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词条 Needmore Shale
释义

  1. Description

     Fossils  Notable Exposures 

  2. Age

  3. References

{{Infobox rockunit
| name = Needmore Formation
| image =
| caption =
| type = sedimentary
| age = Emsian[1]
| period = Emsian
| prilithology = shale
| otherlithology =
| namedfor = Needmore, Pennsylvania
| namedby = Willard and Cleaves, 1939[2]
| region = Appalachian Mountains
| country = United States
| coordinates =
| unitof =
| subunits =
| underlies = Marcellus Shale and Millboro Shale
| overlies = Oriskany Formation
| thickness =
| extent = Maryland, Pennsylvania, Virginia, and West Virginia
| area =
| map =
| map_caption =
}}

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 (Phacops 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. ^[https://vtechworks.lib.vt.edu/bitstream/handle/10919/19078/Read%20and%20Eriksson.pdf?sequence=1 Paleozoic Sedimentary Successions of the Virginia Valley & Ridge and Plateau]
2. ^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. ^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.  
{{Chronostratigraphy of Maryland}}{{Chronostratigraphy of Pennsylvania}}{{Chronostratigraphy of Virginia}}{{Stratigraphic column of West Virginia}}{{Maryland-geologic-formation-stub}}

11 : Limestone formations of the United States|Devonian System of North America|Devonian geology of Pennsylvania|Devonian Maryland|Devonian geology of Virginia|Devonian West Virginia|Geologic formations of Pennsylvania|Geologic formations of Maryland|Geologic formations of Virginia|Geologic formations of West Virginia|Emsian

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