COMPARISON OF MIDDLE EOCENE FLORAS FROM THE PACIFIC WEST AND EUROPE: A NEW APPROACH

There is a number of Middle Eocene floras existing in North America. Only few of them have been compared in depth to the classic contemporaneous assemblages of Germany (Messel, Eckfeld, Geiseltal). But, such comparisons obviously have some potential for obtaining important data on paleophytogeographic connections and paleoclimatic regimes. The respective paleofloras from the West Coast have largely been studied only conventionally by gross morphological characters of leaves or are almost unknown. Palynological data are rare, and cuticular studies are still completely missing. The application of palynology and cuticular analysis should now lead to a sound comparison of (Middle) Eocene floras from the Pacific West and Europe. Comparability is especially enhanced by the fact that there is a chance for comparing floras of a similar setting. First well preserved and promising microfloras have now been obtained from Chalk Bluffs (Foothills of the Sierras E of Sacramento, California), and from the Coos Bay area (S-Oregon coast). Surprisingly, results have even been obtained from thermally affected sediments at Tainum Creek, Washington. Preliminary analyses have yielded a number of taxa in common with the European microfloras, but there are also some differences of potential paleoclimatic significance. Some of the typical indicators for a paratropical climate which are characteristic for the European localities are obviously rare (e.g. palms) or absent (Schizaeaceae, Icacinaceae, most Normapolles) from the West Coast localities. The rich macroflora from Chalk Bluffs has proven potential for cuticular studies which will hopefully provide another dataset for comparison. The strata in the Coos Bay area have yielded few macrofossils but need to be collected thoroughly in the future.