The first billion years on Earth and Mars: A geologist’s perspective – Clark M. Johnson
Despite the likelihood of early habitability on both Earth and Mars, the geologic evolution of these two planets, and the rock record they preserve, is quite different. Plate tectonics on Earth played a central role in evolution of our biosphere, and yet has destroyed much of the early Earth rock record, creating great challenges for finding evidence for early life on Earth. Mars did not have Earth-style plate tectonics, but the evidence is clear that Mars was habitable very early in its history. Preservation of the early Mars geologic record is excellent, raising the possibility that it might contain evidence for the earliest life in the Solar System. Of course, geologic field work on Mars is a bit more difficult than on Earth. This talk will explore the geologic evolution of these two planets in their first billion years or so, highlighting evidence for habitability and life.
About the Speaker:
Clark M. Johnson Johnson is the Vilas Distinguished Professor of geoscience at the UW Madison. His specialties are Isotope Geochemistry, Astrobiology, Geochronology, & Petrology. His primary research interests lie in application of stable and radiogenic isotopes to study of ancient life and crust and mantle evolution. This includes topics ranging from astrobiology to the origin of igneous rocks and evolution of volcanic systems. He is also interested in mountain building and metamorphism, as well as low-temperature studies involving diageneis, sedimentary provenance, migration of ancient people, and geomicrobiology. He is the principle investigator for the Wisconsin Astrobiology Research Consortium.