Samuel Epstein (December 9, 1919 – September 17, 2001) was a Canadian-American geochemist who developed methods for reconstructing geologic temperature records using stable isotope geochemistry.
Sam Epstein was born in Kobryn, Belarus, then part of Poland, and as a child his family emigrated to Winnipeg, Manitoba.
In 1947, Epstein moved to the United States to begin a research fellowship with Harold Urey's group at the University of Chicago.
Epstein joined the faculty of the California Institute of Technology in 1952, and continued to explore the new field of stable isotope geochemistry.
He and his students used mass spectrometry to study natural variations in the isotopic abundances of hydrogen, carbon, oxygen and silicon, with applications to archeology, biochemistry, climatology, and geology.