The eastern San Francisco Bay region (Contra Costa and Alameda Counties, California) is a geologically complex area divided by faults into a suite of tectonic blocks. Each block contains a unique stratigraphic sequence of Tertiary sediments that in most b
McDougall, Kristin,Block, Debra dblock@usgs.gov. Digital database of microfossil localities in Alameda and Contra Costa Counties, California. 2014-01-01.