The document discusses the karst formations of the Cumberland Plateau in East Tennessee. It describes the geology and formation of the plateau over millions of years, including the different rock layers that were deposited under sea and subjected to lithification. Subterranean streams have eroded and shaped caves in the plateau by dissolving limestone and transporting sediment. The streams flow horizontally through bedding planes and joints until exiting the escarpment onto a sinkhole plain, continuing to shape the landscape over hundreds of millions of years.

1. Aubree Duncan
11275124
Sherman- GY 363
Term Paper
December 04, 2014
Karst Formations of the Cumberland Plateau in East Tennessee
ABSTRACT:
This research focuses on the region of the Cumberland Plateau located in Eastern
Tennessee. It includes what the Cumberland Plateau is, how it was created, and the lithology of
the landform. This research goes into detail about the influence of the different geologic layers of
the plateau on the subterranean stream systems of the region. The different cave models within
the Cumberland Plateau are also a focus in the research. The Cumberland Plateau has
transformed for millions of years. The purpose of this research is to understand and explain what
processes have created and changed the landform. Ultimately, this research is in hopes to be able
to interpret the ongoing and historic change of the region.
INTRODUCTION:
Being a Tennessee native, I have been lucky enough to grow up surrounded by beautiful
landscapes. The rolling hills and mountains of East Tennessee are breathtaking but I have always
been interested in what is underground. Tennessee is part of the TAG region, “Tennessee-
Alabama-Georgia.” These three states are comprised of layers of limestone that formed millions
of years ago, leaving the landscape susceptible to acid erosion. This creates an intricate
subterranean world of caves, tunnels, and underground water systems.
In the TAG region, there are more than 14,000 known caves; 9,200 of these caves are in
Tennessee. I spent this past summer as an intern at Fall Creek Calls State Park located in
Pikeville, Tennessee at the eastern edge of the Cumberland Plateau. While there, one of my jobs

2. was to give cave tours of Lost Creek Cave; which sparked my love for the subterranean world
even more.
DISCUSSION:
The Cumberland Plateau itself extends southwest 450 miles from southern West Virginia
into Northern Alabama. Its’ width ranges between 40 to 50 miles. The plateau is bounded
between the Appalachian Ridge and Valley to the east and the Eastern Highland Rim to the west.
The landscape can be described as being a rugged upland. This is because of the plateaus aspect.
Compared to the Eastland Highland rim that reaches an elevation of 275-350 m above sea level
(asl), the Cumberland Plateau towers above it at 550-610 m asl (Anthony & Granger 46). This
eastward-retreating escarpment on the west margin of the Cumberland Plateau has been created
by approximately 180 million years of lowering between the sandstone caprock of the
Cumberland Plateau and the limestone surface of the Highland Rim. Figure 1 is a physiographic
map of Tennessee that shows where the Cumberland Plateau is in relation to other physiographic
regions in Tennessee.
Figure 1. Physiographic Map of Tennessee

3. The Cumberland Plateau is an elaborate formation comprised of multiple layers of
million year old rocks. The Caprock of the plateau has four different layers: Sewanee
Conglomerate, Signal Point Shale, Warren Point Sandstone, and the Pennington Formation.
Below the caprock, the retreating escarpment begins. First, is a layer of Bangor Limestone then,
a thin impermeable stratum called the Hartselle Formation. Below the Hartselle Formation is a
layer of Monteagle Limestone which ends the retreating escarpment and begins the Sinkhole
Plain. The sinkhole plain is made up of the bottom three layers of the Cumberland Plateau: St.
Louis Limestone, the Warsaw Formation, and the Fort Payne Formation bedrock. Figure 2 is a
diagram that depicts the layers of the Cumberland Plateau. It also illustrates subterranean stream
invasion and slope retreat along the Cumberland Plateau escarpment of Tennessee.
Figure 2. Subterranean Streat Invasion & Slope Retreat of Cumberland Plateau

4. The present structure of the Cumberland Plateau has resulted from the regional eastward
dip of the Cincinnati arch and the Pine Mountain, Cumberland Plateau, and Sequatchie Valley
bedding thrusts. The Cincinnati arch is the only structural control affecting the undisturbed
portion of the plateau and is the primary structural component in the faulted area (Wilson &
Stearns). However, the bedding thrusts do not affect the position or aspect of the strata that are
within the thrust sheets. Figure 3 shows the topography of Tennessee. The Cumberland Plateau
(outlined) stands out in a green strip, with the Sequatchie Valley in a vertical blue strip cutting
hallway through the middle of the Plateau. A sinkhole plain is visible on each side of the plateau.
Figure 3. Topography of Tennessee
During the Mississippian period, the Cumberland Plateau was part of an ancient sea.
Later in the Pennsylvanian period (318-299 million years ago, mya) the sea deepened. The wave
action wore down the Appalachian Mountains and led to millions of tons of sand being deposited
in the sea. The sediment buried countless underwater forests, as well. The dead organic material
from the organisms that lived in the sea was also buried. This dead organic material and
sediment formed layers that were thousands of feet deep. Eventually, the weight of the
overburden became so immense that lithification began. This process is responsible for the

