Snapshots From the Meeting

摘要

Whoa there! Geodesists have found that the Sierra Nevada mountains of east-central California are rising so fast that they could have achieved their 3-kilometer height in just the past 3 million years, not the past 30 million years, as suggested by some geologists. William Hammond of the Nevada Bureau of Mines and Geology in Reno and his colleagues reported that GPS measurements combined with satellite radar observations of vertical ground motions show the central and southern Sierras are rising at about 1 millimeter per year. "If that number stands, it would be a rip-roaring uplift rate," says geologist Craig Jones of the University of Colorado, Boulder. Hammond says the high rate across so much of the Sierras argues that they aren't bouncing upward after a heavy piece of the continental plate beneath them peeled off and fell into the mantle. Instead, some aspect of the West Coast's helter-skelter plate tectonics must be responsible.