How the Rockies may have been ‘formed by giant suction’

The presence of a two-mile-thick layer of marine shale in Wyoming supports the theory.

Washington: A new study shows that the Rockies may have been formed when a giant suction created a counter force that thrust the mountains upward.

Mountains generally form where continental plates crash into each other but the nearest plate boundary to the Rockies runs along the west coast of North America, forming the coastal mountain ranges.

"The Rocky Mountains have always been a problem because they look like a collisional mountain range. They look like the Himalayas but we can`t find the India," Discovery News quoted Basil Tikoff of the University of Wisconsin, Madison, as saying.

"It`s just a weird situation in the Rocky Mountains that despite the fact that they have extraordinarily good geology and geophysics that we don`t get the basic geology of how they formed."

The new hypothesis revolves around the idea that underneath Wyoming is an area where the North American plate is extra thick, protruding like a hull into the more fluid part of the upper mantle below.

As the Farrallon plate slid underneath, the fluid layer beneath flowed around the hull shape and into the cavity where the plates meet and as it tried to flow out again, it created a downward suction force.

The suction, combined with the plate pressing in from the side, created the forces that pushed up the Rockies, said study lead author Craig Jones of the University of Colorado at Boulder.

The presence of a two-mile-thick layer of marine shale in Wyoming supports the theory.

"I suspect for people who are thinking hard about this problem, this is likely to become a leading candidate if not the leading candidate" said Tikoff.

"It makes predictions you can test."

The new work appears in Geosphere.


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