Magazine article Science News

Hills Point to Catastrophic Ice Age Floods

Magazine article Science News

Hills Point to Catastrophic Ice Age Floods

Article excerpt

Hills point to catastrophic Ice Age floods

Fields of low hills that cover parts of inland Canada and the northern United States may seem quite distant from the watery world of Atlantis. Yet a Canadian geologist proposes these hills formed from huge Ice Age floods that sharply raised global sea levels and could have spawned myths of a swamped continent.

"There's nothing in recorded history that matches the size of these floods," says John Shaw of Queen's University in Kingston, Ontario, who has estimated the extent of the floods from the size of the ridges.

Called drumlins--a word derived from Old Irish -- these hills appear in concentrated fields in North America, Scandinavia, Britain and other areas once covered by ice. When seen from above, the aligned knolls sometimes look like a basket of eggs lying on their sides and pointing in the same direction. Some drumlins are made of sediments deposited onto bedrock; others are ridges carved out of the rock.

Most geologists believe drumlins developed gradually from the grinding action of heavy ice sheets as they moved over the land. But in the last several years, Shaw and others have proposed the controversial idea that floods of water flowing beneath the ice created many of the North American drumlins and possibly others around the world. They base this hypothesis on the shapes drumlins share with other land forms sculpted by meltwater.

According to Shaw, heat from the Earth formed huge lakes of meltwater that remained trapped beneath the North American ice sheet. As the sheet began to retreat near the end of the glacial age, the water broke through and flowed in torrents down to the Gulf of Mexico and Atlantic Ocean. While flowing under the ice cap, water would have surged in vast, turbulent sheets that sculpted and scoured drumlins. …

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