COMPARING BIOGEOGRAPHIC INFORMATION FROM THE UPPER CRETACEOUS NANAIMO GROUP, AND THE SEPARATE EAST, AND WEST BASINS CURRENTLY COMBINED AS THE UPPER CRETACEOUS GREAT VALLEY SEQUENCE OF THE SACRAMENTO VALLEY

There has long been known similarity between the molluscan faunas of the Nanaimo Group (Vancouver Island region) with those from the northern parts of the Great Valley of California (the Sacramento Valley). To date it has been assumed that the Eastern and Western sides of the Upper Cretaceous strata of the Sacramento Valley have the same fauna, and there is little if any difference of that singular fauna with bio-chronologically important fossils from Nanaimo Group. Here I report on faunal as well as paleotemperature differences between all three of these named regions, supporting preliminary paleomagnetic evidence that the East and West sides of the Sacramento Valley strata of the Great Valley Sequence (or Group). The implications of these findings, if confirmed by more advanced paleomagnetic study, would require a fundamental reassessment of the structural units of the Cordilleran of current day British Columbia, Washington, Oregon and California.