Clatsop (UGSG 5323) - #19 (Moore, 1963) (Miocene of the United States)

Also known as Locality #19 (Moore, 1963); USGS 5323

Where: Clatsop County, Oregon (46.2° N, 123.8° W: paleocoordinates 46.0° N, 119.2° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Middle Shale Member (Astoria Formation), Middle Miocene (16.0 - 11.6 Ma)

• From the lower part of the Middle Shale Member, less than 100 ft thick. Astoria Formation has been used as a name for almost all of the marine middle Miocene sedimentary rocks of Washington and Oregon although these correlations are poorly constrained. The formation has been divided into three members: a lower sandstone, a shale, and an upper sandstone. These rocks form the northern limb of a syncline, the asis of which is exposed east of Astoria, and the syncline trends NE and plunges to the SW. The Astoria Formation is intermittently exposed; theya re faulted and exposures are interupted by volcanic rocks and slides. The maximum thickness of any exposure is 25 feet.

• bed-level stratigraphic resolution

Environment/lithology: coastal; lithified, concretionary, tuffaceous, sandy shale

• Astoria Formtaion is faulted and interupted in exposure by volcanic rocks and land slides.
• Shale alternates with sandstone. The shale is bentonitic. Contains numerous fossils, in some places embedded in calcareous nodules, while in other places they are compressed.

Size class: macrofossils

Preservation: concretion, replaced with other

Reposited in the CAS, USNM

Collection methods: salvage, quarrying, surface (float),

• Collected by R.F. Rogers, 1910. Collections reside in the Californian Academy of Sciences, the U.S. National Museum, and presumably the USGS.

Primary reference: E. J. Moore. 1963. Miocene marine mollusks from the Astoria Formation in Oregon. United States Geological Survey Professional Paper 419 [A. Miller/A. Hendy/A. Hendy]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 39595: authorized by Austin Hendy, entered by Austin Hendy on 31.05.2004

Creative Commons license: CC BY (attribution)

Taxonomic list

• Exhaustive for mollusca
Bivalvia
 Pectinida - Propeamussiidae
Parvamussium astoriana mud scallop
[entered as Paramussium astoriana]
 Lucinida - Thyasiridae
"Thyasira bisecta" = Conchocele conradii
"Thyasira bisecta" = Conchocele conradii Rosenkrantz 1942 clam
 Nuculida - Nuculidae
 Protobranchia - Nuculanidae
Litorhadia astoriana pointed nut clam
Gastropoda
 Cephalaspidea - Retusidae
"Cylichnina petrosa" = Retusa (Cylichnina)
"Cylichnina petrosa" = Retusa (Cylichnina) snail