Dr. Dallas Abbott
Earth Institute Contact: Dr. Dallas Abbott
Although conventional astronomy suggests that large (> 1 km) impactors hit the Earth once every 300,000 years we have assembled evidence for at least 3 large oceanic impacts during the last 11,000 years. The ~ 1.5 km “Deluge comet” produced the 29 km Burckle crater, which is astronomically estimated to be 4800 years old. This impact may be responsible for ancient legends about torrential rainfall, hurricane force winds, and coastal mega-tsunamis. The deluge was followed by a period of dim sunlight and colder climate. Around 1440±15 A.D., a ~1 km cometary impactor produced the 24 km Mahuika crater off the coast of New Zealand. This impact may have produced 130-meter tsunami runups in Jervis Bay, Australia and may have caused the Maori to move inland. We have also found a pair of craters in the Gulf of Carpentaria that are 18 and 12 km in diameter and appear to date to ~ 535±200 A.D. If so, their source bolide was over 1 km in diameter. In addition, we have candidate impact events in the Mediterranean Sea, the North Atlantic, the North Sea, off the coast of Vietnam, off the China/Korean border, on the Kerguelen Plateau, in the Caribbean, and off the coast of Denmark. The student would select one of these events to work on, depending on their interest and the availability of core samples near the crater candidate. There is a distinct possibility that the equatorial (between 30 N and 30 S) candidate impact events may be related to the climate downturns that are recorded in tree ring records. The formation of the Vietnam crater may have produced a rain of dust that is described in the Chinese historical record and is inferred to be related to a major climate downturn. There was a major historical dust veil event that lasted for 18 months during 535 and 536 A.D. that may be related to the 535 to 541 A.D. period of colder climate. Neither of these dust veil events is associated with a volcanic eruption.