Geologists Study How Beachfront Property Turned Mountainous

HOUSTON, Sept. 2, 1999 -- A modern cowboy would feel right at home along the Rocky Mountains in southern Wyoming, but if he could have been there 2 billion years ago, he would have needed a swimsuit--he'd be on the beach.

A team of scientists is studying how North America formed almost 2 billion years ago along the Rocky Mountain range from Laramie, Wyo., to Albuquerque, N.M.

Geologists are mapping the earth beneath North America to try to understand how ancient pieces of land collided with what is now Canada and Wyoming, which scientists believe was once a coastline, to form our continent.

They are particularly interested in the transition boundaries between the ancient land masses, formed as island arcs collided with the proto-North American continent between 1 and 2 billion years ago to make southwestern North America, says Alan Levander, a Rice University geophysicist, one of the principal investigators of the project.

They will look for clues as to why mountains popped up in certain areas and how the modern Rockies formed, telling information about how the land masses came together. The ancient sutures along which the continent was constructed appear to provide strong control over more modern deformations that produced the relatively young Rocky Mountains.

A team of 19 researchers from 13 American universities and Germany, led by Karl Karlstrom of the University of New Mexico, are undertaking the project together. Funded with a $2.7 million grant from the National Science Foundation, the active source seismology experiments for the "Continental Dynamics of the Rocky Mountains" project began in late July and run through October.

The team's research techniques provide the equivalent of an ultrasound image of what lies beneath the American Rockies, allowing them to look at the different types of old rock layers--the boundaries created as pieces of Earth's crust were added to North America. Along the Rocky Mountains from Wyoming to New Mexico, sensitive seismic equipment records manmade shaking of the Earth, created by controlled explosions, buried deep within the Earth, and large vibrating trucks, frequently used in oil exploration, which inject 250,000 pounds of force into the Earth. The measurements will reveal the density of the rocks and material that the seismic waves pass through, allowing researchers to visualize the structure of what lies far under the Earth's surface, about 25 miles down, where the Earth's crust meets the mantle.

"In doing this we hope to image the ancient suture zones along which the continent was constructed, and which are now controlling active tectonics," Levander says.

Geological and earthquake seismology studies began over a year ago, and will continue into next year.

The Continental Dynamics of the Rocky Mountains project is a three-year, multi-institutional project funded by the Continental Dynamics Program of the National Science Foundation.