Geology of West Virginia
Encyclopedia
Prior to one billion years ago, the geologic history of West Virginia is obscure. The oldest evidences of life found in West Virginia occur in rocks about 600 million years old, in the Antietam Formation of Lower Cambrian age. The oldest exposed rock, the Catoctin
greenstone
, began to form between about 1,100 and 800 million years ago. Lava
was deposited in the extreme eastern part of the State. About 300 million years later, by the end of Cambrian
time, a shallow sea covered essentially all of West Virginia. Marine deposition took place throughout most of this and the succeeding Ordovician Period. The Taconic orogeny
near the end of Ordovician
time formed a high mountainous area east of West Virginia. Near the end of Devonian
time, the sea was rapidly retreating westward and the continental red beds of the Hampshire Formation were being deposited over most of the State. Approximately 330 million years ago, resulting in the deposition of the Greenbrier Formation, predominantly limestone
, the last marine deposit of significance in the State. Roughly 270 to 225 million years ago, the Appalachian Orogeny began. This orogeny
played a major part in the formation of the Appalachian Mountains
as we know them today. West Virginia was uplifted, important deposition of sediments ceased, and erosion began taking place. About 310 million years ago, West Virginia was essentially a land area, subject to erosion
. Swamp
conditions prevailed more than 50 million years , resulting in the deposition of thousands of feet of nonmarine sandstone
and shale
and the many important coal
seams that we know today.
was deposited in the extreme eastern part of the State forming our oldest exposed rock, the Catoctin greenstone. Later, perhaps about 800 million years ago, a narrow trough began to form in extreme eastern West Virginia. An arm of the sea entered and sediment
s accumulated. As time went on, this shallow sea
transgressed westward. By the end of Cambrian
time, about 300 million years later, this shallow sea covered essentially all of West Virginia. Marine deposition took place throughout most of this and the succeeding Ordovician Period. During this total interval of about 370 million years, most of the rocks
exposed in Jefferson and eastern Berkeley counties and in scattered areas southwestward along the Virginia
boundary were deposited. Rocks of the same age are found in abundance in the deep wells throughout the State.
The Taconic orogeny
near the end of Ordovician
time formed a high mountainous area east of West Virginia. These highlands formed the main source of sediments for the succeeding Silurian Period and part of the Devonian Period. Both clastics and carbonate
s were deposited in a mixed marine and nonmarine environment, with clastics predominating in the eastern part of the State. Evaporite
s were deposited in northern West Virginia in Late Silurian time.
During Middle and Late Devonian time the Acadian Orogeny
, with the main uplift to the northeast, resulted in a further source for the predominantly clastic marine deposits of these epochs. However, near the end of Devonian
time, the sea was rapidly retreating westward and the continental red beds of the Hampshire Formation were being deposited over most of the State.
The sea made one more important intrusion into West Virginia during Middle Mississippian time, approximately 330 million years ago, resulting in the deposition of the Greenbrier Formation, predominantly limestone
, the last marine deposit of significance in the State.
At the close of Mississippian time, about 310 million years ago, West Virginia was essentially a land area, subject to erosion
. Early in the succeeding Pennsylvanian Period, the area dropped to near sea level and for more than 50 million years continued to sink at about the same rate that deposition was taking place. Only occasionally and for very short periods of time did the area fall below sea level. Swamp
conditions prevailed, resulting in the deposition of thousands of feet of nonmarine sandstone
and shale
and the many important coal
seams that we know today.
During the Permian Period, roughly 270 to 225 million years ago, the Appalachian Orogeny began. West Virginia was uplifted, important deposition of sediments ceased, and erosion began taking place. Much folding and thrust faulting occurred, especially in the eastern part of the State. This orogeny
played a major part in the formation of the Appalachian Mountains
as we know them today. Never again has the sea invaded West Virginia.
No sedimentary rocks from the Mesozoic Era, which extended from 225 to 66 million years ago, are present in West Virginia. In other parts of world rocks of this age contain the remains of countless species of dinosaur
s and other reptiles; unfortunately, no such fossil
s are preserved in our State. During the early part of the era, considerable igneous activity took place in neighboring states to the east. A few dikes of gabbro
and other mafic rock from the Jurassic Period, 210 to 145 million years ago, are present in Pendleton and surrounding counties.
In the Cenozoic Era, which extended from 65 million years ago to present day, igneous activity was renewed in the eastern part of the State. Approximately 45 million years ago, a complex of dikes and sills with compositions ranging from basalt to rhyolite were intruded into the Paleozoic sedimentary rocks in the area in and around Pendleton County. These unusual igneous rocks are some of the youngest in eastern North America. Late in the Cenozoic Era, in fact extending to less than 100,000 years ago, glaciers covered the northern part of the North American continent, extending almost to the Northern Panhandle of West Virginia, but not into the State. Prior to the advance of these ice sheets, drainage of the Monongahela River was northward to the St. Lawrence River system. The ice sheet caused damming and a lake extended as far south as Weston. Important lake deposits, predominantly clay
, were thus laid down in the Monongahela River basin. Drainage was diverted westward into the Ohio River system. Divergence of the New River system that formerly drained northwestward caused the deposition of similar deposits in the old Teays River channel between Charleston and Huntington. Except for recent alluvial deposits, there are no other known Cenozoic rocks.
