Summary
Over time, sea levels rose and dropped with temperature – but it was always assumed that the total surface water of the earth was constant. There is now increasing evidence that the oceans of the planet have almost twice as much water about 3 to 4 billion years ago – enough to submerge the modern continents. It is suspected that rocks in the current mantle, the thick layer beneath the crust, the water’s water or more in their mineral structures sequester. But early in Earth’s history, the mantle, which was warmed by radioactivity, was four times warmer. Working with hydraulic presses has shown that many minerals may not contain as much hydrogen and oxygen during jacket temperatures and pressures. A new model of the evolution of the mantle over time, based on these results, suggests that the mantle could hold much less water in the past. And the most likely home for the water was the surface. This flood could have propelled the engine of plate tectonics and made life more difficult to start on land.