Geology of Tennessee
Encyclopedia
The geology of Tennessee
is as diverse as its landscapes. Politically, Tennessee is broken up into three Grand Divisions
: East
, Middle
, and West Tennessee
. Physically, Tennessee is also separated into three main types of landforms: river valley plain, highlands and basins, and mountains.
to the Mississippian
, roughly between 400 and 300 million years ago. The sediment was primarily deep ocean limestone
s with some shale
layers. Mississippian limestones are generally thicker than those of the Ordovician, and additionally, more chert
y. In the Ordovician, the Appalachian Mountains
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
today.
. The famous Coon Creek Formation
is one of these, lay down as a sandy shoreline during the Cretaceous
. Many large sea creatures, including mesosaur
s and plesiosaur
s as well as ammonite
s ruled the seas that covered the area. Because this area was underwater at this time, there are no land dinosaur
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.
By the Cenozoic, the sea level had dropped to its current level and the North American continent dried out. The Mississippi River
as well as the Tennessee and Cumberland River
s formed and cut deep into the valleys. The Nashville Basin
, which in reality is a geologic dome
, was pushed up from underneath by a mantle plume, 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
as sands and silts.
Tennessee
Tennessee is a U.S. state located in the Southeastern United States. It has a population of 6,346,105, making it the nation's 17th-largest state by population, and covers , making it the 36th-largest by total land area...
is as diverse as its landscapes. Politically, Tennessee is broken up into three Grand Divisions
Grand Divisions (Tennessee)
The Grand Divisions are geographic, cultural, and legally recognized regions, each constituting roughly one-third of the State of Tennessee. The Grand Divisions are represented prominently by the three stars on the flag of Tennessee...
: East
East Tennessee
East Tennessee is a name given to approximately the eastern third of the U.S. state of Tennessee, one of the three Grand Divisions of Tennessee defined in state law. East Tennessee consists of 33 counties, 30 located within the Eastern Time Zone and three counties in the Central Time Zone, namely...
, Middle
Middle Tennessee
Middle Tennessee is a distinct portion of the state of Tennessee, delineated according to state law as the 41 counties in the Middle Grand Division of Tennessee....
, and West Tennessee
West Tennessee
West Tennessee is one of the three Grand Divisions of the State of Tennessee. Of the three, it is the one that is most sharply defined geographically. Its boundaries are the Mississippi River on the west and the Tennessee River on the east...
. 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 OrdovicianOrdovician
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...
to the Mississippian
Mississippian (geologic period)
The Mississippian is a subperiod in the geologic timescale or a subsystem of the geologic record. It is the earliest/lowermost of two subperiods of the Carboniferous period lasting from roughly 359 to 318 Ma...
, roughly between 400 and 300 million years ago. The sediment was primarily deep ocean 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....
s with some 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...
layers. Mississippian limestones are generally thicker than those of the Ordovician, and additionally, more chert
Chert
Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color , but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements...
y. In the Ordovician, 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...
began to form and by the end of the Paleozoic were tall peaks. During the Pennsylvanian
Pennsylvanian
The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly . As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain...
, the Cumberland Plateau
Cumberland Plateau
The Cumberland Plateau is the southern part of the Appalachian Plateau. It includes much of eastern Kentucky and western West Virginia, part of Tennessee, and a small portion of northern Alabama and northwest Georgia . The terms "Allegheny Plateau" and the "Cumberland Plateau" both refer to the...
formed along the edge of the Appalachians as beach and shore sediments, primarily 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,...
today.
The Mesozoic
Most Mesozoic sediments were deposited in West Tennessee, along the present course of the Tennessee RiverTennessee River
The Tennessee River is the largest tributary of the Ohio River. It is approximately 652 miles 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 names...
