Craig A Johnson, Ph.D.

Craig attended Dartmouth (AB), Michigan (MS), and Yale (PhD). He held a NASA postdoc and a staff position at the American Museum of Natural History in New York prior to joining the USGS in 1992. Craig is responsible for a stable isotope laboratory in which isotopes of carbon, hydrogen, nitrogen, oxygen, and sulfur are measured in rocks, waters, gases, and biological materials. Craig studies ore genesis, environmental impacts of mining, the source and fate of solutes in natural waters and crustal fluids, the isotopic record of marine sulfate, and isotopic records of paleoenvironments.