A blast from heaven?
Catastrophes
But Goff wrote his critique before last month's Geological Society of America meeting in Seattle, where Abbott reported her discovery. Early this year, intrigued by Bryant's book, she had pored over topographic maps of the seafloor in the region and found an apparent impact scar on the edge of the continental shelf just south of New Zealand.
When Abbott checked samples that oceanographic expeditions had scooped from the area, she found shattered minerals typical of meteor impacts. A field of tektites--globules of rock that melted and cooled in midair--spreads to the southeast of the crater just as it should from a impacter striking at a low angle from the northwest, the direction Bryant infers from the Australian tales. The crater, which Abbott calls Mahuika after a Maori fire deity, lies in a spot that would send waves against Australia at just the angle Bryant had already calculated. "It's young, almost surely less than a thousand years," she says, judging from the near absence of the sediment that normally builds up on the ocean floor.
"This is pretty exciting if the story holds up," says Steven Ward, a geophysicist at the University of California-Santa Cruz, who has a keen interest in comet and asteroid impacts. Goff agrees, but with neither a firm date for the crater nor sure evidence that cataclysmic waves hit New Zealand at the same time as it was formed, "the jury is still out," he says. Abbott hopes to settle the issue by gathering and dating samples of debris. An impact would have scattered material for hundreds of miles, creating a distinctive layer in the New Zealand soil, says Ward.
But even if a giant rock did plunge into the sea 500 years ago, it may not be enough to explain Bryant's catalog of devastation. Ward calculated that an object that leaves a 13-mile-wide crater off New Zealand might send waves washing 100 feet up the Australian coast 1,000 miles away, but not a cliff-scaling 400 feet. Bryant, however, has no doubts. "I don't like to believe it, but we had something mighty big hit out there."
Comet Or Quakes?
A comet or asteroid streaking across Australia and smashing into the ocean floor off New Zealand some 500 years ago could explain native accounts of fireballs and devastation and signs that giant tsunamis battered the coasts. Some scientists believe earthquakes generated at nearby faults and deep-sea trenches (red) are a more plausible source of the waves. But a 13-mile-wide scar--perhaps an impact crater--has just been found near the New Zealand coast.
[Map labels]
Australia
Darling River
Sydney
Jervis Bay
Wilcannia
Tasman Sea
Indian Ocean
Path of impacter?
Antarctica
New Zealand
South Island
Tapanui
North Island
Tonga-Kermadec Trench
Alpine Fault
Mahuika Crater
Wilcannia
Aborigine tales from this site describe a fireball crossing the sky.
Jervis Bay
Tsunamis may have surged 400 feet above sea level.
Tapanui
One translation of this Maori name is "big explosion".
Sources: Edward Bryant, Dallas Abbott
Graphic by Stephen Rountree--USN&WR
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