Geologists Suggest Meteorite Caused Unusual Rock Formation

Marjorie A. Chan of the University of Utah and Walter Alvarez of the University of California-Berkeley believe some of the unusual rock formations in the park may have been caused by a meteor striking the Earth about 20 miles away at a site called Upheaval Dome.

The unusual deformations in the layers of rock referred to as the Carmel Formation and the Entrada Sandstone in and around the national park have long been a subject of debate among geologists. Five theories on the origin of this crinkling ó ranging from an earthquake to minerals evaporating within the rock ó have been put forth, but Chan and Alvarez say none of these explanations fully accounts for the features found there.

The two researchers, joined by Berkeley colleagues Erick Staley and Diane O'Connor, suggest that the deformation may be an example of folding and liquefaction due to impact shaking. They believe the possible source of that impact shaking may have been a meteor at Upheaval Dome, which has a concentric structure similar to a crater. The dome has long been considered the remnant of a salt diapir, although more recently scientists have speculated that it could have been an impact crater.

The two geologists actually came up with the impact shaking concept independent of one another ó Alvarez while passing through the area and Chan while conducting sabbatical research there. When they learned of each others' similar hypotheses, the two decided to collaborate on a scientific paper. Their hypothesis was published in the July 1998 issue of the scientific journal Geology.

Chan says the deformation of rock in the area points to an energy release equivalent to at least a magnitude 8 earthquake.

"It's a controversial idea and still needs to be tested with more data," Chan says. "But it's a novel concept and can explain some of the rock wrinkles better than any of the previous ideas that have been published."

Chan says their paper is a starting point from which to examine the area more closely in an attempt to explain the unusual deformation and prove or disprove the impact theory.