Ultima Thule

In ancient times the northernmost region of the habitable world - hence, any distant, unknown or mysterious land.

Sunday, April 23, 2006

Taiwan Moves Closer to Mainland, Pulled by Forces That Molded Its Mountains

By Aussiegirl

Well, it looks like if China and Taiwan can hold off killing each other for about a million years, the world will become a safer place.

Taiwan Moves Closer to Mainland, Pulled by Forces That Molded Its Mountains - New York Times


Politically, Taiwan's relationship to Beijing could be characterized primarily as a rift borne of defiance on one side and menacing rebuke on the other. But geologically, the small island of Taiwan appears to be on a collision course with mainland China. Over millions of years, that is.

Millimeter by millimeter, the same colossal forces that molded Taiwan's steep mountains — and that unleash its earthquakes — are narrowing parts of the Taiwan Strait, bringing the island ever closer to the mainland.

Now an international coalition of scientists from the United States, Taiwan and Japan are planning to delve into those mountain-building processes. And despite friction between Taipei and Beijing, the project's leaders have quietly requested assistance from mainland Chinese geologists. [....]

The survey builds upon a rich history of research exploring Taiwan's topography. Since the 1970's, the island has been a natural laboratory for probing how collisions between tectonic plates, the vast interlocking slabs that make up the earth's crust, gave birth to mountain belts.

"Taiwan is one of the fastest rising mountains in the world," Dr. Wu said. [....]

Taiwan popped up in the Pacific Ocean four million to five million years ago when the Eurasian plate —where mainland China is — slid under an ancient chain of volcanic islands sitting on the neighboring Philippine Sea plate. Sometime later, the two plates somehow reversed roles at the north end of Taiwan: there, the Philippine slab slides under the Eurasian slab.

The Himalayas, an estimated 50 million years old, are also growing rapidly and are of interest to scientists. But Taiwan's smaller scale (roughly the size of Vermont) and greater accessibility make it easier to study, Dr. Wu said. [....]

In fact, the classic theory of how mountains evolve came from research on Taiwan, said Timothy Byrne, a geoscientist at the University of Connecticut and a consultant for the Taiger study. In the early 1980's, John Suppe, a Princeton geologist, and his colleagues calculated that mountains form in subduction zones just as a bulldozer pushes into a pile of sand, creating a wedge-shaped mound in front of its shovel blade.

For Taiwan, the bulldozer blade is the Philippine plate, scraping the top of the Eurasian plate. "That's a pretty good analogy for the top 10 or 15 kilometers of Taiwan," Dr. Byrne said. "It's not grains of sand but small blocks of the earth's crust that are breaking apart." [....]

Meanwhile, as the Philippine and Eurasian plates converge at eight centimeters a year, the island's mountain zone keeps gradually growing on its west side. Some parts of the strait are becoming shallower and narrower, said Dr. Byrne of Connecticut. It's impossible to predict how the plate interactions will change, but if current patterns hold, he said, in a few million years "Taiwan Strait will be gone, will be dry land."

Will the island and the mainland ultimately reunify? Asked the question at a recent scientific meeting in San Francisco, Dr. Lee smiled enigmatically and chuckled. "If the Chinese can be that patient," he said.


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