Big South Fork National River and Recreation Area
Encyclopedia
The Big South Fork National River and Recreation Area preserves the Big South Fork of the Cumberland River
and its tributaries in northeastern Tennessee
and southeastern Kentucky
. In addition, the former mining
community of Blue Heron
is preserved and interpreted via signage.
The Big South Fork region contains one of the highest concentrations of natural bridges in the eastern United States and the area is located in parts of Scott, Fentress, Pickett, and Morgan counties in Tennessee, and McCreary County
in Kentucky.
. Water is the most influential agent of geologic change in the Big South Fork region. Over time water action has left many unique and amazing geologic features ranging from the river gorge with its magnificent bluffs to the natural arch
es and unusual hoodoos.
Due to the substantial amount of annual rainfall of the region and the action of the Cumberland River
and surrounding tributaries the water acts to erode the softer Mississippian rock composed of limestone
, shale
, and calcareous sandstone
from beneath the much harder and erosion resistant capstone composed of Pennsylvanian sandstone. Flowing water hollows out the softer layers beneath and forms waterfalls and gorges. Where there is hard capstone intact, arches can form creating natural bridges across streams or a dry ravines. Direct erosion widens a joint and forms a cavity below the more resilient rock thus creating a void between the hard capstone and the area below. As result, water eroded arches are formed in the Big South Fork. Hoodoos
are a rare but intriguing feature occurring in the Big South Fork. These hoodoos form in a similar manner to those found in the western United States. Where tough capstone still exists on the side of a hill for instance, it prevents the erosion of the softer material below. The result is a naturally formed erect columnar rock where once was located a hill.
Big South Fork of the Cumberland River
The Big South Fork of the Cumberland River is a river in Tennessee and Kentucky. It is a major drainage feature of the Cumberland Plateau, a major tributary of the Cumberland River system, a world-class whitewater canoeing and kayaking stream, and the major feature of the Big South Fork National...
and its tributaries in northeastern Tennessee
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...
and southeastern Kentucky
Kentucky
The Commonwealth of Kentucky is a state located in the East Central United States of America. As classified by the United States Census Bureau, Kentucky is a Southern state, more specifically in the East South Central region. Kentucky is one of four U.S. states constituted as a commonwealth...
. In addition, the former mining
Coal mining
The goal of coal mining is to obtain coal from the ground. Coal is valued for its energy content, and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore and for cement production. In the United States,...
community of Blue Heron
Blue Heron, Kentucky
Blue Heron, also known as Mine 18, is a former coal mining community on the banks of the Big South Fork of the Cumberland River in McCreary County, Kentucky, that has been recreated and is maintained as an interpretive history area in the Big South Fork National River and Recreation Area.Blue...
is preserved and interpreted via signage.
The Big South Fork region contains one of the highest concentrations of natural bridges in the eastern United States and the area is located in parts of Scott, Fentress, Pickett, and Morgan counties in Tennessee, and McCreary County
McCreary County, Kentucky
McCreary County is a county located in the U.S. state of Kentucky. As of 2000, the population was 17,080. Its county seat is Whitley City. The county is named for James B. McCreary, a Confederate war hero and Governor of Kentucky from 1875 to 1879. It is the only Kentucky county to not have a...
in Kentucky.
Geology
The Big South Fork’s most prominent feature is the river gorge cutting through the softer Mississippian age rock beneath the hard Pennsylvanian capstone of the Cumberland PlateauCumberland 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...
. Water is the most influential agent of geologic change in the Big South Fork region. Over time water action has left many unique and amazing geologic features ranging from the river gorge with its magnificent bluffs to the natural arch
Natural arch
A natural arch or natural bridge is a natural geological formation where a rock arch forms, with an opening underneath. Most natural arches form as a narrow ridge, walled by cliffs, become narrower from erosion, with a softer rock stratum under the cliff-forming stratum gradually eroding out until...
es and unusual hoodoos.
Due to the substantial amount of annual rainfall of the region and the action of the 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...
and surrounding tributaries the water acts to erode the softer Mississippian rock composed of 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....
, 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 calcareous 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,...
from beneath the much harder and erosion resistant capstone composed of Pennsylvanian sandstone. Flowing water hollows out the softer layers beneath and forms waterfalls and gorges. Where there is hard capstone intact, arches can form creating natural bridges across streams or a dry ravines. Direct erosion widens a joint and forms a cavity below the more resilient rock thus creating a void between the hard capstone and the area below. As result, water eroded arches are formed in the Big South Fork. Hoodoos
Hoodoo (geology)
A hoodoo is a tall, thin spire of rock that protrudes from the bottom of an arid drainage basin or badland. Hoodoos consist of relatively soft rock topped by harder, less easily eroded stone that protects each column from the elements...
are a rare but intriguing feature occurring in the Big South Fork. These hoodoos form in a similar manner to those found in the western United States. Where tough capstone still exists on the side of a hill for instance, it prevents the erosion of the softer material below. The result is a naturally formed erect columnar rock where once was located a hill.