2009 Portland GSA Annual Meeting (18-21 October 2009)

Paper No. 1
Presentation Time: 8:00 AM

THE ROLE OF THE OCEANS AND THE SUN IN LATE PLEISTOCENE AND HISTORIC GLACIAL AND CLIMATIC FLUCTUATIONS


EASTERBROOK, Don J., Dept. of Geology, Western Washington Univ, High St, Bellingham, WA 98225, don.easterbrook@wwu.edu

Lidar imagery of the southern part of the Fraser Lowland in WA reveals previously unknown, multiple, latest Pleistocene (Sumas Stade) end moraines overlying Everson glaciomarine drift (gmd). Multiple marine shorelines extend from about 540’ to about 100’above present sea level and are truncated by two of the oldest Sumas end moraines. These moraines are younger than the underlying Everson gmd, which is well dated at 11,700 14C yrs. B.P., and older than 11,400 14C yrs. B.P. basal bog dates behind the moraines. Recession of the ice from the outermost moraines was followed by building of at least nine end moraines, some of which clearly represent glacial readvances. Basal bog dates from a kettle in outwash from the youngest Sumas moraine has been dated at 10,250 14C yrs. B.P.

Isotope data from Greenland ice cores and historic atmospheric and oceanic temperature records show a consistent pattern of fluctuating 25-30–year warm and cool periods over the past 500 years. During the past century, five of these climate fluctuations can be tied to glacial oscillations, oceanic temperature changes, atmospheric temperature changes, and solar variation.

The question is—what drives these oscillations? The older fluctuations can be linked to changes in 14C and 10Be isotope production rates in the upper atmosphere, suggesting variation in cosmogenic radiation. Historic climatic and oceanic temperature fluctuations are associated with solar variations. The excellent correlation of glacial, climatic, oceanic, and solar variation strongly suggests cause and effect relationships. Past patterns of these variations allow projection into the future.