Knox Group, Upper Part (Ordovician of the United States)

Where: Washington County, Virginia (36.8° N, 82.3° W: paleocoordinates 30.6° S, 73.0° W)

• coordinate stated in text

• local area-level geographic resolution

When: Arenigian (478.6 - 468.1 Ma)

• Knox is a Group name. Authors state that the formations in the area are discontinuous outcrops and thus do not feel confident in using more precise nomenclature. AGE: Arenigian; refined from Early Ordivician by A. Hendy (6/2009) on the basis of biostratigraphic data.

• formation-level stratigraphic resolution

Environment/lithology: shallow subtidal; lithified, gray, cherty/siliceous dolomite and limestone

• light-gray, fine to coarse grained, cherty dolomite with minor beds of blue-gray limestone;; zones of collapse breccia with pockets of gray and maroon shale in upper part; abundant white chert float with dolomolds; moderately fossiliferous in some limestone beds.

Primary reference: C. S., J.r. Bartlett and H. W. Webb. 1971. Geology of the Bristol and Wallace quadrangles, Virginia. Virginia Division of Mineral Resources Report of Investigations 25:1-93 [J. Alroy/M. Sommers/P. Wagner]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 6980: authorized by John Alroy, entered by Mike Sommers on 18.04.2000, edited by Pete Wagner

Creative Commons license: CC BY (attribution)

Taxonomic list

unclassified
  -
Cephalopoda
 Nautiloidea -
Nautiloidea indet. Agassiz 1847 nautiloid
fragments
 Tarphycerida - Tarphyceratidae
Campbelloceras sp. Ulrich and Foerste 1936
Gastropoda
 Murchisoniina -
Murchisonioidea indet. Koken 1896 snail
 Murchisoniina - Hormotomidae
Hormotoma sp. Salter 1859 snail
 Euomphalina - Helicotomidae
? Lophonema sp. Purdue and Miser 1916 snail
 Euomphalina - Lesueurillidae
Eccyliopterus sp. Remelé 1888 snail
cf. Pararaphistoma sp. Vostokova 1955 snail
 Euomphalina - Raphistomatidae
"Ceratopea sp." = Ceratopea, "Roubidouxia sp." = Ceratopea
"Ceratopea sp." = Ceratopea Ulrich 1911 snail
"Roubidouxia sp." = Ceratopea Ulrich 1911 snail
 Euomphalina - Ophiletidae
Lecanospira compacta Salter 1859 snail
Trilobita
  -
Trilobita indet. Walch 1771 trilobite
fragments