Fossil Wood from the Middle Miocene Conejo Volcanics, Santa Monica Mountains, California

Abstract

Evidence that the upper Conejo Volcanics erupted subaerially is con- <br /><br />firmed by the discovery of fossil wood preserved in a —13.5 Ma tuff breccia <br /><br />exposed on the northern flank of the Santa Monica Mountains, California. This <br /><br />middle Miocene wood represents a low montane geoflora of hardwoods and co- <br /><br />nifers that lived at elevations greater than 1,300 m. Ponderosa Pine, Douglas Fir, <br /><br />Incense Cedar, and specimens from the dicotyledonous families Fagaceae (ever- <br /><br />green and live oaks), Rosaceae (mountain mahogany), and Rhamnaceae (mountain <br /><br />lilac) have been identified by thin section analysis. Preservation of this wood <br /><br />varies from amorphous clayey limb casts to splintered surfaces and detailed cell <br /><br />features. This is the first record of fossil trees in a tuff breccia from the Los <br /><br />Angeles basin region.