Los Angeles Times
: Every year about 60 tons of helium gas escapes into the atmosphere from steam vents and hot springs in Yellowstone National Park. The helium, which has been accumulating underground over hundreds of millions of years, only started seeping out over the past 2 million years. On a geologic time scale, that seepage is considered a recent phenomenon, according to William Evans of the US Geological Survey, coauthor of a recent study
published in Nature
. While helium is constantly being produced in Earth’s crust as uranium and thorium decay, it usually escapes via groundwater or as the result of tectonic activity. At Yellowstone, however, the helium has collected over time in the 2.5-billion-year-old rock unique to the area. Volcanic activity that began some 2 million years ago probably triggered the helium release, and that activity is still evident in the area’s numerous geysers, hot springs, and fumaroles. Although there is currently a helium shortage for use in industry and electronics, it wouldn’t be economical to try to capture and purify the helium in Yellowstone, says Evans.