Soil erosion is often considered to be the primary cause of land and mountain loss on islands, but new research has found that on Oahu the mountains are being dissolved and destroyed by groundwater. 
 
 Eventually the mountains Koolau and Waianae on Oahu will be dissolved until the island becomes a nearly flat, very low-lying island similar to Midway. 
 
 “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.” 
 
 
 
 
 
 The research was done by comparing the effects of groundwater compared to stream water, to find out which one was removing more mineral material. “Nelson and his BYU colleagues spent two months sampling both types of sources. In addition, ground and surface water estimates from the U.S. 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,” Nelson said. “The weathering rates are variable, too, because rainfall is so variable, so it’s a great natural laboratory.” 
 
 In order to get an idea of what will happen to the island in the future it was also necessary to take into account plate tectonics. As Oahu is being forced northwest, it actually rises in elevation slowly. 
 
 “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.” 
 
 The researchers got something of a surprise when they were doing their mineralogical analysis of the soil samples that they took. 
 
 “The main thing that surprised me on the way was the appearance of a large amount of quartz in a saprolite taken from a 1-meter depth,” Brian Selck, co-author of the study, said. 
 
 The research was just published in the journal Geochimica et Cosmochimica Acta. 
 
 Source: Brigham Young University 
 
 Image Credits: Brigham Young University ||||| PROVO, Utah, Dec. 21 (UPI) -- The mountains on Oahu in the Hawaiian Islands are dissolving from within under the slow but inexorable onslaught of groundwater, researchers say. 
 
 Sometime in the distant future the mountainous tropical island will be reduced to a flat, low-lying island similar to Midway, scientists at Brigham Young University reported Friday. 
 
 While external erosion is the primary force that wears down mountains, that's not the case on Oahu, they said. 
 
 "We tried to figure out how fast the island is going away and what the influence of climate is on that rate," BYU geologist Steve Nelson said. "More material is dissolving from those islands than what is being carried off through erosion." 
 
 That was the result from comparing groundwater against stream water to see which removed more of the total quantity of mineral material mass that disappeared from the island each year, the researchers said. 
 
 "All of the Hawaiian Islands are made of just one kind of rock," Nelson said, referring to the volcanic composition of the islands. "The weathering rates are variable, too, because rainfall is so variable, so it's a great natural laboratory." 
 
 While Oahu is at present still growing, after about 1.5 million years the force of groundwater will eventually triumph and the island will begin its descent to a low-lying topography, the researchers said.
– Hawaii's island of Oahu is renowned for its mountainous vistas, but someday it's going to be flat as a pancake, or at least as flat as Midway. So say researchers from Brigham Young University in a new study, reports UPI. The big factor isn't what you might expect, namely external erosion. Rather, the island's own groundwater is slowly dissolving the mountains. The weird part, explains PlanetSave, is that Oahu's elevation is actually going to keep growing for 1.5 million years because of how it's being shifted by tectonic plates. But after that, the slow descent begins.