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The Ordovician

Ordovician

The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...

 Bellefonte Formation (Obf) is a mapped bedrock unit in central Pennsylvania

Pennsylvania

The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...

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Description

The Bellefonte is defined as a medium-gray, brownish-weathering, medium-bedded dolomite

Dolomite

Dolomite is a carbonate mineral composed of calcium magnesium carbonate CaMg2. The term is also used to describe the sedimentary carbonate rock dolostone....

 and minor sandstone

Sandstone

Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...

. The very fine grained Tea Creek Member lies above, and the crystalline Coffee Run Member lies below.

Depositional Environment

Deposition of formations such as the Bellefonte Dolomite occurred in environments equivalent to the modern Bahama lagoons, east of Miami.

Age

Relative age dating of the Bald Eagle places it in the Ordovician

Ordovician

The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...

 period. It rests atop the Axemann Formation (Oa), or the Nittany Formation, for example between Tyrone

Tyrone, Pennsylvania

Tyrone is a borough in Blair County, Pennsylvania, northeast of Altoona, on the Little Juniata River. Tyrone was of considerable commercial importance in the twentieth century. It was an outlet for the Clearfield coal fields, and it was noted for the manufacture of paper products. There were...

 and Water Street, Pennsylvania

Water Street, Pennsylvania

Water Street is a small unincorporated village in the Canoe Valley of Morris Township, part of Huntingdon County, Pennsylvania, United States. The Frankstown Branch Juniata River runs north along the west foot of the Tussey Mountain ridge to the village, before turning east along U.S. Route 22,...

, where the Axemann is missing, and the Loysburg Formation of interbedded limestone and dolomite conformably overlies the Bellefonte Formation.