difficult, often sends multiple, exclamation point-laden emails to convey his excitement. In one such email, he told me the Colombia crater was "one of the best things I have ever done in my life."

The Falklands impact crater, if confirmed, could dwarf his Colombia find.