- Up to 50 percent of America's substrate in certain regions likely was affected by beaver activities.
- As many as 400 million beavers once inhabited North America, with the animals present in all 50 states save for Hawaii.
- Beavers help to keep drinking water safe and promote species diversity.
Beavers, once abundant and widespread in the Northern Hemisphere, helped to forge the ground underneath many Americans' feet The team behind a new study used ground-penetrating radar to detect buried beaver dams.
The study, published in the January 2012 issue of Geology, reveals how beaver activity up to thousands of years ago affected sedimentation and left its lasting mark within North America's ground.
"Ecologists have estimated that, prior to the arrival of Europeans in North America, anywhere from 60 to 400 million beavers inhabited the continent, with a geographic range estimated at 15 million square kilometers," co-author Ellen Wohl told Discovery News.
"Beavers were present from the arctic tundra to the deserts of northern Mexico, so they would have been in every U.S. state but Hawaii," added Wohl, a professor in the Warner College of Natural Resources at Colorado State University.