Robert Gaines, professor of geology at Pomona College, will be the featured speaker at a Department of Geoscience seminar. His talk is titled, The Great Unconformity, Seawater Chemistry, and the Cambrian Explosion.

His research focuses on microbial-mineral interactions as a link between the geosphere and the biosphere. Gaines works on ancient sedimentary rocks in South China, British Columbia, and the American Great Basin.