Tom KroghThomas Edvard Krogh

(1936-2008)

Tom Krogh was an internationally respected scientist who developed advanced techniques in uranium-lead dating of geological processes. Their application by Tom and numerous other researchers have revolutionized our understanding of Earth’s geologic evolution through its 4.5 billion-year history by placing geologic events in precise time sequence. After over three decades, his approach and methods are acknowledged to be unsurpassed and are still used in the best laboratories around the world today.
  
Tom joined the Department of Geology at the University of Toronto in 1975 and established the world-renowned Jack Satterly Geochronology Laboratory at the Royal Ontario Museum (ROM), which officially opened in 1977. He was born and raised in Peterborough, Ontario, and received his M.Sc. in Geology from the Faculty of Engineering at Queen’s University followed by his Ph.D. from the Massachussetts Institute of Technology. He then worked at the Carnegie Institution of Washington as a post-doctoral fellow and continued on as a Staff Scientist for 11 years before joining the ROM as a Curator. He retired from the ROM in 2001, but continued his work as a Professor Emeritus at the University of Toronto.Tom in the lab

His innovative technical developments permitted the acquisition of age data with exceptional levels of precision and accuracy that had previously never been achieved. The driving force behind Tom’s creative scientific achievements was his great passion for understanding complex geological processes. Dating rocks to unravel the history of the Earth's crust by Tom, his coworkers and collaborators, has contributed to the development of an astonishingly detailed understanding of Precambrian shield areas. In particular, he used these techniques to make several important breakthroughs in understanding how the ancient crust in the Superior and Grenville geologic provinces of Ontario formed. His work on zircon crystals from Sudbury provided an age for its mineral deposits and demonstrated shock features that could only have been caused by meteorite impact. Tom identified similar features in zircon grains from the worldwide layer of dust that was laid down by the impact of another giant meteorite at the end of the age of dinosaurs. By dating these crystals, he and his coworkers were able to show that they came from the Chicxulub crater in Mexico, the first unambiguous evidence for the location of this impact.
   Tom with pumkins        

Through Tom’s mentorship, many students and post-doctoral fellows developed the expertise to establish their own successful laboratories. Two of Tom`s seminal papers have been cited ~2900 times (total career citations: ~6205 so far), which is rarely achieved in geology. He was named a Fellow of the Royal Society of Canada, and received the Logan Medal, which is the Geological Association of Canada’s highest award, the J. Tuzo Wilson Medal of the Canadian Geophysical Union, the Past President’s Medal of the Mineralogical Association of Canada, and an Honorary Doctor of Science from Queen's University. He was also named Fellow of the American Geophysical Union and was an elected Member of the Norwegian Academy of Science and Letters.
           
Tom will be long remembered by his many friends and colleagues around the world for his contributions as a scientist, his great passion for geology and his generosity as a human being.  

Sandra Kamo
Dec. 17, 2008