Publishing date: 04-26-2004 3:59 PM
(Waverly, Wisconsin-AP) -- It struck with catastrophic force about 70 miles east of what's now Minneapolis.
Scientists say a 650- to 700-foot meteorite crashed into the earth at speeds over 67,000 miles an hour, 450 (m) million years ago.
The impact dislodged rocks and created a massive hole in a four-mile area called Rock Elm in what's now western Wisconsin.
The scientists' report says the impact at Rock Elm released more than one-thousand megatons of explosive energy.
It also sent out shock waves that crushed rock in a distinctive way that researchers first noted in 1942, though the type of calamity remained a mystery until now.
Over time, shale, dirt and sediment have filled the hole to make the impact site virtually indistinguishable from the surrounding land.
The report is published in the Geological Society of America Bulletin.
Copyright 2004 by The Associated Press. All Rights Reserved.