Huge magma blobs can spread ripples across the earth's surface, a new study suggests.
Hot blobs of magma — the searing liquid rock beneath the Earth's crust — can spread slow-moving ripples that soar hundreds of meters high across the Earth's surface, a new study suggests.
This phenomenon, which works on geologic time scales, may explain relatively rapid pre-historical changes in sea level that occurred without the typical waxing and waning of the polar ice sheets, which hold and release water on scales of thousands and millions of years. This unexplained sea level rise is one of geology's oldest mysteries.
During the Paleogene era (65 million to 23 million years ago), the land under Scotland moved up and down like a geological yo-yo. The surface rippled up to 1,640 feet (500 meters) over the course of only a million years — a relatively short time span, geologically-speaking.
"It appears to be caused by something deep within the Earth, moving sideways — almost like rats running underneath a carpet," said study author Bryan Lovell of the University of Cambridge.
The sideways movement is actually caused by what's known as convection currents in the mantle. These currents are created when the cooler, denser material in the mantle sinks and the warmer, less dense material rises.
"The hot blob would have spread out from the center of the hot spot rather like a doughnut," Lovell said.