Abstract: Additions to the Molluscan Fauna of the Eocene Juncal? Formation, Lockwood Valley, Ventura County, Southern California
SQUIRES, RICHARD, California State University, Northridge, Northridge, CA
Recent recollecting of localities and the discovery of specimens of shallow-marine mollusks stored at the Natural History Museum of Los Angeles County revealed 11 species of gastropods and one species of bivalve, all previously unreported from the sparsely fossiliferous Juncal? Formation along the north side of Lockwood Valley. The gastropods are Calorebama dilleri lineata, Cryptoconus cooperi, Eocypraea (Eocypraea) castacensis, Hipponix n. sp.?, Keliostoma californicus, Neverita (N.) globosa, Strepsidura ficus, Tornatellaea rosa, Turritella andersoni lawsoni, Turritella uvasana applinae, and Velates perversus; the bivalve is Corbula (Caryocorbula) dickersoni.
The entire 600-m-thick Juncal? Formation in Lockwood Valley was previously assigned to the middle lower Eocene west-coast molluscan "Capay Stage," on the basis of the presence of Turritella andersoni. The upper 100 m, however, can now be assigned to the upper lower to lower middle Eocene "Domengine Stage," on the basis of the presence of Turritella andersoni lawsoni. The specimens of this subspecies represent newly found material, as well as reevaluated poorer preserved specimens that were previously collected.
Although the locality information for Turritella uvasana applinae is poorly known, it is likely that this turritellid is also from the upper 100 m of the formation because this subspecies is diagnostic of the "Domengine Stage." The other above-listed mollusks were found only in the upper 100 m of the formation.
AAPG Search and Discovery Article #90911©2000 AAPG Pacific Section and Western Region Society of Petroleum Engineers, Long Beach, California