"It would've been a huge splash," said David A. Kring, a Houston-based crater expert at the Lunar and Planetary Institute, who reviewed the report but was not a part of the study.
The bay crater is the largest in the United States and by some estimates the sixth-largest in the world.
The meteorite that formed it helped shape the bay, continues to affect water supplies in surrounding Virginia communities and is used by teachers in Maryland and elsewhere to spark interest in geology.
"It's very exciting stuff," said Rachel Burks, a geology professor who lectures on the crater to students at Towson University.
The $1.5 million drilling project confirmed that the meteorite's impact created a "sterilizing pulse" that wiped out most of the microbial life at depths below 2,600 feet, said Mary Voytek, a USGS biologist.
Nutrients created by animals and plants wiped out by the blast were washed down into a cavity formed by the impact. Shock waves from the impact created pore-filled rock and sediments, Voytek said. The result: nooks and crannies at depths below 4,600 feet that harbor more mysterious microscopic organisms than anyone expected.
"What happened is, you've created a nice little incubator for life," she said.
The researchers had planned to drill 7,200 feet. But a huge granite slab, dislodged by the impact 35 million years ago, limited their progress to a little over a mile, roughly 1,400 feet short of the goal.
"Ideally we would've wanted to go deeper, and if we hadn't had to slow down, we would have," Gohn said.
Researchers say impact craters can reveal clues about prehistoric conditions that spawned some of the earliest forms of life on Earth. Drilling can shed light on the size of the meteorite, how hard it struck and what it did to the planet, scientists say.
"What is the consequence of a meteor impact? Does it sterilize the crater area and, if it sterilizes things, how quickly do microorganisms repopulate the crater fill material?" said David Vanko, a geology professor at Towson University.
Vanko, who helped collect and classify core samples, plans to publish findings next year on the heat and geothermal energy from the impact, based on analyses of melted and crystalline rocks.
Prehistoric Eearth was probably pelted by millions of meteorites, said Kring, of the Lunar and Planetary Institute. He oversaw drilling in 2001 into the Yucatan peninsula crater, where scientists believe a meteorite struck 65 million years ago, leading to dinosaurs' extinction
For corroboration, he and others look to the moon, where evidence of up to 400,000 impacts is visible on the surface.
But researchers have discovered only 170 craters on Eearth because the planet's surface is continuously being churned up by plate tectonics, erosion and other geologic and climatic conditions, Kring said.
Scientists spent 21/2 months drilling into the Yucatan crater - and then spent six years studying the core material, he said.
dennis.obrien@baltsun.com
