H.D. Holland622551hollandeditor.jpg My research is focused on two problems: the long-term evolution of the atmosphere and the long-term evolution of seawater. Emphasis in the first problem area is on the Great Oxidation Event between ca. 2.3 and 2.0 Ga, in partcular the change from an atmosphere that probably contained a significant amount of methane to one that contained a significant amount of oxygen. During the next few years we hope to define the cause of this change and to refine its timing. The past several years have shown that the composition of seawater changed very significantly during the course of the Phanerozoic. However, the actual course of the chemistry of seawater is still poorly defined. The causes are clearly related to tectonism, marine biology, and the flooding of the continents, but a coherent theory relating these processes to the history of seawater remains to be constructed. We hope to contribute materially to this enterprise. E-mail: holland@eps.harvard.edu Read More Read Less