F92 - Silverado Formation, Santa Ana Mountains (Paleocene of the United States)

Also known as USGS# 18988

Where: Orange County, California (33.9° N, 117.7° W: paleocoordinates 37.5° N, 98.2° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Silverado Formation, Thanetian (59.2 - 56.0 Ma)

• The type section suggests a thickness of around 350 m for the Silverado Formation, which lies unconformably upon the Late Cretaceous Williams Formation and Ladd Formation, and is overlain unconformably by the Santiago Formaton. The Silverado Formation is given a Paleocene age on the basis of macrofauna (sparse index taxa), but more finely assigned by McCulloh et al. (2000) to the Martinez stage = Thanetian. Calcareous nannoplankton zone CP7-CP; Planktonic foraminifera zone P4-P5; Ynezian foram zone. The Silverado Formation is correlative to the lower-middle Santa Susana Formation.

• bed-level stratigraphic resolution

Environment/lithology: marine; fine-grained, medium, shelly/skeletal sandstone

• The contact below the Silverado Formation represents an episode of deformation and extensive erosion and deep weathering between the deposition of the late Cretaceous rocks and the Paleocene strata.
• Fine-medium grained sandstone.

Size class: macrofossils

Reposited in the USGS

Collection methods: quarrying,

• Collected by D.M. Kinney, J.E. Schoellhamer, and W.P. Woodring. Material likely to be reposited in USGS Menlo Park collections or USNM.

Primary reference: J. E. Schoellhamer, J. G. Vedder, R. F. Yerkes and D. M. Kinney. 1981. Geology of the Northern Santa Ana Mountains, California. United States Geological Survey Professional Paper 420(D):1-109 [J. Alroy/J. Alroy/R. McClees-Funinan]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 52602: authorized by Austin Hendy, entered by Austin Hendy on 11.08.2005

Creative Commons license: CC BY (attribution)

Taxonomic list

• Fossils identified by Stewart (1954, 1955) and Moore (1959). Relatively good nomenclature
Gastropoda
 Cerithioidea - Turritellidae
Turritella pachecoensis Stanton 1896 turret shell
 Sorbeoconcha - Naticidae
Bivalvia
 Arcida - Glycymerididae
Glycymerita major Stanton 1896 clam
Subspecies: Glycymeris veatchii major
 Mytilida - Mytilidae
Brachidontes sp. Swainson 1840 mussel
 Cardiida - Veneridae
 Lucinida - Lucinidae
? Claibornites turneri Stanton 1896 clam
 Carditida - Crassatellidae
Crassatella unioides Stanton 1896 clam
 Nuculanida - Nuculanidae
Nuculana cf. gabbii Conrad 1866 pointed nut clam