Researchers discovered that the mountains found on Oahu (Koolau and Waianae), Hawaii's third largest island, are being eroded from within by groundwater. Thus, they are quite likely to shrink as the years go by, and ultimately turn into plains.
However, erosion isn't the biggest culprit. Instead, scientists say, the mountains of Oahu are actually dissolving from within.
"We tried to figure out how fast the island is going away and what the influence of climate is on that rate," said Brigham Young University geologist Steve Nelson.
"More material is dissolving from those islands than what is being carried off through erosion," he said.
The research pitted groundwater against stream water to see which removed more mineral material. Nelson and colleagues spent two months sampling both types of sources.
Estimates from the US Geological Survey helped them 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, too, because rainfall is so variable, so it's a great natural laboratory," Nelson said in a University statement.
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, researchers said.
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.
