1 U.S. Geological Survey, 345 Middlefield Road, M/S 977, Menlo Park, CA
This report is preliminary and has not been reviewed for conformity with USGS
editorial standards (or with the North American Stratigraphic Code). Opinions
and conclusions expressed herein do not necessarily represent those of the
USGS. Any use of trade, product, or firm names is for descriptive purposes
only and does not imply endorsement by the U.S. Government.