Needmore Shale

Needmore Formation
Stratigraphic range: Emsian[1]
Typesedimentary
UnderliesMarcellus Shale and Millboro Shale
OverliesOriskany Formation
Lithology
Primaryshale
Location
RegionAppalachian Mountains
CountryUnited States
ExtentMaryland, Pennsylvania, Virginia, and West Virginia
Type section
Named forNeedmore, Pennsylvania
Named byWillard and Cleaves, 1939[2]

The Devonian Needmore Formation or Needmore Shale is a mapped bedrock unit in Pennsylvania, Maryland, Virginia, and West Virginia.

Description

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

DeWitt and Colton (1964) identified brachiopods (Coelospira acutiplicata, Eodevonaria arcuata), trilobites (Viaphacops cristata), and ostracods (Favulella favulosa) in the Needmore.[3]

Notable Exposures

Type locality is between Needmore and Warfordsburg in southern Fulton County, Pennsylvania.

Age

Relative age dating places the Needmore in the middle Devonian.

References

  1. ^ Paleozoic Sedimentary Successions of the Virginia Valley & Ridge and Plateau
  2. ^ 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.
  3. ^ 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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