Cedar Sink is a vertical-walled large depression, or

sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...

, in the ground, that is located in

Edmonson County, Kentucky Edmonson County is a county located in the south central portion of the U.S. state of Kentucky. As of the 2020 census, the population was 12,126. Its county seat is Brownsville. The county was formed in 1825 and named for Captain John "Jack" ...

and contained within and managed by

Mammoth Cave National Park Mammoth Cave National Park is an American national park in west-central Kentucky, encompassing portions of Mammoth Cave, the longest cave system known in the world. Since the 1972 unification of Mammoth Cave with the even-longer system under F ...

. The sinkhole measures from the top sandstone plateau to the bottom of the sink and was caused by collapse of the surface soil. The landscape is

karst Karst is a topography formed from the dissolution of soluble rocks such as limestone, Dolomite (rock), dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathe ...

topography, which means the region is influenced by the dissolution of

soluble In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubi ...

rocks. Sinkholes, caves, and dolines typically characterize these underground drainage systems. Cedar Sink has a bottom area of about and has more fertile soil compared to the ridgetops.

Geomorphology

Rock age

The rocks of Cedar Sink and the surrounding area are from the Mississippian (also known as Lower Carboniferous or Early Carboniferous) subperiod that occurred 358.9 to 323.2 million years ago.

Cedar Sink formation

The

Big Clifty Sandstone The Big Clifty Sandstone is a geologic formation in Illinois and Kentucky. It is a subunit of the Golconda Formation in Kentucky and is correlative with the Fraileys Shale to which it grades to in southern Illinois. The Big Clifty and Golconda are ...

caprock Caprock or cap rock is a more resistant rock type overlying a less resistant rock type,Kearey, Philip (2001). ''Dictionary of Geology'', 2nd ed., Penguin Reference, London, New York, etc., p. 41.. . analogous to an upper crust on a cake that is ha ...

has been breached exposing the

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 w ...

Girkin Formation resulting in a relief between approximately below the main plateau surface. The bottom of the sink lies another below and exposes the top of the Ste. Genevieve Limestone. The weakening of the ceiling from the breaching of the caprock and the formation of Smith, Cedar Spring, and Woolsey Valleys caused the ancestral master trunk to collapse. Continuous flow in the master drainage line further undermined the sink and triggered further collapse. Collapse sinkholes, like Cedar Sink, form after an initial subsurface collapse occurs. This collapse commonly happens at the intersection of two passages underground where the roof span is the widest and therefore weakest. The process continues as the underground stream repeatedly undercuts the cave walls, inducing collapse of the weight-bearing

cantilever A cantilever is a rigid structural element that extends horizontally and is supported at only one end. Typically it extends from a flat vertical surface such as a wall, to which it must be firmly attached. Like other structural elements, a cant ...

beams resulting in a wider passage. Erosion continues and eventually the void reaches the surface. Water in an ephemeral stream can be seen from the overlook and occasionally at six other places within this sink, based on the season and recent precipitation events. Exposure of the subsurface stream makes Cedar Sink a karst window or

Karst fenster A karst window, also known as a karst fenster, is a geomorphic feature found in karst landscapes where an underground river is visible from the surface within a sinkhole. In this feature, a spring emerges, then the discharge abruptly disappears int ...

. Cedar Sink is derived chiefly from two similar-sized sub-basins: Mill Hole and Procter Cave. Prior to the major storm of May 1984, all the water from Cedar Sink flowed only to Turnhole Spring.

Karst topography

Cedar Sink area is

karst topography Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant ro ...

. Karst topography is a landscape formed from the dissolution of soluble rocks such as

dolomite Dolomite may refer to: *Dolomite (mineral), a carbonate mineral *Dolomite (rock), also known as dolostone, a sedimentary carbonate rock *Dolomite, Alabama, United States, an unincorporated community *Dolomite, California, United States, an unincor ...

, and

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywa ...

