Needmore Formation

Needmore Formation
Stratigraphic range: Devonian
Type sedimentary
Lithology
Primary shale
Location
Named for Needmore, Pennsylvania
Named by Willard and Cleaves, 1939[1]
Region Appalachian Mountains
Country United States
Extent Pennsylvania

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

Contents

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.[1]

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 as approximately 150 feet.[2]

Fossils

DeWitt and Colton (1964) identified brachiopods (Coelospira acutiplicata, Eodevonaria arcuata), trilobites (Phacops cristata), and ostracods (Favulella favulosa) in the Needmore.[2]

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. ^ 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.
  2. ^ 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]