The oldest evidences of life found in West Virginia occur in rocks about 600 million years old, in the Antietam Formation of Lower Cambrian age. However, in this formation they are abundant and of forms that had already developed through a substantial part of all evolution that has taken place during the history of the earth. Evidences of life in other parts of the earth are found in rocks at least 3 billion years old. Fossil
s are found in increasing abundance and increasing stages of evolution
al development in the rocks of all ages since earliest Cambrian
time.
Article provided by the 'West Virginia Geological and Economic Survey.' (adapted from an educational booklet by Dudley Cardwell, 1975 with additions from Ron McDowell, 2007)
Catoctin Mountain
Catoctin Mountain, along with the geologically associated Bull Run Mountains, comprises the easternmost mountain ridge of the Blue Ridge Mountains, which are in turn a part of the Appalachian Mountains range...
greenstone
Greenschist
Greenschist is a general field petrologic term applied to metamorphic or altered mafic volcanic rock. The term greenstone is sometimes used to refer to greenschist but can refer to other rock types too. The green is due to abundant green chlorite, actinolite and epidote minerals that dominate the...
, began to form between about 1,100 and 800 million years ago. Lava
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...
was deposited in the extreme eastern part of the State. About 300 million years later, by the end of Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
time, a shallow sea covered essentially all of West Virginia. Marine deposition took place throughout most of this and the succeeding Ordovician Period. The Taconic orogeny
Taconic orogeny
The Taconic orogeny was a mountain building period that ended 440 million years ago and affected most of modern-day New England. A great mountain chain formed from eastern Canada down through what is now the Piedmont of the East coast of the United States...
near the end of 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...
time formed a high mountainous area east of West Virginia. Near the end of Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
time, the sea was rapidly retreating westward and the continental red beds of the Hampshire Formation were being deposited over most of the State. Approximately 330 million years ago, resulting in the deposition of the Greenbrier Formation, predominantly limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
, the last marine deposit of significance in the State. Roughly 270 to 225 million years ago, the Appalachian Orogeny began. This orogeny
Orogeny
Orogeny refers to forces and events leading to a severe structural deformation of the Earth's crust due to the engagement of tectonic plates. Response to such engagement results in the formation of long tracts of highly deformed rock called orogens or orogenic belts...
played a major part in the formation of the Appalachian Mountains
Appalachian Mountains
The Appalachian Mountains #Whether the stressed vowel is or ,#Whether the "ch" is pronounced as a fricative or an affricate , and#Whether the final vowel is the monophthong or the diphthong .), often called the Appalachians, are a system of mountains in eastern North America. The Appalachians...
as we know them today. West Virginia was uplifted, important deposition of sediments ceased, and erosion began taking place. About 310 million years ago, West Virginia was essentially a land area, subject to erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
. Swamp
Swamp
A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or swamp...
conditions prevailed more than 50 million years , resulting in the deposition of thousands of feet of nonmarine 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,...
and shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
and the many important coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
seams that we know today.
History
Prior to one billion years ago, the geologic history of West Virginia is obscure. Sometime between about 1,100 and 800 million years ago, lavaLava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...
was deposited in the extreme eastern part of the State forming our oldest exposed rock, the Catoctin greenstone. Later, perhaps about 800 million years ago, a narrow trough began to form in extreme eastern West Virginia. An arm of the sea entered and sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
s accumulated. As time went on, this shallow sea
Sea
A sea generally refers to a large body of salt water, but the term is used in other contexts as well. Most commonly, it means a large expanse of saline water connected with an ocean, and is commonly used as a synonym for ocean...
transgressed westward. By the end of Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
time, about 300 million years later, this shallow sea covered essentially all of West Virginia. Marine deposition took place throughout most of this and the succeeding Ordovician Period. During this total interval of about 370 million years, most of the rocks
Rock (geology)
In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
exposed in Jefferson and eastern Berkeley counties and in scattered areas southwestward along the Virginia
Virginia
The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...
boundary were deposited. Rocks of the same age are found in abundance in the deep wells throughout the State.
