The geology of

Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to th ...

is as diverse as its landscapes. Politically, Tennessee is broken up into three Grand Divisions:

East East or Orient is one of the four cardinal directions or points of the compass. It is the opposite direction from west and is the direction from which the Sun rises on the Earth. Etymology As in other languages, the word is formed from the fac ...

, Middle, and

West Tennessee West Tennessee is one of the three Grand Divisions of the U.S. state of Tennessee that roughly comprises the western quarter of the state. The region includes 21 counties between the Tennessee and Mississippi rivers, delineated by state law. Its ...

. Physically, Tennessee is also separated into three main types of landforms: river valley plain, highlands and basins, and mountains.

The Paleozoic

Most of the sediment across Middle Tennessee was deposited from the

Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. T ...

to the Mississippian, roughly between 400 and 300 million years ago. The sediment was primarily deep ocean

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

s with some shale layers. Mississippian limestones are generally thicker than those of the Ordovician, and additionally, more

chert Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a ...

y. In the Ordovician, the

Appalachian Mountains The Appalachian Mountains, often called the Appalachians, (french: Appalaches), are a system of mountains in eastern to northeastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. They ...

began to form and by the end of the Paleozoic were tall peaks. During the Pennsylvanian, the Cumberland Plateau formed along the edge of the Appalachians as beach and shore sediments, primarily

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

today.

The Mesozoic

Most Mesozoic sediments were deposited in West Tennessee, along the present course of the

Tennessee River The Tennessee River is the largest tributary of the Ohio River. It is approximately long and is located in the southeastern United States in the Tennessee Valley. The river was once popularly known as the Cherokee River, among other name ...

. The

Coon Creek Formation The Coon Creek Formation is a geologic formation located in western Tennessee and extreme northeast Mississippi. It is a sedimentary sandy marl deposit, Late Cretaceous (Maastrichtian) in age, about 70 million years old. The formation is known for ...

is one of these, deposited as a sandy shoreline along the

Mississippi Embayment The Mississippi embayment is a physiographic feature in the south-central United States, part of the Mississippi Alluvial Plain. It is essentially a northward continuation of the fluvial sediments of the Mississippi River Delta to its conflue ...

during the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

. Many large sea creatures, including

mosasaur Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Greek ' meaning 'lizard') comprise a group of extinct, large marine reptiles from the Late Cretaceous. Their first fossil remains were discovered in a limestone quarry at Maastricht on ...

s and plesiosaurs as well as ammonites ruled the seas that covered the area. Because this area was underwater at this time, there are no land

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

s in the fossil record. The Appalachians to the east also experienced erosion at this time and were smoothed down to near their current elevation.

The Cenozoic

By the Cenozoic, the sea level had dropped to its current level and the North American continent dried out. The

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it fl ...

as well as the Tennessee and Cumberland Rivers formed and cut deep into the valleys. The

Nashville Basin The Nashville Basin, also known as the Central Basin, is a term often used to describe the area surrounding Murfreesboro, Tennessee, in which Nashville is located. The Central Basin was caused by an uplifting which produced a dome known as the N ...

, which in reality is a geologic dome, was pushed up from underneath by a

mantle plume A mantle plume is a proposed mechanism of convection within the Earth's mantle, hypothesized to explain anomalous volcanism. Because the plume head partially melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hot ...

, exposing softer strata that with additional erosion on the Highland Rim surrounding the basin expanded the size of the basin. The basin is likely to continue widening far into the future. Most Cenozoic deposits occur in West Tennessee near the

Mississippi embayment The Mississippi embayment is a physiographic feature in the south-central United States, part of the Mississippi Alluvial Plain. It is essentially a northward continuation of the fluvial sediments of the Mississippi River Delta to its conflue ...

as sands and silts.

Geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...
s of Tennessee

* Pennsylvanian **See Cumberland Plateau ** Crooked Fork Group, including Wartburg Sandstone, Glenmary Shale, Coalfield Sandstone, Burnt Mill Shale, Crossville Sandstone, Dorton Shale ** Crab Orchard Mountains Group, including Rockcastle Conglomerate, Vandever Formation, Newton Sandstone, Whitwell Shale, and Sewanee Conglomerate ** Gizzard Group, including Signal Point Shale, Warren Point Sandstone, and Raccoon Mountain Formation * Mississippian **

Pennington Formation The Pennington Formation is a geologic formation named for Pennington Gap, Virginia.Butts, Charles. Geology and Oil Possibilities of the Northern Part of Overton County, Tenn., and of Adjoining Parts of Clay, Pickett and Fentress Counties', pp. 2 ...

** Bangor Limestone ** Hartselle Sandstone ** Ste. Genevieve Limestone ** St. Louis Limestone **

Warsaw Formation The Warsaw Formation is a geologic formation in Illinois, Iowa and Missouri. It preserves fossils dating back to the Mississippian subperiod. See also * List of fossiliferous stratigraphic units in Illinois * List of fossiliferous stratigraph ...

Fort Payne Formation The Fort Payne Formation, or Fort Payne Chert, is a geologic formation found in the southeastern region of the United States. It is a Mississippian Period cherty limestone, that overlies the Chattanooga Shale (or locally the Maury Formation), a ...

* Devonian **

Chattanooga Shale The Chattanooga Shale is a geologic formation in Alabama, Arkansas, Kentucky, Missouri and Tennessee. It preserves conodont fossils dating to the Devonian Period. It occurs mostly as a subsurface geologic formation composed of layers of shale. It ...

* Silurian *

** Richmond Group (geologic feature) ** Lebanon Limestone ** Ridley Limestone ** Bigby-Cannon Limestone ** Leipers Formation ** Catheys Formation ** Pegram Formation ** Hermitage Formation ** Laurel Limestone ** Murfreesboro Limestone ** Pierce Limestone

External links

Landforms of Tennessee
{{Geology of the United States by political division

Natural history of Tennessee

The Paleozoic

The Mesozoic

The Cenozoic

Geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...s of Tennessee

See also

External links

Geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...
s of Tennessee