Horizon
Series 28 Episode 13
First broadcast April 13th, 1992
From Wikipedia
Donald Canfield is a geologist born in 1958, most famous for his work on ancient ocean chemistry. The Canfield ocean, a sulfidic partially oxic ocean existing between the Archean and Ediacaran periods, takes its name from his seminal paper.
He has been the director of the Nordic Center for Earth Evolution (NordCEE) since August 2006, and works at the University of Southern Denmark. He was awarded the European Geosciences Union's Vladimir Ivanovich Vernadsky Medal in 2010.