The Taconic orogeny
Taconic orogeny
The Taconic orogeny was a mountain building period that ended 440 million years ago and affected most of modern-day New England. A great mountain chain formed from eastern Canada down through what is now the Piedmont of the East coast of the United States...
near the end of 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...
time formed a high mountainous area east of West Virginia. These highlands formed the main source of sediments for the succeeding Silurian Period and part of the Devonian Period. Both clastics and carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
s were deposited in a mixed marine and nonmarine environment, with clastics predominating in the eastern part of the State. Evaporite
Evaporite
Evaporite is a name for a water-soluble mineral sediment that result from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporate deposits, marine which can also be described as ocean deposits, and non-marine which are found in standing bodies of...
s were deposited in northern West Virginia in Late Silurian time.
During Middle and Late Devonian time the Acadian Orogeny
Acadian orogeny
The Taconic, Acadian and Alleghenian orogenies are the three tectonic phases responsible for the formation of the present Appalachian Mountains. The Acadian orogeny is a middle Paleozoic mountain building episode dating back 325-400 million years which should not be regarded as a single event but...
, with the main uplift to the northeast, resulted in a further source for the predominantly clastic marine deposits of these epochs. However, near the end of Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
time, the sea was rapidly retreating westward and the continental red beds of the Hampshire Formation were being deposited over most of the State.
The sea made one more important intrusion into West Virginia during Middle Mississippian time, approximately 330 million years ago, resulting in the deposition of the Greenbrier Formation, predominantly limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
, the last marine deposit of significance in the State.
At the close of Mississippian time, about 310 million years ago, West Virginia was essentially a land area, subject to erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
. Early in the succeeding Pennsylvanian Period, the area dropped to near sea level and for more than 50 million years continued to sink at about the same rate that deposition was taking place. Only occasionally and for very short periods of time did the area fall below sea level. Swamp
Swamp
A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or swamp...
conditions prevailed, resulting in the deposition of thousands of feet of nonmarine 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,...
and shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
and the many important coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
seams that we know today.
During the Permian Period, roughly 270 to 225 million years ago, the Appalachian Orogeny began. West Virginia was uplifted, important deposition of sediments ceased, and erosion began taking place. Much folding and thrust faulting occurred, especially in the eastern part of the State. This orogeny
Orogeny
Orogeny refers to forces and events leading to a severe structural deformation of the Earth's crust due to the engagement of tectonic plates. Response to such engagement results in the formation of long tracts of highly deformed rock called orogens or orogenic belts...
played a major part in the formation of the Appalachian Mountains
Appalachian Mountains
The Appalachian Mountains #Whether the stressed vowel is or ,#Whether the "ch" is pronounced as a fricative or an affricate , and#Whether the final vowel is the monophthong or the diphthong .), often called the Appalachians, are a system of mountains in eastern North America. The Appalachians...
as we know them today. Never again has the sea invaded West Virginia.
No sedimentary rocks from the Mesozoic Era, which extended from 225 to 66 million years ago, are present in West Virginia. In other parts of world rocks of this age contain the remains of countless species of dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s and other reptiles; unfortunately, no such fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s are preserved in our State. During the early part of the era, considerable igneous activity took place in neighboring states to the east. A few dikes of gabbro
Gabbro
Gabbro refers to a large group of dark, coarse-grained, intrusive mafic igneous rocks chemically equivalent to basalt. The rocks are plutonic, formed when molten magma is trapped beneath the Earth's surface and cools into a crystalline mass....
and other mafic rock from the Jurassic Period, 210 to 145 million years ago, are present in Pendleton and surrounding counties.
In the Cenozoic Era, which extended from 65 million years ago to present day, igneous activity was renewed in the eastern part of the State. Approximately 45 million years ago, a complex of dikes and sills with compositions ranging from basalt to rhyolite were intruded into the Paleozoic sedimentary rocks in the area in and around Pendleton County. These unusual igneous rocks are some of the youngest in eastern North America. Late in the Cenozoic Era, in fact extending to less than 100,000 years ago, glaciers covered the northern part of the North American continent, extending almost to the Northern Panhandle of West Virginia, but not into the State. Prior to the advance of these ice sheets, drainage of the Monongahela River was northward to the St. Lawrence River system. The ice sheet caused damming and a lake extended as far south as Weston. Important lake deposits, predominantly clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
, were thus laid down in the Monongahela River basin. Drainage was diverted westward into the Ohio River system. Divergence of the New River system that formerly drained northwestward caused the deposition of similar deposits in the old Teays River channel between Charleston and Huntington. Except for recent alluvial deposits, there are no other known Cenozoic rocks.
The oldest evidences of life found in West Virginia occur in rocks about 600 million years old, in the Antietam Formation of Lower Cambrian age. However, in this formation they are abundant and of forms that had already developed through a substantial part of all evolution that has taken place during the history of the earth. Evidences of life in other parts of the earth are found in rocks at least 3 billion years old. Fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s are found in increasing abundance and increasing stages of evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
al development in the rocks of all ages since earliest Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
time.
Article provided by the 'West Virginia Geological and Economic Survey.' (adapted from an educational booklet by Dudley Cardwell, 1975 with additions from Ron McDowell, 2007)