Proceedings of the National Academy of Sciences of the United States of America

About the PNAS Member Editor
Name Valley, John W.
Location University of Wisconsin-Madison
Primary Field Geology
Secondary Field Geophysics
 Election Citation
Valley studied evolution of the Earth over 4,400 million years, revealing the nature and timing of the earliest known crust, habitable oceans and microfossils. ~
 Research Interests
John Valley's earliest research concerned high-grade metamorphism and Precambrian geology with fieldwork in many areas of Asia, Australia, Europe, and N. America. More recently, he has investigated isotope geochemistry of magmas of known age from 4.4 billion years to Recent. His studies of zircons from the Earth's earliest crust have shown that the planet's surface cooled more quickly than previously thought, that hot "Hadean" conditions lasted less than 100 million years after the formation of the Earth and Moon, and that habitable conditions and oceans existed on Earth over 800 million years before the earliest known microfossils. He has also shown that these ancient fossils lived in complex communities of microbial life 3,465 million years ago, indicating that the first life came earlier. His other interests include mineralogy, paleoclimatology, and astrobiology. In 2005, he established the WiscSIMS Laboratory at The University of Wisconsin, which is dedicated to developing procedures for measurement of isotope ratios at nm- to mm-scale in minerals and novel applications of stable isotope geochemistry.

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