Dissertation Research: Paleovegetational Response to Volcanism: Eocene/Oligocene Lower Cedarville Flora, California

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9520826 Fisher At numerous sites in northern California, Oregon, and Washington, volcanic deposits preserve ancient vegetational types and make possible the critical analysis of trends in plant species replacement and habitat change through time. Graduate student Jeffrey Myers under the guidance of Professor Richard Fisher at the University of California-Santa Barbara is studying deposits of Eocene and Oligocene age, ca. 30 million years old, in the West, to assess vegetational changes across a broad region of the landscape over a relatively short span of geological time. The goal is to distinguish between a single, major secular shift in vegetation (moist humid tropical to seasonal temperate forest) or a more complex mosaic pattern of local habitat types. Numerous deposits of the same age will be visited and sampled, and their major plant components identified; a critical aspect of the research is to incorporate modern analyses on post-depositional processes (so-called taphonomic processes like decay and local transport by water or by animals) so ensure that fossil deposits accurately reflect local vegetation. Interest in global climate change and its environmental effects reinforces the need for fine-scale analysis of the fossil record. The Eocene-Oligocene focus of the proposed research emphasizes a time of global cooling, with resulting shifts in temperate-zone vegetation. How and over what timescales the vegetation changes in species composition are major unresolved questions in paleontology, to which this research brings a rigorous taphonomic approach.