By Dan Vergano, USA TODAY

Updated 15h 30m ago
s
Don't lay out any welcome mats — wait about 100 million years or so — but eventually Asia and the Americas will smash together, geologists report, burying both the Arctic Ocean andCaribbean Sea.
  • This undated photo shows Grand Anse beach in the foreground and the Caribbean island of Grenada in the distance. Geologists report, that in time, both the Arctic Ocean and Caribbean Sea will be buried because of merging continents.
    By Robert Mazziotta, AP
    This undated photo shows Grand Anse beach in the foreground and the Caribbean island of Grenada in the distance. Geologists report, that in time, both the Arctic Ocean and Caribbean Sea will be buried because of merging continents.
Enlarge
By Robert Mazziotta, AP
This undated photo shows Grand Anse beach in the foreground and the Caribbean island of Grenada in the distance. Geologists report, that in time, both the Arctic Ocean and Caribbean Sea will be buried because of merging continents.
The future supercontinent, "Amasia," described in the journal Nature on Wednesday, will encompass Asia, Africa and the Americas. Driven by continental drift, the assemblies of such "supercontinents," such as Pangea some 300 million years ago, have reoccurred throughout Earth's history.
"We are due for a supercontinent to form within about the next 50 to 200 million years," says study lead author Ross Mitchell of Yale University. "In theory, we think this supercontinent will cover half a hemisphere of the Earth."
Asia already rests on continental crusts from India, Siberia and Europe, but the coming confluence of continents would create an unbroken landmass unrivaled in size since the dawn of the age of the dinosaurs. "Antarctica just ends up hanging out there by itself," Mitchell says.
Like titanic jigsaw puzzle pieces, three such supercontinents including Pangea, which encompassed all the continents, have formed and broken apart on Earth in the last 1.8 billion years.
Some theories that tried to forecast how continents would shift over time had seen supercontinents breaking apart, but eventually reforming on the same spot over today's Atlantic Ocean. Others pictured them bouncing back and forth between opposite sides of the planet.
The Yale team instead looked at recent magnetic rock records to suggest that supercontinents form midway between those extremes. In the team's explanation, individual continents slide together sideways along their volcano-rimmed margins.
"It makes sense geodynamically — continents being pulled like rafts to assemble," says geologist Bernhard Steinberger of the GFZ German Research Centre for Geosciences, by e-mail. He cautioned that geologists need to nail down definitively the past location of the continents to prove any of the supercontinent theories, including the latest one.
Essentially, the Yale team suggests that ocean floors, which dive beneath continents to trigger earthquakes and volcanoes, grease the skids for supercontinents. Once assembled, an upwelling of heat from below sends the supercontinent drifting apart again, a cycle that repeats itself every few hundred million years.
"This is big ticket stuff, the history and the fate of the continents, the driver of the climate and the ultimate source of geologic resources," says geologist Brendan Murphy of Canada's St. Francis Xavier University, who was not part of the study. "Whether they are right or wrong, we will test (the idea) and learn a lot about the past and future of the planet," he says.
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Posted 19h 47m ago | Updated 15h 30m ago
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  • Tony Adams
    Where is the graphic? Lazy journalists...