|Statement||By Chester A. Arnold.|
|Series||Contributions from the Museum of Paleontology. University of Michigan,, v. V, no. 8|
|LC Classifications||QE701 .M5 vol. 5, no. 8, etc.|
|The Physical Object|
|LC Control Number||37028259|
Get this from a library! Observations on the fossil flora of eastern and southeastern Oregon.. [Chester A Arnold]. Download PDF: Sorry, we are unable to provide the full text but you may find it at the following location(s): (external link)Author: Chester A. Arnold. With new chapters on additional flowering plant families, paleoecology and the structure of ancient plant communities, fossil plants as proxy records for paleoclimate, new methodologies used in. mon bivalve fossil species on Oregon’s coast and a brief description of each: Anadara devincta—Oregon’s most common marine fossil, similar in ap-pearance and shape to the cockles of today (see photo at right). Anadara devincta is an indicator fossil world-wide for Miocene-age formations. Fossils You Can Find on Oregon Beaches Continued.
During the time that the Eocene and Oligocene fossil beds were being deposited, most of northwestern Oregon lay beneath a warm shallow sea whose southeastern shorel ine ran approximately through the Eugene area (Lowry, ). Marine invertebrate animals lived in great numbers on the sea floor, while semitropical forests grew along the coast. Fossil remains ot vertebrates, mollusks, and leaves in both formations show that the sediments are continental lake and stream deposits. These sediments are widely distributed over the plains area ot the Snake River from the general vicinity of Hagerman, Idaho, to Huntington, Oregon. Plant taxa from these fossil sites are characteristic of the modern eastern North American deciduous forest zone, principally the mixed mesophytic forest, but also include extinct taxa, taxa known. However, until now, no reliable fossil records of Mahonia had been identified from East Asia, even though the genus is widely distributed and highly diversified in the modern East Asian flora.
Oregon’s High Desert is a place apart, an inescapable reality of physical geography. The region forms an extensive area that is substantially different in climate, elevation, and hydrology from any other part of Oregon, and it has a distinctive human history. Fossil plants and soils indicate mean annual temperature of (–) °C and mean annual precipitation of (–) mm. Miocene paleoclimatic changes in eastern Oregon show no. The lower portion of this section is composed mainly of shale which, from its resemblance to the Knoxville so usually developed in California and south-central Oregon, is assumed to be of this age. The Chico is exposed at Mitchell and Spanish Gulch. Only a single fossil has thus far . These global trends also were felt in eastern Oregon, where fossil leaves indicate marked cooling and drying between about 16 and 15 Ma (Wolfe et al., ; Graham, ), and a second cooling and drying to a modern flora by latest Miocene (7 Ma; Chaney, ). Paleosols of eastern Oregon show similar changes between middle Miocene mesic.