. The famous Coon Creek Formation
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 in age, about 70 million years old. The formation is known for producing mosasaurs and plesiosaurs, particularly at Coon Creek in...
is one of these, lay down as a sandy shoreline during the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
. Many large sea creatures, including mesosaur
Mesosaur
Mesosaurs were a group of small aquatic reptiles that lived during the early Permian period, roughly 299 to 270 million years ago. Mesosaurs were the first aquatic reptiles, having apparently returned to an aquatic lifestyle from more terrestrial ancestors...
s and plesiosaur
Plesiosaur
Plesiosauroidea is an extinct clade of carnivorous plesiosaur marine reptiles. Plesiosauroids, are known from the Jurassic and Cretaceous Periods...
s as well as ammonite
Ammonite
Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct subclass within the Molluscan class Cephalopoda which are more closely related to living coleoids Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct...
s ruled the seas that covered the area. Because this area was underwater at this time, there are no land 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 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
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
as well as the Tennessee and Cumberland River
Cumberland River
The Cumberland River is a waterway in the Southern United States. It is long. It starts in Harlan County in far southeastern Kentucky between Pine and Cumberland mountains, flows through southern Kentucky, crosses into northern Tennessee, and then curves back up into western Kentucky before...
s formed and cut deep into the valleys. The Nashville Basin
Nashville Basin
The Nashville Basin, also known as the Central Basin, is a term often used to describe the area surrounding Nashville, Tennessee. The Central Basin was caused by an uplifting known as the Nashville Dome. The Nashville Dome is evidenced by the underlying rock strata that all dip downwards away from...
, which in reality is a geologic dome
Dome (geology)
In structural geology, a dome is a deformational feature consisting of symmetrically-dipping anticlines; their general outline on a geologic map is circular or oval...
, was pushed up from underneath by a mantle plume, exposing softer strata that with additional erosion on the Highland Rim
Highland Rim
The Highland Rim is a geographic term for the area in Tennessee surrounding the Central Basin. Nashville is largely surrounded by higher terrain in all directions....
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
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 confluence with the Ohio River at Cairo, Illinois. The embayment...
as sands and silts.
Geological formations of Tennessee
- CretaceousCretaceousThe Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
- Coon Creek FormationCoon Creek FormationThe Coon Creek Formation is a geologic formation located in western Tennessee and extreme northeast Mississippi. It is a sedimentary sandy marl deposit, Late Cretaceous in age, about 70 million years old. The formation is known for producing mosasaurs and plesiosaurs, particularly at Coon Creek in...
- Coon Creek Formation
- PennsylvanianPennsylvanianThe Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly . As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain...
- See Cumberland PlateauCumberland PlateauThe Cumberland Plateau is the southern part of the Appalachian Plateau. It includes much of eastern Kentucky and western West Virginia, part of Tennessee, and a small portion of northern Alabama and northwest Georgia . The terms "Allegheny Plateau" and the "Cumberland Plateau" both refer to the...
- See Cumberland Plateau
- MississippianMississippian (geologic period)The Mississippian is a subperiod in the geologic timescale or a subsystem of the geologic record. It is the earliest/lowermost of two subperiods of the Carboniferous period lasting from roughly 359 to 318 Ma...
- Ste. Genevieve LimestoneSte. Genevieve LimestoneThe Ste. Genevieve Limestone is a geologic formation named for Ste. Genevieve, Missouri where it is exposed and was first described. It is a thick-bedded limestone that overlies the St. Louis Limestone. Both are Mississippian in age and part of the Meramecian series.Members of the Ste...
- St. Louis LimestoneSt. Louis LimestoneThe St. Louis Limestone is a large geologic formation covering a wide area of the midwest of the United States. It is named after an exposure at St. Louis, Missouri. It consists of sedimentary limestone with scattered chert beds, including the heavily chertified Lost River Chert Bed in the Horse...
- Warsaw Formation
- Fort Payne FormationFort Payne FormationThe Fort Payne Formation, or Fort Payne Chert, is a geologic formation found in the southeastern region of the United States. It is a Mississippian cherty limestone that overlies the Chattanooga Shale and underlies the St. Louis Limestone . To the north, it grades into the siltstone Borden Formation...
- Ste. Genevieve Limestone
- DevonianDevonianThe 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...
- Chattanooga Shale
- SilurianSilurianThe Silurian is a geologic period and system that extends from the end of the Ordovician Period, about 443.7 ± 1.5 Mya , to the beginning of the Devonian Period, about 416.0 ± 2.8 Mya . As with other geologic periods, the rock beds that define the period's start and end are well identified, but the...
- OrdovicianOrdovicianThe 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...
- 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