The Devonian Needmore Formation or Needmore Shale is a mapped bedrock unit in Pennsylvania, Maryland, Virginia, and West Virginia.
| 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] |
Description edit
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]
Fossils edit
DeWitt and Colton (1964) identified brachiopods (Coelospira acutiplicata, Eodevonaria arcuata), trilobites (Viaphacops cristata), and ostracods (Favulella favulosa) in the Needmore.[3]
Notable Exposures edit
Type locality is between Needmore and Warfordsburg in southern Fulton County, Pennsylvania.
Age edit
Relative age dating places the Needmore in the middle Devonian.
References edit
- ^ Paleozoic Sedimentary Successions of the Virginia Valley & Ridge and Plateau
- ^ a b Willard, Bradford, and Cleaves, A.B., 1939, Ordovician-Silurian relations in Pennsylvania: Geological Society of America Bulletin, v. 50, no. 7, p. 1165-1198.
- ^ a b deWitt, W. Jr., and Colton, G. W., 1964, Bedrock geology of the Evitts Creek and Pattersons Creek Quadrangles, Maryland, Pennsylvania, and West Virginia: U.S. Geological Surveys Bull. 1179, pl 1 and 2. [1]
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