5. different layers of shale, coal, limestone, and sandstone rock that make up the Cumberland
Plateau.
At the beginning of the Permian period (285-248 mya) the Cumberland Plateau was lifted
over 2000 feet asl (Des Jean). According to plate tectonic theory, the North American plate has
been moving westward since it collided with Northwest Africa in the Early Triassic era. During
the collision, rocks were uplifted and erosion started to shape the landscape as soon as the uplift
event took place. There has not been any orogeny in the region but denudation does occur to the
rocks that were uplifted and deformed during the collision.
For the last 200 million years, weathering and erosion have been main factors in shaping
the landscape. It has been hypothesized that the uplift event caused caprock to be removed from
large areas. This left the Mississippian limestone exposed to the elements. The area that
experiences the greatest amount of caprock removal is the southern Appalachian Plateaus
Province, where the Cumberland Plateau is located (Crawford).
Currently, the Cumberland Plateau caprock is being eroded vertically and horizontally. In
areas where the caprock has been removed, surface streams dissolve the calcium carbonate and
become subsurface streams. Theses streams act in mechanical and chemical weathering as they
incise their way to the escarpment base. The streams carry suspended loads and bed loads that
enlarge the conduits by abrasion. These loads are only partially responsible for the creation of the
karst landscape. Corrosion and corrasion, especially during floods, are the main causes of
enlargement of caves.
It has been concluded that subterranean invasion of caprock streams is directly related to
caprock removal by slope retreat (Crawford). When the caprock is removed, the limestone layers

6. become more vulnerable to invasion and carbonation. The invasion occurs when aggressively
moving water is able to flow through joints and bedding planes as it makes its way to the
escarpment base. The strata do not exclusively control the water flow and the water does not
flow directly down the strata. Jointing mostly controls the flow of the subterranean streams. The
water is able to solutionally enlarge the stream conduit. Then when suspended loads and
bedloads enter the system, corrasion rates increase to further enlarge the cave. All of which,
contribute to the karst landscape of the region.
As mentioned, there are impermeable layers within the layers of limestone that make up
the Cumberland Plateau. These layers cause the subterranean streams to move down the
escarpment in a stair step manner. These impermeable stair steps act as controls for cave
development but do not lead to perched water tables. They only act as a control on the elevation
of the subsurface streams.
Vertical input of water sourced from perched caprock aquifers can too create a cave. This
occurs when joints are opened by the release of pressure near the edge of the escarpment. Caves
that are formed this way are usually smaller in cross-sectional area versus a Cumberland-style
horizontal cave since high discharge and abrasion do not have much influence on its structure.
Subsurface waterfalls can break through impermeable layers and erode vertical shafts to create
dome pits. An example of this would be Rumbling Falls Cave at Fall Creek Falls SP.
The vertical wasting of the plateau surface causes weathered material removed by
streams to descend abruptly from the tabletop of the plateau onto the sinkhole plain. The
weathered limestone that left the escarpment has accumulated as a thick layer of regolith over the
area that follows the retreating escarpment. Some regolith of the sinkhole plain has also been

7. derived from the weathering of the lower Monteagle and St. Louis limestones. Surprisingly,
these rocks contain a relatively high percentage of noncalcerous materials. In some areas of the
sinkhole plain, there are layers of chert that are up to a meter thick. Other areas of the plain
contain sand with thin beds of calcerous shale. Primarily, the material covering the sinkhole plain
is caprock material that has been deposited at the base of the escarpment. There is evidence of
caves in the sinkhole plain that have been caused by short ephemeral streams that flow over the
regolith into swallets. Figure 4 shows the distribution of caves and sinkholes in Tennessee. As
you can see, most caves and sinkholes are distributed at the western edge of the eastern retreating
escarpment of the Cumberland Plateau.
Figure 4. Cave and Sinkholes in TN
The different layers of the Cumberland Plateau are the structural base level control for the
stream caves. When subterranean stream invasion first occurs, it leaves the shale and sandstone
caprock plateau onto the Bangor limestone layer where the overlying shales meet the underlying

8. carbonates. The Bangor limestone has a very high degree of secondary permeability along joints
and bedding planes. This gives way to maximum water movement through more efficient routes.
These streams eventually resurface on top of the impermeable Hartselle formation that is further
down the slope.
Multilevel caves are formed when a stream is forced to lower its bed and downcuts,
which erodes out a new passage. This typically occurs when a subsurface stream reaches an
impermeable layer like the Hartselle formation. Since an impermeable layer remains a control,
resurgence by an invading caprock stream is possible. These streams flow for a short time before
they drop off the formation into a domepit, like Rumbling Falls. These domepits are often times
enlarged joints in the layer below. In the case of the Cumberland Plateau, the streams typically
invade the caprock, become a subsurface stream, flow through the Bangor limestone until it
reaches the impermeable Hartselle formation, and then abruptly descends into a dome pit within
the Monteagle limestone below.
The Cumberland Plateau is not limited to only one method of cave development. In
1984, Crawford first described the “plateau-margin” model for cave development. This model
explained that surface streams undersaturated in calcite were able to cross the sandstone caprock.
These streams would sink where the sandstone and limestone layers met and form caves in the
vadose zone leading to the local water table. Typically, plateau-margin caves are narrow,
vertical canyons that lead down to the modern water table. The overall dimensions of these
passages, surveyed length to cross sectional area, are small. Figure 5 shows a caver descending
down a plateau-margin passage.