. It is characterized by underground drainage systems with sinkholes, dolines, and caves. The development of karst occurs when acidic water chemically and physically breaks down the rock surface. The acidic water is created when atmospheric

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...

and falling precipitation create a weak carbonic acid ( H2CO3). This process occurs near the bedrock cracks or bedding planes. Over time, the fractures will widen and eventually create a drainage system network in the bedrock. The karst landscape will continue to develop over time as the water wears away at the rocks. Karst

aquifer An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials ( gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characte ...

s display drainage characteristics that in many ways appear similar to surface networks. Scientists have studied parameters of surface-water

hydrology Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and environmental watershed sustainability. A practitioner of hydrology is call ...

and

geomorphology Geomorphology (from Ancient Greek: , ', "earth"; , ', "form"; and , ', "study") is the scientific study of the origin and evolution of topographic and bathymetric features created by physical, chemical or biological processes operating at or ...

for years, but it was not until recently that the underground water system was understood. Extensive drainage-network analysis using GIS and other tools has developed a more well-rounded view of the karst topography and the subsurface hydrologic influences occurring in Mammoth Caves National Park. Over the past four decades, an extensive investigation of the Mammoth Cave Watershed useful for providing the opportunity for broader quantitative research in the organization of a large, highly developed, karst-drainage network.

Ecology

The abundance of fertile soils with high water content allows for high vegetative amounts in and around Cedar Sink. Some scientists have proposed that more mesic woods may have existed before settlement. Frequent species include ''

Acer saccharum ''Acer saccharum'', the sugar maple, is a species of flowering plant in the soapberry and lychee family Sapindaceae. It is native to the hardwood forests of eastern Canada and eastern United States. Sugar maple is best known for being the pri ...

''/ ''nigrum'' and ''

Carya cordiformis ''Carya cordiformis'', the bitternut hickory, also called bitternut or swamp hickory, is a large pecan hickory with commercial stands located mostly north of the other pecan hickories. Bitternut hickory is cut and sold in mixture with the true h ...

'' in the more protected areas on richer soils. With the introduction of intense farming and ungulate browsing, previous to the creation of the national park status, the ecosystem changed from a relatively stable "

climax Climax may refer to: Language arts * Climax (narrative), the point of highest tension in a narrative work * Climax (rhetoric), a figure of speech that lists items in order of importance Biology * Climax community, a biological community t ...

" to a greatly modified ecosystem. Other trees in the Cedar Sink area include ''

Liriodendron ''Liriodendron'' () is a genus of two species of characteristically large trees, deciduous over most of their populations, in the magnolia family (Magnoliaceae). These trees are widely known by the common name tulip tree or tuliptree for their ...

'', ''

Quercus muhlenbergii ''Quercus muehlenbergii'', the chinquapin (or chinkapin) oak, is a deciduous species of tree in the white oak group (''Quercus'' sect. ''Quercus''). The species was often called ''Quercus acuminata'' in older literature. ''Quercus muehlenbergii ...

'' and '' Ulmus rubra'' (perhaps ''

Aesculus glabra ''Aesculus glabra'', commonly known as Ohio buckeye,''Aesculus g ...

'', ''

Tilia americana ''Tilia americana'' is a species of tree in the family Malvaceae, native to eastern North America, from southeast Manitoba east to New Brunswick, southwest to northeast Oklahoma, southeast to South Carolina, and west along the Niobrara River to ...

''). Shrubby species include ''

Asimina ''Asimina'' is a genus of small trees or shrubs described as a genus in 1763. ''Asimina'' is the only temperate genus in the tropical and subtropical flowering plant family, Annonaceae. ''Asimina'' has large simple leaves and large fruit. It is ...

'' and ''

Lindera Dried fruits of ''Lindera neesiana'' used as spice (coll. MHNT) ''Lindera'' is a genus of about 80–100Athyrium pycnocarpon'', ''

Cinna arundinacea Cinna may refer to: * Cornelii Cinnae, an ancient Roman family :* Lucius Cornelius Cinna, Roman consul four consecutive times in the 80s BC and at the time of his death the father-in-law of Julius Caesar :* Gnaeus Cornelius Cinna Magnus, a consp ...

'', ''

Microstegium vimineum ''Microstegium vimineum'', commonly known as Japanese stiltgrass, packing grass, or Nepalese browntop, is an annual grass that is common in a wide variety of habitats and is well adapted to low light levels. Despite being non-native in the Unite ...

