The

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...

Needmore Formation or Needmore Shale is a mapped

bedrock In geology, bedrock is solid Rock (geology), rock that lies under loose material (regolith) within the crust (geology), crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface mater ...

unit in

Pennsylvania Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...

Maryland Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to ...

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...

, and

West Virginia West Virginia is a state in the Appalachian, Mid-Atlantic and Southeastern regions of the United States.The Census Bureau and the Association of American Geographers classify West Virginia as part of the Southern United States while the Bur ...

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 Fulton County is the name of eight counties in the United States of America. Most are named for Robert Fulton, inventor of the first practical steamboat: *Fulton County, Arkansas, named after Governor William Savin Fulton *Fulton County, Georgia *F ...

, Pennsylvania. They considered it part of the Onondaga Group. 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.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

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Fossils

DeWitt and Colton (1964) identified

brachiopods Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, whi ...

(''Coelospira acutiplicata'', ''Eodevonaria arcuata''),

trilobites Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the At ...

(''

Phacops ''Phacops'' is a genus of trilobites in the order Phacopida, family Phacopidae, that lived in Europe, northwestern Africa, North and South America and China from the Late Ordovician until the very end of the Devonian, with a broader time range d ...

cristata''), and

ostracods Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typical ...

(''Favulella favulosa'') in the Needmore.

Notable Exposures

Type locality is between Needmore and Warfordsburg in southern

, Pennsylvania.

Age

Relative age dating places the Needmore in the middle

References

Geologic formations of Pennsylvania Geologic formations of Maryland Geologic formations of Virginia Geologic formations of West Virginia Devonian System of North America Devonian geology of Pennsylvania Devonian Maryland Devonian geology of Virginia Devonian West Virginia Emsian Stage Limestone formations of the United States {{Maryland-geologic-formation-stub