Printer Friendly

What's holding up the high Sierras?

What's holding up the High Sierras?

Since the 1920s, geologists have believed that the high peaks of the Sierra Nevada rest atop a thick root of buoyant crustal rock that supports the fabled California range. But seismologists who have analyzed earthquake waves passing beneath this region now say they can't find the crustal root.

Craig H. Jones and Hiroo Kanamori of the California Institute of Technology in Pasadena and S.W. Roecker of Rensselaer Polytechnic Institute in Troy, N.Y., examined seismic waves recorded by receivers in and around the Sierra region during a recent experiment. The speed of the waves passing beneath the mountains indicates that the crust has a thickness of only 25 to 35 km under the high peaks of the southern Sierras, which stretch from Sequoia National Park to Mono Lake. Previously, workers had put the depth of the crust in this region at 50 km.

Gravity studies of the region indicate that some low density rock must underlie the Sierras. One possible candidate, Jones suggests, might be a zone of hot, buoyant rock in the mantle, helping to support the peaks. But seismic experiments so far have failed to find this hot mantle region.
COPYRIGHT 1990 Science Service, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1990, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:underlying rock
Author:Monastersky, Richard
Publication:Science News
Date:Dec 15, 1990
Words:199
Previous Article:Larger grave for the Himalaya.
Next Article:The New Madrid quack.
Topics:


Related Articles
Nevada's Basin and Range: down on its luck.
WILL THIS BE WINTER OF OUR LEARN-TO-TENT? WILDERNESS COURSE OFFERED.
BRIEFLY : OFF-DUTY OFFICER TEST SHOWS ALCOHOL LEVEL.
AGUA DULCE TRAIL GETS $1.5 MILLION; THREE-MILE SECTION TO BE MOVED FOR HIKER SAFETY.
SIERRA NEVADA RANGE ON THE MOVE, REPORT SAYS.
CHAOS, UNCERTAINTY, DANGER CHALLENGING THE RAPIDS A REAL THRILL RIDE.
FOLIAGE FLAIR EASTERN SIERRA OFFERS PLENTY OF EAST COAST CHARM IN FALL.
STREET FAIR 'GROWS UP'.
AQUEDUCT PIPELINE GETTING BEEFED UP.
SPARKS ON A SIZZLING-HOT DAY RAPID SERIES OF SMALL BRUSH BLAZES KEEPS FIRE CREWS BUSY.

Terms of use | Copyright © 2016 Farlex, Inc. | Feedback | For webmasters