‘Waterworld’ Earth preceded late rise of continents, scientist proposes
Expansion of dry land may have enabled Cambrian explosion
WATER WORLD The continents rose above sea level only a few hundred million years ago, a new proposal states. Before that time, Earth’s surface was mostly covered by water.
Tfioreze/Wikimedia Commons (CC BY-SA 3.0)
SAN FRANCISCO — Earth may have been a water world for much of its history, a new proposal contends. Just like in the Kevin Costner movie, the continents would have been mostly submerged below sea level. Previous proposals have suggested that Earth’s land area has remained comparatively unchanged throughout much of geologic time.
But geoscientist Cin-Ty Lee of Rice University in Houston proposes that Earth’s continents didn’t rise above the waves until around 700 million years ago, when the underlying mantle sufficiently cooled. Though many scientists are unconvinced, that continental rise may have contributed to the rapid diversification of life known as the Cambrian explosion. “The Earth is cooling and that actually has manifestations that dictate how life goes,” Lee said December 15 at the American Geophysical Union's fall meeting.
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