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Warren O. Addicott

Publications and source records attributed to Warren O. Addicott.

14 recordsLinked to original sources
USGS1976

New molluscan assemblages from the upper member of the Twin River Formation, western Washington: Significance in Neogene chronostratigraphy

New molluscan assemblages of provincial early Miocene age from a previously unrecognized fossiliferous interval of 400 to 500 metres in the uppermost part of the Twin River Formation, western Washington, are referable to the upper part of the "Blakeley" [or Matlockian] Stage. The new biostratigraphic data provide, for the first time, definition of the uppermost part of the "Blakeley" Stage and the boundary between it and an unnamed stage of late early Miocene age represented by the Clallam Formation and its megafauna. In contradistinction to earlier studies, the upper boundary of the "Blakeley" Stage does not coincide with the upper boundary of the Zemorrian Stage of the foraminiferal chronology, the "Blakeley" boundary being at least 45 m higher and possibly much more. Nearly 60 species of mollusks from the upper few hundred metres of the Twin River Formation are recognized herein, and 40 of these are illustrated. Six species are previously undescribed.

Washington↗
USGS1973

Pliocene marine fossils in the Paso Robles Formation, California

Marine invertebrates from the Paso Robles Formation recently discovered near Atascadero, Calif., indicate that the basal part of this chiefly nonmarine deposit is of provincial early Pliocene age. Heretofore the lack of direct fossil or radiometric evidence of the age of the Paso Robles has made it a difficult unit to place in the late Cenozoic history of the Coast Ranges. The assemblage is dominated by Ostrea vespertina and by Nettastomella rostrata , a rock-boring bivalve; its mode of preservation indicates that the fossils are in place and have not been recycled from older marine formations. This occurrence suggests that during the early Pliocene a seaway connected the present southern Salinas Valley area with the northern part of the Santa Maria basin; the fossils occur about halfway between the southernmost exposures of the Pancho Rico Formation near San Miguel and fossiliferous strata east of Pismo Beach, both marine units of early Pliocene age.

California↗
USGS1969

Cretaceous, Tertiary, and early Pleistocene rocks from the continental margin in the Bering Sea

Rocks dredged from the continental margin in eastern Bering Sea in and near the Pribilof Canyon indicate that the acoustic basement represents the upper surface of thoroughly lithified turbidite beds of graywacke and siltstone of Late Cretaceous age. The stratified sequence covering the acoustic basement is gently deformed and includes marine clastic and diatomaceous sediments ranging in age from middle or late Miocene through early Pleistocene. Dense argillite, siltstone, and calcareous sandstone of early Tertiary age in and near the Zhemchug Canyon probably represent an older part of this sequence. The main layered sequence accumulated above the acoustic basement in shallow water, and, because the older beds now lie as much as 1000 m below sea level, the continental margin must have undergone considerable subsidence during late Tertiary and Quaternary time. A rich pollen flora indicates that the shoreline lay only a few tens of kilometers away from the site of the Pribilof Canyon during late Miocene time.

Alaska↗
USGS1968

Age of first marine terrace near Santa Cruz, California

Five species of shallow neritic Pleistocene mollusks from a central California marine terrace give these Th 230 /U 238 ages: 88,000; 68,000; 76,000; 16,000; 100,000; 91,000 (from data in Blanchard and others, 1967). With one exception, the ages fall between 68,000 and 100,000 years. This broad grouping of ages, its general agreement with dates from elsewhere, and geologic evidence suggest that the sea was relatively high in central California sometime during this interval.

California↗