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Geology of Pennsylvania
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Geology of Pennsylvania
The Geology of Pennsylvania consists of six distinct physiographic provinces, three of which are subdivided into different sections. Each province has its own economic advantages and geologic hazards and plays an important role in shaping everyday life in the state. From the southeast corner to the northwest corner of the state, they include: the Atlantic Plain Province, the Piedmont Province, the New England Province, the Ridge and Valley Province, the Appalachian Province, and the Central Lowlands Province.
A majority of the rocks in Pennsylvania exposed at the surface are sedimentary and were deposited during the Paleozoic Era. Almost all of the metamorphic and igneous rocks are confined to the southeast portion of the state. A total of four orogenies have affected the rocks of the Commonwealth including the Grenville orogeny, the Taconic orogeny, the Acadian orogeny, and the Appalachian orogeny. The Appalachian event has left the most evidence and has continued to shape the landscape of the state. The Pennsylvania terrain has also been affected by continental rifting during the Mesozoic era.
Pleistocene glaciers have also repeatedly visited the state over the last 100,000 years. These glaciers have left some evidence and carved out much of the landscape of the northern tier of the state.
A rock with high economic value from Pennsylvania is anthracite coal. Before mining began, there was an estimated 22.8 billion tons of anthracite in Pennsylvania. In 2001, 12 billion tons still remained in the ground, most of which was not economically feasible to mine. American geologists recognized the importance of Pennsylvania's coal region and named the Upper Carboniferous Period the Pennsylvanian Period because of the abundance of coal in the state. Despite this, Celestine was proposed as the state mineral in 2002. The proposal however, was not approved by the state legislature.
Pennsylvania is also home to the famous Drake Oil Well in Titusville which helped give rise to the modern oil industry and two brand name motor oils, Quaker State (now owned by Royal Dutch Shell) and Pennzoil. Pennsylvania also has reserves of natural gas from both deeply buried source rocks and coal-bed areas.
One of the smallest physiographic provinces in the state is confined to Philadelphia, Delaware, and Bucks counties along the Delaware River. Local relief is less than 200 feet (61 m) and much of the bedrock is buried under recent alluvial deposits. On the geologic map, "Trenton Gravel" is used to describe most of these sediments. Much of the alluvial sediments that exist here are sand, silt, and clays. The traditional boundary of the coastal plain is the Fall Line. The coastal plain in Pennsylvania was once home to thousands of acres of fresh water tidal marsh. This was important in the early development of Philadelphia and Chester. Many of the small tributaries to the Delaware have cut small but impressive gorges into the bedrock, including the Ridley Creek, the Chester Creek, and the Wissahickon Creek. Flash floods are becoming a local problem in the province.
The Piedmont in Pennsylvania is divided into three distinct sections: the Piedmont Uplands, the Piedmont Lowlands, and the Gettysburg-Newark Lowlands. Much of the Piedmont is becoming urbanized and developed. Some of the best farmland in the state is in this region, specifically Lancaster and Chester counties.
This section is characterized by the metamorphic rocks that provide much of the bedrock for this area. The oldest exposed rocks in Pennsylvania are found here and consist of the Baltimore Gneiss. These rocks have a complex history and a vast array of different minerals. They are similar in many respects to their cousins in northern and central Maryland, immediately to the south. Much of the rock was altered during the formation of Rodinia during the Grenville orogeny. These rocks eventually provided the platform for the deposition of sediment that would become the Wissahickon Formation during a rifting of Rodinia. Sea floor spreading continued until a passive margin developed along the new Iapetus Ocean and a beach strandline developed. These sediments eventually became the Chickies Formation.
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Geology of Pennsylvania
The Geology of Pennsylvania consists of six distinct physiographic provinces, three of which are subdivided into different sections. Each province has its own economic advantages and geologic hazards and plays an important role in shaping everyday life in the state. From the southeast corner to the northwest corner of the state, they include: the Atlantic Plain Province, the Piedmont Province, the New England Province, the Ridge and Valley Province, the Appalachian Province, and the Central Lowlands Province.
A majority of the rocks in Pennsylvania exposed at the surface are sedimentary and were deposited during the Paleozoic Era. Almost all of the metamorphic and igneous rocks are confined to the southeast portion of the state. A total of four orogenies have affected the rocks of the Commonwealth including the Grenville orogeny, the Taconic orogeny, the Acadian orogeny, and the Appalachian orogeny. The Appalachian event has left the most evidence and has continued to shape the landscape of the state. The Pennsylvania terrain has also been affected by continental rifting during the Mesozoic era.
Pleistocene glaciers have also repeatedly visited the state over the last 100,000 years. These glaciers have left some evidence and carved out much of the landscape of the northern tier of the state.
A rock with high economic value from Pennsylvania is anthracite coal. Before mining began, there was an estimated 22.8 billion tons of anthracite in Pennsylvania. In 2001, 12 billion tons still remained in the ground, most of which was not economically feasible to mine. American geologists recognized the importance of Pennsylvania's coal region and named the Upper Carboniferous Period the Pennsylvanian Period because of the abundance of coal in the state. Despite this, Celestine was proposed as the state mineral in 2002. The proposal however, was not approved by the state legislature.
Pennsylvania is also home to the famous Drake Oil Well in Titusville which helped give rise to the modern oil industry and two brand name motor oils, Quaker State (now owned by Royal Dutch Shell) and Pennzoil. Pennsylvania also has reserves of natural gas from both deeply buried source rocks and coal-bed areas.
One of the smallest physiographic provinces in the state is confined to Philadelphia, Delaware, and Bucks counties along the Delaware River. Local relief is less than 200 feet (61 m) and much of the bedrock is buried under recent alluvial deposits. On the geologic map, "Trenton Gravel" is used to describe most of these sediments. Much of the alluvial sediments that exist here are sand, silt, and clays. The traditional boundary of the coastal plain is the Fall Line. The coastal plain in Pennsylvania was once home to thousands of acres of fresh water tidal marsh. This was important in the early development of Philadelphia and Chester. Many of the small tributaries to the Delaware have cut small but impressive gorges into the bedrock, including the Ridley Creek, the Chester Creek, and the Wissahickon Creek. Flash floods are becoming a local problem in the province.
The Piedmont in Pennsylvania is divided into three distinct sections: the Piedmont Uplands, the Piedmont Lowlands, and the Gettysburg-Newark Lowlands. Much of the Piedmont is becoming urbanized and developed. Some of the best farmland in the state is in this region, specifically Lancaster and Chester counties.
This section is characterized by the metamorphic rocks that provide much of the bedrock for this area. The oldest exposed rocks in Pennsylvania are found here and consist of the Baltimore Gneiss. These rocks have a complex history and a vast array of different minerals. They are similar in many respects to their cousins in northern and central Maryland, immediately to the south. Much of the rock was altered during the formation of Rodinia during the Grenville orogeny. These rocks eventually provided the platform for the deposition of sediment that would become the Wissahickon Formation during a rifting of Rodinia. Sea floor spreading continued until a passive margin developed along the new Iapetus Ocean and a beach strandline developed. These sediments eventually became the Chickies Formation.
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