Where: Ventura County, California (34.3° N, 118.7° W: paleocoordinates 35.1° N, 104.6° W)
• coordinate estimated from map
• outcrop-level geographic resolution
When: Llajas Formation, Lutetian (47.8 - 41.3 Ma)
• From the "Domengine" horizon of the Eocene of Simi Valley.
• group of beds-level stratigraphic resolution
Environment/lithology: transition zone or lower shoreface; lithified, fine-grained, brown, yellow 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."
Size class: macrofossils
Collected by R. B. Stewart; reposited in the UCMP
Primary reference: H. G. Schenck. 1931. Cephalopods of the genus Aturia from western North America. University of California Publications, Bulletin of the Department of Geological Sciences 19:435-490 [M. Clapham/K. Okamoto/M. Clapham]more details
Purpose of describing collection: taxonomic analysis
PaleoDB collection 166460: authorized by Matthew Clapham, entered by Kristina Okamoto on 14.02.2015, edited by Jonathan Marcot and Patricia Holroyd
Creative Commons license: CC BY (attribution)
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