The Rheic Ocean

Posted on November 23, 2007

Globe showing the Rheic OceanAbout 430 million years ago a massive ocean called the Rheic Ocean covered much of the Earth and seperated the land masses of Laurentia and Gondwana. Ohio University geologist Damian Nance and his colleagues are trying to bring more attention to the Rheic in a new book published by the Geological Society of America called The Evolution of the Rheic Ocean.
Call it the ocean that time forgot. About 400 million years ago, the Rheic Ocean played a big role in Earth�s history. When this massive body of water closed, the Appalachians were lifted to Himalayan heights and the planet's continents slammed together to form the supercontinent of Pangaea. Dinosaurs and early mammals evolved to traverse the large swath of land, spreading life to every corner of the globe.

But the Rheic Ocean doesn't get much attention in the field of geology today. In fact, American texts give usually credit to an older ancient sea, the Iapetus, for creating the Appalachians.

Ohio University geologist Damian Nance and colleagues now hope to set the record straight with a new book published this fall by the Geological Society of America. It pulls together recent data from a team of UNESCO-funded scientists in the United States, Germany, Britain, Portugal, Turkey and several former Eastern Block countries who have spent years combing for better geological evidence of this ancient ocean and its legacy.

The Rheic Ocean opened 480 million years ago and, by 430 million years ago, separated two major land masses. To the north was Laurentia, which comprised North America, Europe, Greenland and part of Asia. To the south lay Gondwana, which comprised Africa, South America, Antarctica, Australia and India.

The sea closed some 340 million years ago, which pushed the continents together and created two mountain ranges: the Appalachian mountains of North America and the Variscan Belt of Europe, which runs across southern Europe and North Africa from Ireland to the Czech Republic and from Morocco to the Black Sea. Both mountain belts have eroded greatly over time, "shadows of their former selves," Nance noted.
The books author suggest that knowledge of oceans and continental shifts can not only help scientists better predict future geological changes but it may also help with located natural resources.

Illustration credit: Christina Ullman

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