Needmore Formation | |
---|---|
Stratigraphic range: Emsian [1] | |
Type | sedimentary |
Underlies | Marcellus Shale and Millboro Shale |
Overlies | Oriskany Formation |
Lithology | |
Primary | shale |
Location | |
Region | Appalachian Mountains |
Country | United States |
Extent | Maryland, Pennsylvania, Virginia, and West Virginia |
Type section | |
Named for | Needmore, Pennsylvania |
Named by | Willard and Cleaves, 1939 [2] |
The Devonian Needmore Formation or Needmore Shale is a mapped bedrock unit in Pennsylvania, Maryland, Virginia, and West Virginia.
The Needmore Formation was originally described by Willard and Cleaves in 1939 as a dark- to medium-gray limy shale, based on exposures in southern Fulton County, Pennsylvania. They considered it part of the Onondaga Group. [2]
DeWitt and Colton (1964) described the Needmore as "soft calcareous medium dark-brownish-gray and greenish-gray shale and mudrock...and soft, slightly calcareous very fissile brownish-black shale" that is not resistant to weathering. They estimated its thickness in their study area (southern Bedford County, Pennsylvania, and most of Allegany County, Maryland) as approximately 150 feet. [3]
DeWitt and Colton (1964) identified brachiopods (Coelospira acutiplicata, Eodevonaria arcuata), trilobites ( Viaphacops cristata), and ostracods (Favulella favulosa) in the Needmore. [3]
Type locality is between Needmore and Warfordsburg in southern Fulton County, Pennsylvania.
Relative age dating places the Needmore in the middle Devonian.