West Slope of Derry Hills, Arrey Formation, Collection 2a (Carboniferous of the United States)

Where: Sierra County, New Mexico (32.8° N, 107.3° W: paleocoordinates 7.5° S, 46.1° W)

• small collection-level geographic resolution

When: Arrey Formation (Green Canyon Group), Carboniferous (358.9 - 298.9 Ma)

• Derry series is divided into 2 groups and 4 formations. At the type locality, the Derryan consists of alternating limestone (80 %) and shales (20%), approximately 127 feet thick, lying unconformably upon Devonian shale. Unit 2a = 8.7 ft

• group of beds-level stratigraphic resolution

Environment/lithology: marine; lithified, gray, cherty/siliceous limestone

• Unit 2a: Limestone, gray, hard, fine-grained, extremely cherty; some yellow-banded chert; locally, crinoid stems in limestone and bryozoan impressions in chert; weathers rough; cliff-forming

Size classes: macrofossils, microfossils

Primary reference: J. L. Gehrig. 1958. Middle Pennsylvanian Brachiopods From the Mud Springs Mountains and Derry Hills, New Mexico. State Bureau of Mines and Mineral Resources, Memoir 3 1-24 [T. Olszewski/K. Nell]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 9953: authorized by Tom Olszewski, entered by Katrina Nell on 20.02.2001

Creative Commons license: CC BY (attribution)

Taxonomic list

• Except for noting the presence of crinoids and bryozoans impressions, only brachiopods and fusulinids reported.
Foraminifera
 Fusulinoidea - Eostaffellidae
Strophomenata
 Productida - Productidae
Dictyoclostus sp. Muir-Wood 1930
 Productida -
 Strophomenida - Chonetidae
Rhynchonellata
 Spiriferida - Trigonotretidae
Neospirifer sp. Fredericks 1919
 Spiriferida - Spiriferidae
"Spirifer occidentalis" = Anthracospirifer occiduus
"Spirifer occidentalis" = Anthracospirifer occiduus Sadlick 1960
 Orthida - Rhipidomellidae
Rhipidomella carbonaria Shumard and Swallow 1858