NYSM locality 5933 (Ordovician of the United States)

Also known as Steves Farm section

Where: Washington County, New York (43.5° N, 73.4° W: paleocoordinates 31.8° S, 67.5° W)

• coordinate estimated from map

• small collection-level geographic resolution

When: Rochdale Formation (Beekmantown Group), Stairsian (485.4 - 478.6 Ma)

• "upper Rochdale Formation"

•"As concluded by Landing & Westrop (2006, p. 967), the Rochdale Formation is the senior synonym of the ‘Fort Ann Formation’, a unit for which a type section was never specified and which was named for a village that is actually located on Late Ordovician synorogenic flysch. Further north in western Vermont, the Bascom Formation (Cady, 1945) includes three divisions that indicate lateral equivalency and junior synonymy with the upper Tribes Hill, Rochdale and Fort Cassin formations (Landing, Westrop & Van Aller Hernick, 2003)." (Kröger & Landing, 2008 p. 492)

• formation-level stratigraphic resolution

Environment/lithology: shallow subtidal; burrowed, pebbly, shelly/skeletal lime mudstone

• "These thrombolitic- and intraclast dominated horizons are very similar to the cephalopod bearing beds of the underlying upper Tribes Hill Formation (Kröger & Landing, 2007) and represent the shoaling interval of a highstand systems tract."
• "The entire Rochdale section represents a deepening–shoaling, macroscale sequence with several subordinate cycles. In the lower 6.4 m, silty, locally microcross-bedded dolostone without shelly macrofaunas dominates, and yields sparse conodonts referable to the Low Diversity Interval or lower Macerodus dianae Zone (Landing, Westrop & Van Aller Hernick, 2003). Above a covered interval (6.4–13.7 m), fossiliferous dolostones and dolomitic limestones appear immediately north of the transformer station, and the lowest thrombolites occur in an intraclast matrix at 18 m. Cephalopods are very rare, and are only known from a few poorly preserved bassleroceratid fragments from beds at 15 m and 16 m above the base of the succession." Higher up "the section consists of several sequences formed of biostromal thrombolites in intraclast pack- to grainstone matrix, which are topped by laminated or cross-bedded intraclast-pebble-rich limestones with teepee structures. The top of the Rochdale Formation is a laminated, quartzose dolostone with chert-filled vugs after evaporites."

Size class: macrofossils

Preservation: cast

Collected by R. H. Flower; reposited in the NYSM

Collection methods: acetic

Primary reference: B. Kröger and E. Landing. 2008. Onset of the Ordovician cephalopod radiation - evidence from the Rochdale Formation (middle Early Ordovician, Stairsian)in eastern New York. Geological Magazine 145(4):490-520 [B. Kröger/B. Kröger]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 89504: authorized by Björn Kröger, entered by Torsten Liebrecht on 26.05.2009

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Cephalopoda
 Tarphycerida - Estonioceratidae
Aphetoceras sp.
Aphetoceras sp. Hyatt 1894
NYSM 17515