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John Valley

John Valley

Expert on geology and geochemistry of the Earth.

Professor of Geoscience College of Letters and Science Work: 608-263-5659 — Home and cell phones available upon request Home page


  • Expert on geological conditions of the early Earth: the formation of oceans, growth of continents, and surface conditions hosting the first life on Earth.
  • Expert on stable isotope geochemistry as applied to genesis of rocks and minerals, astrobiology, paleoclimatology, and meteorites.


  • Founded WiscSIMS, the Wisconsin Secondary Ion Mass Spectrometer Lab at UW-Madison for in situ microanalysis of stable isotope ratios.
  • Fellow: AAAS, American Geophysical Union, Geochemical Society, European Association of Geochemistry, Geological Society of America, and Mineralogical Society of America. Past-president: Mineralogical Society America.
  • Discovered the oldest samples of Earth, 4,400 million year old zircons, showing that oceans and clement conditions existed on the surface of earliest Earth.