Clark M. Johnson » Emeritus Faculty Clark M. Johnson Vilas Distinguished Professor, Emeritus Isotope Geochemistry, Geochronology, Petrology, Astrobiology Office 329 Weeks Hall work Phone: 608-262-1710work Email: clarkj@geology.wisc.eduINTERNET Website: http://geoscience.wisc.edu/johnson Categories: Emeritus Updated 5 months ago.