Walker Mountain 204 (W204) (Ordovician of the United States)

Where: Smyth County, Virginia (36.9° N, 81.5° W: paleocoordinates 29.8° S, 61.9° W)

• coordinate estimated from map

• small collection-level geographic resolution

When: Martinsburg Formation, Caradoc (458.4 - 449.5 Ma)

• Total unit thickness = 62.50 m

•Time interval = Trentonian-Maysvillian

•

•Stratigraphic and geologic descriptions based on Kreisa (1980)

• group of beds-level stratigraphic resolution

Environment/lithology: transition zone or lower shoreface; lithified shale and lithified, shelly/skeletal packstone

• Stratigraphic and geologic descriptions based on Kreisa (1980); within Kreisa's mixed clastic-carbonate platform facies
• shale (55%) and limestone (45%); shale varying from 60% at base of unit to 50% at to; limestone is skeletal packstone (15%) and calcisiltite and minor calcarenite (total 30%) with abundant terrigenous silt (few beds of siltstone); very thin to medium bedded, packstone-laminated bed couplets common, plane laminated and CWRL, but many calcisiltites are massive

Size class: macrofossils

Collection methods: bulk,

Primary reference: K. M. Layou. 2009. Ecological restructuring after extinction: the Late Ordovician (Mohawkian) of the eastern United States. Palaios 24:118-128 [K. Layou/K. Layou]more details

Purpose of describing collection: paleoecologic analysis

PaleoDB collection 85640: authorized by Karen Layou, entered by Karen Layou on 13.01.2009

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Trilobita
 Asaphida - Asaphidae
Isotelus sp.
Isotelus sp. Dekay 1824 trilobite
Strophomenata
 Strophomenida - Rafinesquinidae
Rafinesquina alternata
Rhynchonellata
 Orthida - Dalmanellidae
Dalmanella fertilis
Dalmanella fertilis Ulrich 1909