Lyons Gap on Walker Mountain (Ordovician of the United States)

Where: Smyth County, Virginia (36.8° N, 81.7° W: paleocoordinates 29.7° S, 62.1° W)

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

• Shuler (1915) described the material as coming from the Bays Sandstone, “ninety feet below the Clinch sandstone.” However, (Butts and Edmundson 1943) and an unpublished geological map of the area (Web and Whitlock 2003) do not show any Bays Formation in the area. Instead, the unit is likely the Martinsburg, possibly the Juniata. It is described as an “argillaceous sandstone with a pronounced brick red color”; associated fauna includes the bivalve Ambonychia and the brachiopod Orthorhynchula linneyi (Shuler 1915). The latter is associated with the upper part of the Martinsburg in this area whereas the Juniata is unfossiliferous (Butts and Edmonson 1943(Kreisa and Springer 1987)).

Environment/lithology: marine; lithified, red, argillaceous sandstone

• argillaceous sandstone with a pronounced brick red color

Size class: macrofossils

Primary reference: E.W. Shuler. 1915. A new Ordovician eurypterid. American Journal of Science 39:551-554 [R. Plotnick/R. Plotnick]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 204960: authorized by Roy Plotnick, entered by Roy Plotnick on 01.10.2019

Creative Commons license: CC BY (attribution)

Taxonomic list

Euchelicerata
 Eurypterida - Megalograptidae
Megalograptus alveolatus Shuler 1915 eurypterid
Bivalvia
 Myalinida - Ambonychiidae
"Ambonychia radiata" = Byssonychia radiata
"Ambonychia radiata" = Byssonychia radiata Hall 1847 clam
Rhynchonellata
 Rhynchonellida - Orthorhynchulidae