Hawaii mountains withering away

Last Updated: Sun, Dec 23, 2012 09:50 hrs

Washington, Dec 23 (IANS) In the future, Oahu's Koolau and Waianae mountains in the volcanic island chain of Hawaii may be reduced to a flat, low-lying land. The rocks that comprise these mountains are dissolving from within, say scientists.

"We tried to figure out how fast the island is going away and what the influence of climate is on that rate," says Brigham Young University (BYU) geologist Steve Nelsonm, who led the study. "More material is dissolving from those islands than what is being carried off through erosion."

The research pitted groundwater against stream water to see which removed more mineral material. Nelson and his BYU colleagues spent two months sampling both types of sources, the journal Geochimica et Cosmochimica Acta reports.

Besides ground and surface water estimates from the US, the Geological Survey helped calculate the total quantity of mass that disappeared from the island each year.

"All of the Hawaiian Islands are made of just one kind of rock. The weathering rates are variable, because rainfall is so variable, so it's a great natural laboratory," says Nelson.

Forecasting the island's future also needs to account for plate tectonics.

As Oahu is pushed northwest, the island actually rises in elevation at a slow but steady rate. You've heard of mountain climbing; this is a mountain that climbs, according to a Brigham statement.

According to the researchers' estimates, the net effect is that Oahu will continue to grow for as long as 1.5 million years. Beyond that, the force of groundwater will eventually triumph and the island will begin its descent to a low-lying topography.

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