'', '' Eupatorium rugosum'', '' Festuca subverticillata'' (''obtusa''), ''

Monarda ''Monarda'' is a genus of flowering plants in the mint family, Lamiaceae.Harley, R. M., et al. 2004. "Labiatae". pp 167-275 In: Kubitzki, K. (editor) and J. W. Kadereit (volume editor). ''The Families and Genera of Vascular Plants'' volume VII. ...

'' species (the undescribed mid-western variant of '' clinopodia''), ''

Pilea pumila ''Pilea pumila'', commonly known as clearweed, Canadian clearweed, coolwort or richweed, is an herbaceous plant in the nettle family (Urticaceae). It is native to Asia and eastern North America, where it is broadly distributed. This plant is mos ...

'', '' Polygonum virginianum'', '' Solidago flexicaulis'', '' Tradescantia subaspera'', ''

Verbesina alternifolia ''Verbesina alternifolia'' is a species of flowering plant in the family Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. ...

''. Cedar Sink area has many organisms including the '' Chologaster agassizii'', a spring cavefish which is endemic to Lebanon Tennessee and Mammoth Caves National Park. Other organisms include: question mark butterfly, tussock moth,

red-spotted purple ''Limenitis arthemis,'' the red-spotted purple or white admiral, is a North American butterfly species in the cosmopolitan genus ''Limenitis''. It has been studied for its evolution of mimicry, and for the several stable hybrid wing patterns wi ...

and red admiral. Some common plants and flowering plants include: Christmas ferns, walking ferns, thimbleweed, cranefly orchid, phlox, tick trefoil,

agrimony ''Agrimonia'' (from the Greek ), commonly known as agrimony, is a genus of 12–15 species of perennial plant, perennial herbaceous flowering plants in the family Rosaceae, native to the temperate regions of the Northern Hemisphere, with one sp ...

, poison ivy, '' Hypericum perforatum'' ( St. John's wort), starry campion, tall bellflower, spiderworts, white avens, white tick trefoil, lopseed, pale-spiked lobelia, ''

Ruellia ''Ruellia'' is a genus of flowering plants commonly known as ruellias or wild petunias. They are not closely related to petunias (''Petunia'') although both genera belong to the same euasterid clade. The genus was named in honor of Jean Ruelle ...

'' (wild petunia), pale Indian plantain and ''

Prunella vulgaris ''Prunella vulgaris'', the common self-heal, heal-all, woundwort, heart-of-the-earth, carpenter's herb, brownwort or blue curls, is a herbaceous plant in the mint family Lamiaceae. Self-heal is edible: the young leaves and stems can be eaten raw ...

''. ''

Lactarius ''Lactarius'' is a genus of mushroom-producing, ectomycorrhizal fungi, containing several edible species. The species of the genus, commonly known as milk-caps, are characterized by the milky fluid ("latex") they exude when cut or damaged. Like ...

'' is a common mushroom found around Cedar Sink.

Recreation and activities

Hiking

The trail to Cedar Sink follows the Smith Valley floor for about ¾ mile. The trail is 1.6 miles round trip and circles the southern edge of the sink and eventually leads to a platform overlooking the sink. The trail is clearly delineated with many stairs leading to the bottom of the sink and there are several vista platforms along the ridge. The trail offers many glimpses at the once underground river system. The views from the plateau change depending on the weather; there are many ephemeral springs at the south end of the sink. The overflow route is dry at times and flowing strongly at other during high precipitation events. The main channel flow is often not at the surface throughout many parts of this region.

Geocaching

Geocaching is also a common treasure-hunt like recreation activity in Cedar Sink. Several caches are hidden in Cedar Sink and Mammoth Caves area.

References

{{coord, 37.150278, -86.153631, type:landmark_region:US-KY, display=title Mammoth Cave National Park Landforms of Edmonson County, Kentucky Sinkholes of the United States

Geomorphology

Rock age

Cedar Sink formation

Karst topography

Ecology

Recreation and activities

Hiking

Geocaching

See also

References