Isle La Motte, Division C, Valcour Fm (Ordovician of the United States)

Where: Vermont (44.9° N, 73.3° W: paleocoordinates 28.0° S, 54.6° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Valcour Formation (Chazyan Group), Chazyan (470.0 - 457.3 Ma)

• "Group C" of the Chazy Formation (Upper Chazy).

• formation-level stratigraphic resolution

Environment/lithology: lithified limestone

• Details of the divisions at each of the localities from which each specimen listed are not given, thus I will give a complete description of lithologies summarized by Ruedemann for the formation at two different localities. “Section of the Chazy beds at Valcour in ascending order: The Chazy beds at Valcour form a low anticline. B1, a hard, compact, gray limestone, exposed at water edge, on land of Ezra Day. 2 feet of its top exposed. B2, same rock. 6 inches. B3, gray, shaly impure limestone with mud seams; very fossiliferous. 1 foot 4 inches. B4, more crystalline limestone with darker shaly intercalations. 1 foot 10 inches. Contains numerous small bryozoan reefs and other fossils; also many cephalopods in its upper layer (just north of fence diving lands of George and Ezra Day). B5, darker, impure shaly limestone. 1 foot 6 inches. Contains some large nautiloids. B6, a gray shaly limestone, 3 feet, containing a rich fauna (Bolboporites, Malocystites, brachipods, trilobites). B7, series of heavier, dark gray beds with abundant plates of Palaocystites. 7a-10 inches, barren; 7b-14 inches, in lower 3 inches full of trilobites; 7c-3 feet 6 inches, barren; 7c2-8 inches, hard crystalline gray limestone with trilobites. B8, 5 ½ feet of dark shaly limestone, nearly bluish gray and very fossiliferous, containing orthoceracones. Since we can do no better than base our future stratigraphic work on the larger lithologic divisions recognized by Brainerd and Seely in the Beekmantown formation at East shore ham Vt. And in the Chazy formation at Chazy village, we refer the fossils obtained at other places than the Valcour shore provisionally to those divisions.”

Size class: macrofossils

Primary reference: R. Ruedemann. 1906. Cephalopoda of the Beekmantown and Chazy formations of the Champlain Basin. Bulletin of the New York State Museum, Paleontology 14:389-611 [P. Wagner/K. Koverman/M. Uhen]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 42814: authorized by Pete Wagner, entered by Kimberly Koverman on 05.08.2004, edited by Pete Wagner

Creative Commons license: CC BY (attribution)

Taxonomic list

Cephalopoda
 Oncocerida - Oonoceratidae
 Oncocerida - Valcouroceratidae
"Cameroceras tenuiseptum" = Valcouroceras tenuiseptum, "Oonoceras seelyi" = Valcouroceras seelyi
"Cameroceras tenuiseptum" = Valcouroceras tenuiseptum Ruedemann 1906
"Oonoceras seelyi" = Valcouroceras seelyi Ruedemann 1906
 Endocerida - Endoceratidae
Cameroceras curvatum Ruedemann 1906
Vaginoceras oppletum Ruedemann 1906
 Bisonocerida - Proterovaginoceratidae
Perkinsoceras foerstei n. sp.1 Flower 1976
Rostroconchia
 Conocardiida - Bransoniidae
"Conocardium beecheri" = Pojetaconcha beecheri2
"Conocardium beecheri" = Pojetaconcha beecheri2 Raymond 1905
Gastropoda
 Bellerophontida - Bucaniidae
Bucania sulcatina2 Emmons 1842 snail