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ECOSYSTEMS > COASTAL WATERS > CONTINENTAL SHELF
Imagine finding a mammoth tooth hidden in the sediment deep below the surface of the sea. Believe it or not, scientists have made similar discoveries. But how could this happen?
Although most of the continental shelf is now submerged, it wasn’t always. As recently as 18,000 years ago, at the height of the Pleistocene Era, much of Earth’s water was trapped in massive ice floes and glaciers. Less liquid water meant a shallower ocean — perhaps as much as 300 feet (91 m) lower than today! Huge swathes of the shelf were actually dry land during this era, some regions covered in ice, others supporting everything from forests to grasslands to deserts. More dry land may have helped facilitate the movement of species between the continents, and many scientist believe this type of “land bridge” was the route used by early humans to reach North America from Asia.
As the world warmed and the ice began to melt, the ocean levels rose worldwide. Those exposed areas of the shelf were immersed in the rising water and eventually disappeared altogether. But trapped in the sediment of these submerged areas were the remnants from when they were dry land — remnants which included the fossilized remains of Pleistocene animals such as mammoths.
Related Features: Going, Going, Gone: Missing Animals of the Columbia River Gorge
Imagine finding a mammoth tooth hidden in the sediment deep below the surface of the sea. Believe it or not, scientists have made similar discoveries. But how could this happen?
Although most of the continental shelf is now submerged, it wasn’t always. As recently as 18,000 years ago, at the height of the Pleistocene Era, much of Earth’s water was trapped in massive ice floes and glaciers. Less liquid water meant a shallower ocean — perhaps as much as 300 feet (91 m) lower than today! Huge swathes of the shelf were actually dry land during this era, some regions covered in ice, others supporting everything from forests to grasslands to deserts. More dry land may have helped facilitate the movement of species between the continents, and many scientist believe this type of “land bridge” was the route used by early humans to reach North America from Asia.
As the world warmed and the ice began to melt, the ocean levels rose worldwide. Those exposed areas of the shelf were immersed in the rising water and eventually disappeared altogether. But trapped in the sediment of these submerged areas were the remnants from when they were dry land — remnants which included the fossilized remains of Pleistocene animals such as mammoths.
Related Features: Going, Going, Gone: Missing Animals of the Columbia River Gorge