9. Speleologists have seen that there are caves within the
Cumberland Plateau that are clearly developed in a hydrologic
setting but, do not have the same characteristics of the plateau-
margin caves. Instead, the caves have large, hydologically
abandoned passages that were thought to have come from
phreatic origin above the modern water table (Anthony &
Granger 47). These caves were named “fossil caves” by Mann
in 1982. The caves get their large shape from recharge of the
plateau combined with back flooding of surface discharge
springs. Mann speculated that these high discharge events
produced extreme hydrostatic pressure in the phreatic conduits.
The high pressure was able to develop the large passages “under pipe-full” conditions (Anthony
& Granger 47).
Sasowsky discovered a model similar to fossil caves in 1992 named “Cumberland-style”
caves. These caves included some
of the same fossil cave features, like
abandoned trunk passages that were
at different levels above the modern
river level. Speleogenesis is the
main difference between these two
cave models. Unlike plateau-
margin, Cumberland-style caves
follow topographic contours that
Figure 5. Plateau-margin Descend
Figure 6. Cumberland-Style Cave (Cumberland Caverns)

10. are parallel to a valley with a master stream. The large cave passages are hypothesized to be a
result of subsurface diversion of the master stream. This leaves the large, horizontal passages of
the Cumberland-style caves subject to high discharge which further enlarges the caves (Figure
6).
Plateau-margin and Cumberland-style caves are similar because they require high
discharge conditions to create their large, low-gradient horizontal passages. Large, multilevel
caves on the western margin of the Cumberland Plateau have been thought to be created during
long periods of river stability. The abandoned trunks in both cave models are speculated to have
formed at any time during the past when hydrologic conditions were correct (Anthony &
Granger 47).
Resurgences of subsurface streams also occur at the base of the Monteagle limestone
which is made up of a relatively resistant and impermable layer of chert and shale. These layers
act as a control for many of the large formations within the Cumberland Plateau. Sometimes,
streams are capable of breaching this control. If they do, they will drop onto the St. Louis
limestone below where they usually resurge on top of layers of shale and dolomite.
The lowest control for the Cumberland Plateau subsurface streams is the top of the
Warsaw limestone below the St. Louis limestone. The Warsaw limestone is sandy so when it
leaches into the sandstone, it often outcrops as a sandy bench along major streams that flow at
the base of the escarpment. The water table at the base of the escarpment can be determined by
the location of the resurgent stream. This location is where the last impermeable strata layer
exists.

11. As described, the surface streams that invade the caprock pass through may layers of
different rock. This allows the water to filter multiple times before it leaves the escarpment
through a resurgent stream or spring once it reaches an impermeable layer. There is a cave spring
on Fall Creek Falls property that has been tested and its water quality is almost perfect. The
water filters through the Lost Creek Cove Cave system that I worked. This summer, I had the
opportunity to collect some water from it to drink. It was the coldest, freshest, water I have had
from a natural spring proving that these subterranean worlds are very efficient natural filtration
systems.
CONCLUSIONS:
The Cumberland Plateau is an eastward retreating escarpment made of Mississippian and
Pennsylvanian formations. The sandstone caprock of the plateau covers a karst limestone
landscape below. Intricate subterranean stream systems create caves, passages, domepits, and
even underground waterfalls. The plateau is bounded by a sinkhole plain and Eastland Highland
Rim to the West and the Appalachian Ridge & Valley physiographic region to the East. The
landscape of the plateau is beautiful but below ground is enchanting. It has taken millions of
years for the plateau to become what it is today in modern landscape. The TAG region has a
composition ideal for cave formation, leaving it spotted with 14,000 caves waiting to be
explored.
SOURCES:
Anthony, Darlene M., and Darryl E. Granger. "A Late Tertiary Origin for Multilevel
Caves along the Western Escarpment of the Cumberland Plateau, Tennessee." Journal of Cave
and Karst Studies 66.2 (2004): 46-47.

12. Crawford, Nicholas C. "Subterranean Stream Invasion, Conduit Cavern Development, & Slope
Retreat." The Karst Hydrogeology of the Cumberland Plateau Escarpment of Tennessee.
1st ed. Vol. 44. State of TN, Dept. of Conservation, Division of Geology, 1987. Print.
Des Jean, Tom, and Chaney, Dan. Fossils of Big South Fork; The Paleontological
Resources of the Upper Cumberland Plateau. Geoscientists-In-the-Parks
document, 2003-BISO. National Park Service, Denver, Colorado.
Ford, D. C., and R. O. Ewers. "The Development of Limestone Cave Systems in the Dimensions
of Length and Depth." Canadian Journal of Earth Sciences 15.11: 1783-789. Print.
Wilson, Jr., Charles W., and Richard G. Stearns. "Structure of the Cumberland Plateau,
Tennessee." The Geological Society of America 69.10 (1958): 1283-296. Print.