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

Late Pliocene to Holocene Benthic Foraminifers of the Guaymas Basin, Gulf of California, Sites 477 through 481

“…Recent sediment samples from the Gulf of California were included in the taxonomic studies of Cushman and McCulloch (1939, 1948 and McCulloch (1977). Natland (1950), Smith (1970), and Ingle (1973cIngle ( , 1974 reported on upper Miocene-to-Pleistocene foraminifers from land sections of islands in the Gulf of California and from land sections and wells in the northern extension of the Gulf. Moore (1973) studied the Miocene-to-Pleistocene foraminifers of some dredged rocks from the continental slope in the Gulf.…”

Geologic map of the Topock 7.5’ quadrangle, Arizona and California

“…The Bouse Formation contains casts of vegetation fragments; ostracodes (Cyprideis) and reworked Cretaceous coccoliths were reported from an outcrop of the formation 2 km west of the Topock quadrangle (Smith, 1970;Winterer, 1975, Howard and Malmon, 2007). The lower claystone and sandstone subunit of the facies of Santa Fe Railway (Trbfl) at the north edge of the quadrangle yielded remains of fish, pond turtle, rodent, and lizard, as well as bivalves and water reeds (R.E.…”

Biostratigraphy

“…Assuming a constant envelope of maximum and minimum rates of diatom productivity (tuned to climatic extremes) in this region during the early Miocene through Pleistocene interval suggests that a major tectonic and/or sedimentologic event must have occured simultaneously over a wide area at about the Miocene-Pliocene boundary, diluting the steady-state rain of biogenous sediment with a major influx of terrigenous material. It is now well established that an episode of major tectonic activity commenced around the North Pacific margin during the late Oligocene through mid-Miocene interval manifested by the formation of numerous Neogene marine basins along the Pacific Coast Allison (1964), Smith (1970), Ingle (1967Ingle ( , 1971Ingle ( ,1972Ingle ( , 1973, Asano et al (1969), andTiffin et al (1972). Note that absolute thicknesses are not given on this diagram.…”

“…Stratigraphic variations of these latter benthonic microfossils have in fact been used by Kleinpell (1938), Natland (1957), and Mallory (1959) to define the well-known provincial stages of the California Tertiary and Quaternary. However, the utility of stage designations based on benthonic species is tempered by the climatically induced faunal migrations and the rather narrow ecologic tolerances of these animals leading to time-transgressive facies problems (Bandy, 1967;Ingle, 1967;Steineck and Gibson, 1971). …”