Speleogen

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Speleogens in a West Virginia cave Spleogens wv.jpg
Speleogens in a West Virginia cave

A speleogen is a geological feature within a karst system that is created by the dissolution of bedrock. As rain water falls through the atmosphere it picks up carbon dioxide and more as it passes through organic material in the soil. As water moves through joints and cracks in calcium carbonate bedrock, more dissolution of the bedrock occurs and the bedrock features that are left are the speleogens. This process called speleogenesis is what leads to secondary formations or speleothems. [1]

The United States Code defines speleogens as "relief features on the walls, ceiling, and floor of any cave or lava tube which are part of the surrounding bedrock, including anastomoses, scallops, meander niches, petromorphs and rock pendants in solution caves and similar features unique to volcanic caves." [2]

"Speleogens are irregular or distinctive shapes of carbonate rock etched from bedrock by dripping or running water. Speleogens can form where bedrock is not uniform in chemical composition. Consequently, the less soluble rock dissolves slower than adjacent more soluble rock through time. The less soluble rock tends to stand in relief and projects from walls and ceilings of caves." [3]

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Cave Natural underground space large enough for a human to enter

A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word cave can refer to smaller openings such as sea caves, rock shelters, and grottos, that extend a relatively short distance into the rock and they are called exogene caves. Caves which extend further underground than the opening is wide are called endogene caves.

Karst Topography from dissolved soluble rocks

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 rocks, such as quartzite, given the right conditions. Subterranean drainage may limit surface water, with few to no rivers or lakes. However, in regions where the dissolved bedrock is covered or confined by one or more superimposed non-soluble rock strata, distinctive karst features may occur only at subsurface levels and can be totally missing above ground.

Limestone Sedimentary rocks made of calcium carbonate

Limestone is a common 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 calcium carbonate. Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils, and these provide scientists with information on ancient environments and on the evolution of life.

Stalactite Elongated mineral formation hanging down from a cave ceiling

A stalactite (, ; from the Greek 'stalaktos' via stalassein is a mineral formation that hangs from the ceiling of caves, hot springs, or man-made structures such as bridges and mines. Any material that is soluble and that can be deposited as a colloid, or is in suspension, or is capable of being melted, may form a stalactite. Stalactites may be composed of lava, minerals, mud, peat, pitch, sand, sinter, and amberat. A stalactite is not necessarily a speleothem, though speleothems are the most common form of stalactite because of the abundance of limestone caves.

Sinkhole Geologically-formed topological depression

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 openings where surface water enters into underground passages known as ponor, swallow hole or swallet. A cenote is a type of sinkhole that exposes groundwater underneath. A sink or stream sink are more general terms for sites that drain surface water, possibly by infiltration into sediment or crumbled rock.

Stalagmite Elongate mineral formation found on a cave floor

A stalagmite is a type of rock formation that rises from the floor of a cave due to the accumulation of material deposited on the floor from ceiling drippings. Stalagmites are typically composed of calcium carbonate, but may consist of lava, mud, peat, pitch, sand, sinter, and amberat.

Travertine Form of limestone deposited by mineral springs

Travertine is a form of terrestrial limestone deposited around mineral springs, especially hot springs. It often has a fibrous or concentric appearance and exists in white, tan, cream-colored, and even rusty varieties. It is formed by a process of rapid precipitation of calcium carbonate, often at the mouth of a hot spring or in a limestone cave. In the latter, it can form stalactites, stalagmites, and other speleothems. It is frequently used in Italy and elsewhere as a building material.

Speleothem Structure formed in a cave by the deposition of minerals from water

A speleothem is a geological formation by mineral deposits that accumulate over time in natural caves. Speleothems most commonly form in calcareous caves due to carbonate dissolution reactions. They can take a variety of forms, depending on their depositional history and environment. Their chemical composition, gradual growth, and preservation in caves make them useful paleoclimatic proxies.

Cenote Natural pit or sinkhole that exposes groundwater underneath

A cenote is a natural pit, or sinkhole, resulting from the collapse of limestone bedrock that exposes groundwater. The regional term is specifically associated with the Yucatán Peninsula of Mexico, where cenotes were commonly used for water supplies by the ancient Maya, and occasionally for sacrificial offerings. The term derives from a word used by the lowland Yucatec Maya—tsʼonot—to refer to any location with accessible groundwater.

