Rhonda Zurn, College of Science and Engineering,, (612) 626-7959

Preston Smith, University News Service,, (612) 625-0552

R. Lawrence Edwards is University of Minnesota’s first to receive the award

MINNEAPOLIS / ST. PAUL (02/09/2011) —The U.S. National Academy of Sciences has selected University of Minnesota professor R. Lawrence Edwards to receive the prestigious Arthur L. Day Prize and Lectureship honoring his scientific contributions to the study of the physics of the Earth. Edwards, a geology and geophysics professor in the University’s College of Science and Engineering, is only the 14th recipient of the Day Prize since its inception in 1972 and the first from the University of Minnesota.

Edwards is best known for his development of extremely precise methods for measuring the ages of rocks. To date the rocks, he uses the "uranium-thorium" (also called the "thorium-230") dating method, in which he must detect incredibly small amounts of the elements uranium and thorium. He uses these methods to date rocks found in caves in China to document climate change patterns in history. By also measuring the proportions of different forms of oxygen, he can tell how much rain fell at the time the rock was deposited.

Edwards and a colleague used those techniques to trace variations in the strength of monsoon rainfall in China and linked weak monsoons to the fall of several historical dynasties. They have tracked the monsoons with great accuracy back 400,000 years, when Homo erectus, not Homo sapiens, inhabited the region.

"The monsoon history is an exciting piece of work coming out of Minnesota," Edwards said. "It’s the best-dated climate record covering this time period. We pieced it together from many stalagmites of varying ages."

In another example, about 11,500 years ago an abrupt, worldwide climate change sent the average temperature in Greenland soaring by a whopping 16 degrees C in the space of a decade. Edwards and his colleagues detected the "signature" of this warming in Chinese cave stalagmites, where it appeared as a strengthening of the monsoons during that period. Labs around the world have adopted Edwards’s work with cave rocks to study climate and to plot the course of climate change in time.

In more recent research, Edwards and his colleagues published research on a rock found in 2007 in a Chinese cave that contained what was determined to be a 100,000-year-old jawbone. In dating the rock with the jawbone, Edwards and his colleagues raised profound questions of whether modern humans could have made it across the vast expanse of Asia far earlier than suspected. Because the remains also bore characteristics of more primitive humans who were already in the area, it is possible that the two groups could have coexisted for some time the way moderns and Neanderthals did in Europe.

“It’s amazing to me what you can find in the natural world if you know how to look,” Edwards said.

Edwards will be honored for his research and receive the $20,000 Day Prize at a ceremony on Sunday, May 1, during the National Academy of Sciences’ 148th annual meeting.