New Evidence for a Pliocene Marine Embayment along the Lower Colorado River Area, California and Arizona

摘要: Marine foraminiferal, marine to fresh-water molluscan, and brackish- ostracode faunas occur in a thick section of limestone, silt, clay the Bouse Formation along Colorado River from Parker Yuma an area now isolated sea. Faunas Parker-Blythe-Cibola are limited number species but remarkably persistent through formation. The presence Foraminifera, including Globigerina sp., is considered evidence that was continuously connected with ocean. Several thousand feet similar sediments found subsurface near contain which at shallow depths those north, greater bathyal assemblages abundance globigerinids, indicate post-Miocene age for section, oceanic conditions. It likely this embayment extended into Imperial Valley, where probable Pliocene also contains faunas. Evidence presented here strongly indicates large long-lasting lower River, Valley.