Where: Ventura County, California (34.3° N, 118.7° W: paleocoordinates 35.0° N, 104.7° W)
• coordinate estimated from map
• outcrop-level geographic resolution
When: Llajas Formation, Lutetian (47.8 - 41.3 Ma)
• Immediately below the "Stewart Bed", middle of the Llajas Formation, "Domengine" stage, top of CP12a calcareous nannoplankton zone, lower Lutetian stage, Middle Eocene, C21r chron.
• bed-level stratigraphic resolution
Environment/lithology: transition zone or lower shoreface; lithified, argillaceous siltstone and bioturbated sandstone
• The "Stewart bed" is located in a section of transition from shallow-marine to outer slope and shelf facies. A nearshore environment is interpreted for that portion of the shallow-marine (transgressive) facies which consists of laminated beds alternating with bioturbated beds. In such cases, the finely laminated sand represents storm-influenced stratification, and the biogenic reworking is the inter-storm activity. Shell fragments commonly are concentrated as channel lags in surge channels. Fossils were apparently subjected to wave action because the apices of elongate shells such as Turritella are bimodally oriented in opposite directions. The deeper the water, the less amount of laminated sandstone and the more amount of bioturbated sandstone. Such areas, which were farther below effective wave base, existed 1) where the shallow-marine (transgressive) facies grades into the outer shelf to slope facies and 2) in the shallow-marine (regressive) facies. One of the deepest-water shallow-marine beds was the "Stewart bed."
• Alternating laminated and bioturbated sandstones grading into muddy siltstone.
Size class: macrofossils
Reposited in the LACM
• Collected by R.L. Squires, (1978) and CSUN paleontology classes in the 1980's-1990's and G. Slak (1997-1998)
Primary reference: R. L. Squires. 2001. Additions to the Eocene megafossil fauna of the Llajas Formation, Simi Valley, southern California. Contributions in Science (Natural History Museum of Los Angeles County) 489:1-40 [A. Miller/A. Hendy/A. Hendy]more details
Purpose of describing collection: taxonomic analysis
PaleoDB collection 51922: authorized by Austin Hendy, entered by Austin Hendy on 04.07.2005, edited by Jonathan Marcot and Patricia Holroyd
Creative Commons license: CC BY (attribution)
• Exhaustive for mollusca, corals, arthropoda, and includes other groups where obvserved; list compiled from meticulous search of the invert collections at the LACM, private collections and fieldwork.
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