1. Senior oceanographer at the National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560.
2. Research geologist in the Ocean Chemistry and Geology Department of the Atlantic Oceanic and Meteorological Laboratory, National Oceanic and Atmospheric Administration, Miami, Florida 33149.
3. Directs the Radiocarbon Laboratory at the Environmental Research Center, Smithsonian Institution, Rockville, Maryland 20852.