Flowstone
Encyclopedia
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
formed where water flows down the walls or along the floors of a cave
Cave
A cave or cavern is a natural underground space large enough for a human to enter. The term applies to natural cavities some part of which is in total darkness. The word cave also includes smaller spaces like rock shelters, sea caves, and grottos.Speleology is the science of exploration and study...
. They are typically found in "solution", or 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....
caves, where they are the most common speleothem
Speleothem
A speleothem , commonly known as a cave formation, is a secondary mineral deposit formed in a cave. Speleothems are typically formed in limestone or dolostone solutional caves.-Origin and composition:...
. 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.
Flowing films of water that move along floors or down positive-sloping walls build up layers of calcium carbonate (calcite), aragonite
Aragonite
Aragonite is a carbonate mineral, one of the two common, naturally occurring, crystal forms of calcium carbonate, CaCO3...
, gypsum
Gypsum
Gypsum is a very soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is found in alabaster, a decorative stone used in Ancient Egypt. It is the second softest mineral on the Mohs Hardness Scale...
, or other cave mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
s. These minerals are dissolved in the water and are deposited when the water loses its dissolved carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
through the mechanism of agitation, meaning it can no longer hold the minerals in solution. The flowstone forms when thin layers of these deposits build on each other, sometimes becoming rounder as the deposit gets thicker.
There are two common forms of flowstones, tufa
Tufa
Tufa is a variety of limestone, formed by the precipitation of carbonate minerals from ambient temperature water bodies. Geothermally heated hot-springs sometimes produce similar carbonate deposits known as travertine...
and travertine
Travertine
Travertine is a form of limestone deposited by mineral springs, especially hot springs. Travertine often has a fibrous or concentric appearance and exists in white, tan, and cream-colored varieties. It is formed by a process of rapid precipitation of calcium carbonate, often at the mouth of a hot...
. Tufa is usually formed via the precipitation of calcium carbonate and is spongy or porous in nature. Travertine is a calcium carbonate deposit often formed in creeks or rivers, its nature is laminated and includes such structures as stalagmites and stalactites.
The deposits may grade into thin sheets called "draperies" or "curtains" where they go over overhanging portions of the wall. Some draperies are translucent, and some have brown and beige layers that look much like bacon
Bacon
Bacon is a cured meat prepared from a pig. It is first cured using large quantities of salt, either in a brine or in a dry packing; the result is fresh bacon . Fresh bacon may then be further dried for weeks or months in cold air, boiled, or smoked. Fresh and dried bacon must be cooked before eating...
(often termed "cave bacon").
Though flowstones are among the largest of speleothems, they can still be damaged by a single touch. The oil from human fingers causes the water to avoid the area, which then dries out. Flowstones are also good identifiers of periods of past droughts, since they need some form of water to precipitate, the lack of that water for long periods of time can leave traces in the rock record via flowstones.
Gallery
File:CaveBacon.jpg|Cave Bacon in the Caverns of Sonora
Caverns of Sonora
The Caverns of Sonora, a National Natural Landmark, is a unique cave located west of the small city of Sonora, the seat of Sutton County, Texas. It is a world-class cave because of its stunning array of calcite crystal formations, especially helictites. These helictites are found in extreme...
near Sonora, Texas
Sonora, Texas
Sonora is the county seat of Sutton County, Texas, United States. The population was 2,924 at the 2000 census.Former State Senator and Lieutenant Governor Bill Ratliff of Mount Pleasant was reared in Sonora and graduated from high school there.-Geography and climate:Sonora is located at ...
File:Tica drapery.jpg|Flowstone Drapery in Middle Cave, Timpanogos Cave NM