REVISITING THE MIOCENE WOOD FLORA FROM VANTAGE, WASHINGTON

Thousands of fossilized logs of Middle Miocene age are entombed in the Columbia River Basalts of central Washington state. Professor George Beck of Central Washington University undertook a comprehensive study of the wood beginning in the 1930's. He published a series of informal papers on the deposits in the mid 20th century, but did not provide any formal species diagnoses. In the 1960's Prakash and Barghoorn published three papers providing formal descriptions for a number of species from Beck's main collecting horizon at Vantage. Since then, other authors have reviewed specific taxa from Vantage but there has been no comprehensive review of the deposit. The purpose of this study is to provide a comprehensive overview of the Vantage woods, to use modern wood anatomical resources to evaluate prior descriptions and make corrections where warranted, to describe and illustrate new taxa that have not previously been published, and where possible, to understand the biogeographic relationships of the fossil species with their modern relatives. This study also compares the Vantage wood flora with coeval pollen and plant megafossil deposits of the region. Preliminary results show that the Vantage flora consisted of a diverse mix of temperate tree types, representing at least six gymnosperm and eighteen angiosperm genera. Many of these are no longer present in the native forests of the northwestern United States, but modern relatives persist in eastern Asia and the eastern United States. The genera present at Vantage show a high degree of overlap with similarly aged megafossil and pollen floras from Washington, Oregon and Idaho.