UO 80, Eugene (Eocene of the United States)

Where: Lane County, Oregon (44.0° N, 123.0° W: paleocoordinates 44.4° N, 110.8° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Eugene Formation, Priabonian (38.0 - 33.9 Ma)

• Eugene Formation can be subdivided faunally: a lower unit correlating to the Keasey Fm, a middle unit correlating to the Gries Ranch Beds of WA, and a upper unit correlated with the Pittsburg Bluff Fm. Thickness of formation may be up to 15,000 feet, but probably around 5,000 feet. Most of the outcrops are scattered so it is difficult to estimate their relative stratigraphic placement

• bed-level stratigraphic resolution

Environment/lithology: transition zone or lower shoreface; lithified, tuffaceous, brown, gray, blue sandstone and tuffaceous, brown, gray, blue siltstone

• Retallack et al. (2000): Near-shore, shallow-marine environments are indicated by sedimentary structures such as hummocky cross-bedding, shallow water trace fossils such as Planolites and Thalassinoides and common glauconite and phosphate nodules (Mears, 1989).

•Hickman (1969): Several lines of evidence suggest that most of the Eugene Formation was deposited in shallow water, at depths no greater than 30 fathoms. The coarse, tuffaceous, and arkosic character of many beds and the interfingering of the Eugene Formation with non-marine tuffaceous rocks to the east and south indicates the proximity of the Oligocene shoreline. Although mollusks are generally not good indicators of depth, genera such as Panopea, Modiolus, Solen, and Spisula are presently restricted to depths of less than 40 fathoms. The high diversity of the benthonic fauna is an indication that the environment was not one of a bay or otherwise highly restricted environment. The absence of planktonic forms is typical of turbid, near-short environments. In the same units with these relatively undisturbed infauna! assemblages there are occasional thin layers of concentrated shell material which show definite signs of reworking and current sorting. The layers range from 1 to 10 cm in thickness and cannot be traced over great distances. The shells in these layers are small and include an admixture of infaunal and epifaunal species. The shells show little sign of wear or breakage, but many of the pelecypod valves are disarticulated, indicating some degree of transport. The scaphopods in these layers show parallel alignment by the current. There is also evidence that currents were intermittent and fluctuating in strength: the assemblages contain varying percentages of large shells mixed in with the smaller ones, and in some places there are higher proportions of broken and abraded shell debris mixed in.

• Tuffaceous and highly feldspathic sandstone or siltstone which is bluish-gray to olive when fresh and weathers to a buff or orange-brown color. Gray sandstone and siltstone beds may range from several to 50 feet in thickness and are interbedded with minor amounts of sandy sahel and clay shale, occasional beds of conglomerate, and thin lenses of gray or buff-colored volcanic ash

Size class: macrofossils

Preservation: mold/impression, trace

Reposited in the CAS

Collection methods: quarrying,

• Collections held at University of Oregon, University of California, Californian Academy of Sciences (CAS), United States Geological Survey (USGS), and Stanford University (NP).

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 39002: authorized by Austin Hendy, entered by Austin Hendy on 18.05.2004

Creative Commons license: CC BY (attribution)

Taxonomic list

• Exhaustive for mollusca
Bivalvia
 Nuculanida - Nuculanidae
"Nuculana washingtonensis" = Nuculana (Saccella) washingtonensis
"Nuculana washingtonensis" = Nuculana (Saccella) washingtonensis Weaver 1916 pointed nut clam
 Arcida - Arcidae
Anadara (Anadara) sp. Gray 1847 ark
 Mytilida - Crenellidae
Crenella ? sp. Brown 1827 clam
 Solenida - Solenidae
 Thraciida - Thraciidae
"Thracia condoni" = Thracia (Cetothrax) condoni
"Thracia condoni" = Thracia (Cetothrax) condoni Dall 1909 clam
 Cardiida - Mactridae
"Spisula eugenensis" = Mactromeris eugenensis
"Spisula eugenensis" = Mactromeris eugenensis Clark 1925 clam
 Cardiida - Veneridae
Macrocallista sp. n. sp. Meek 1876 venus clam
Pitar (Pitar) sp. n. sp. Römer 1857 venus clam
Pitar (Pitar) dalli Weaver 1916 venus clam
 Cardiida - Cardiidae
Parvicardium eugenense Clark 1925 cockle
 Cardiida - Tellinidae
Tellina aduncanasa tellin clam
Tellina (Moerella) lincolnensis Weaver 1916 tellin clam
Tellina pittsburgensis Clark 1925 tellin clam
 Pholadida - Pholadidae
Martesia sp. Sowerby 1824 clam
 Pholadida - Myidae
Mya (? Arenomya) kusiroensis Nagao and Inoue 1941 softshell clam
 Lucinida - Lucinidae
Lucinoma acutilineata Conrad 1849 clam
Scaphopoda
 Dentaliida - Dentaliidae
Gastropoda
 Epitonioidea - Epitoniidae
Acrilla (Ferminoscala) ? becki Durham 1937 wentletrap
Acrilla (Ferminoscala) dickersoni Durham 1937 wentletrap
Epitonium (Boreoscala) condoni Dall 1909 wentletrap
Subspecies: Epitonium (Boreoscala) condoni condoni
 Sorbeoconcha - Naticidae
Polinices washingtonensis Weaver 1916 moon snail
"Neverita thomsonae" = Glossaulax reclusiana Deshayes 1839 moon snail
Sinum obliquum Gabb 1864 moon snail
 Neogastropoda - Siphonaliidae
 Neogastropoda - Turridae
Gemmula bentsonae Durham 1944 turrid
 Neogastropoda - Ptychatractidae
Exilia lincolnensis Weaver 1916 snail
 Neogastropoda - Olividae
"Molopophorus fishii" = Ancilla fishii
"Molopophorus fishii" = Ancilla fishii Gabb 1866 olive snail
 Sorbeoconcha - Bursidae
Olequahia schencki Durham 1944 frog shell
 Neotaenioglossa - Calyptraeidae
Calyptraea diegoana Conrad 1855 slipper shell
 Opisthobranchia - Retusidae
Cylichnina turneri Effinger 1938 snail
Cephalopoda
 Nautilida - Aturiidae
Aturia angustata Conrad 1849