Dolomite (rock) Sedimentary carbonate rock that contains a high percentage of the mineral dolomite

Dolomite (also known as dolomite rock, dolostone or dolomitic rock) is a sedimentary carbonate rock that contains a high percentage of the mineral dolomite, CaMg(CO3)2. It occurs widely, often in association with limestone and evaporites, though it is less abundant than limestone and rare in Cenozoic rock beds (beds less than about 66 million years in age). The first geologist to distinguish dolomite rock from limestone was Belsazar Hacquet in 1778.

Flowstone Archaeological phenomenon

Flowstones are sheetlike deposits of calcite or other carbonate minerals, formed where water flows down the walls or along the floors of a cave. They are typically found in "solution caves", in limestone, where they are the most common speleothem. However, they may form in any type of cave where water enters that has picked up dissolved minerals. Flowstones are formed via the degassing of vadose percolation waters.

<i>Gongshi</i>

Gongshi, also known as scholar's rocks, are naturally occurring or shaped rocks which are traditionally appreciated by Chinese scholars.

Carbonate rock Class of sedimentary rock

Carbonate rocks are a class of sedimentary rocks composed primarily of carbonate minerals. The two major types are limestone, which is composed of calcite or aragonite (different crystal forms of CaCO3), and dolomite rock (also known as dolostone), which is composed of mineral dolomite (CaMg(CO3)2).

Sea cave Cave formed by the wave action of the sea and located along present or former coastlines

A sea cave, also known as a littoral cave, is a type of cave formed primarily by the wave action of the sea. The primary process involved is erosion. Sea caves are found throughout the world, actively forming along present coastlines and as relict sea caves on former coastlines. Some of the largest wave-cut caves in the world are found on the coast of Norway, but are now 100 feet or more above present sea level. These would still be classified as littoral caves. By contrast, in places like Thailand's Phang Nga Bay, solutionally formed caves in limestone have been flooded by the rising sea and are now subject to littoral erosion, representing a new phase of their enlargement.

Speleogenesis is the origin and development of caves, the primary process that determines essential features of the hydrogeology of karst and guides its evolution. It often deals with the development of caves through limestone, caused by the presence of water with carbon dioxide dissolved within it, producing carbonic acid which permits the dissociation of the calcium carbonate in the limestone.

Texella reddelli, the Bee Creek cave harvestman, is a rare species of troglobitic harvestman that was added to the United States endangered species list in 1988, at the same time as six other species native to the karst ecosystem in Travis County and Williamson County, Texas, USA. They inhabit areas with near 100% humidity and constant temperatures, and they prey on springtails. Since they can only be found underground, research on these creatures has been difficult. Their distribution is limited and unknown reproductive rates mean that it is possible they are especially susceptible to habitat destruction and other threats. Texella reddelli are found on both the North and South sides of the Colorado River.

Solutional cave Type of cave

A solutional cave, solution cave, or karst cave is a cave usually formed in the soluble rock limestone. It is the most frequently occurring type of cave. It can also form in other rocks, including chalk, dolomite, marble, salt beds, and gypsum.

There are a number of terms that are used in connection with caves, caving and speleology. The following is an incomplete list.

Cedar Sink

Cedar Sink is a vertical-walled large depression, or sinkhole, in the ground, that is located in Edmonson County, Kentucky and contained within and managed by Mammoth Cave National Park. The sinkhole measures 300 feet (91.4 m) from the top sandstone plateau to the bottom of the sink and was caused by collapse of the surface soil. The landscape is karst topography, which means the region is influenced by the dissolution of soluble rocks. Sinkholes, caves, and dolines typically characterize these underground drainage systems. Cedar Sink has a bottom area of about 7 acres (2.8 ha) and has more fertile soil compared to the ridgetops.

Fissure Long, narrow crack opening on a planetary surface

A fissure is a long, narrow crack opening along the surface of Earth. The term is derived from the Latin word fissura, which means 'cleft' or 'crack'. Fissures emerge in Earth's crust, on ice sheets and glaciers, and on volcanoes.

References

  1. Ford, Derek. "Karst hydrology and geomorphology" (PDF). wordpress.com. John Wiley and Sons, ltd.
  2. "U.S. Code Title 16, Conservation; Chapter 63, Federal Cave Resources Protection § 4302". Legal Information Institute, Cornell University Law School. Retrieved February 14, 2011.
  3. Alpha, Tan Rho; Galloway, John; Tinsley, John. "Karst topography" (PDF). www.pubs.usgs.gov. USGS.