Shelfstone

Last updated
Shelfstone growing on the edge of a small cave pool Shelfstone2.jpg
Shelfstone growing on the edge of a small cave pool
Shelfstone growths at multiple levels show former stands of the pool in which they formed. Some of the lower shelfstone has pool spar attached to it. Shelfstone1.jpg
Shelfstone growths at multiple levels show former stands of the pool in which they formed. Some of the lower shelfstone has pool spar attached to it.

Shelfstone is a type of speleothem that grows inwards from the edge of a cave pool. It takes the form of ledges that tend to be flat on top and sloping underneath. They are almost always formed from calcite, when materials precipitated from dripping water onto a cave pool attach to the side. The deposition continues to grow laterally, underneath. The shelfstone above the current water level in a pool is an indicator of past levels of the pool. Shelfstone can be very thick when the water level has stayed constant over a long period of time. If the water level is constantly changing, the shelfstone will be thin and delicate.

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

Speleothems, commonly known as cave formations, are secondary mineral deposits formed in a cave. Speleothems typically form in limestone or dolostone solutional caves. The term "speleothem" as first introduced by Moore (1952), is derived from the Greek words spēlaion "cave" + théma "deposit". The definition of "speleothem" in most publications, specifically excludes secondary mineral deposits in mines, tunnels and on man-made structures. Hill and Forti more concisely defined "secondary minerals" which create speleothems in caves as;

A "secondary" mineral is one which is derived by a physicochemical reaction from a primary mineral in bedrock or detritus, and/or deposited because of a unique set of conditions in a cave; i.e., the cave environment has influenced the mineral's deposition.

Calcite carbonate mineral

Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). The Mohs scale of mineral hardness, based on scratch hardness comparison, defines value 3 as "calcite".

Sources

Related Research Articles

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 also refer to much smaller openings such as sea caves, rock shelters, and grottos, though strictly speaking a cave is exogene, meaning it is deeper than its opening is wide, and a rock shelter is endogene.

Karst Topography formed from the dissolution of 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 be totally missing above ground.

Stalactite elongated mineral formation which hangs down from a cave ceiling

A stalactite is a type of formation that hangs from the ceiling of caves, hot springs, or manmade structures such as bridges and mines. Any material that is soluble, 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.

Stalagmite elongated mineral formation which forms 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 may be composed of lava, minerals, mud, peat, pitch, sand, sinter and amberat.

Stack (geology) A geological landform consisting of a steep and often vertical column or columns of rock in the sea near a coast, formed by wave erosion

A stack or sea stack is a geological landform consisting of a steep and often vertical column or columns of rock in the sea near a coast, formed by wave erosion. Stacks are formed over time by wind and water, processes of coastal geomorphology. They are formed when part of a headland is eroded by hydraulic action, which is the force of the sea or water crashing against the rock. The force of the water weakens cracks in the headland, causing them to later collapse, forming free-standing stacks and even a small island. Without the constant presence of water, stacks also form when a natural arch collapses under gravity, due to sub-aerial processes like wind erosion. Erosion causes the arch to collapse, leaving the pillar of hard rock standing away from the coast—the stack. Eventually, erosion will cause the stack to collapse, leaving a stump. Stacks can provide important nesting locations for seabirds, and many are popular for rock climbing.

Soda straw

A soda straw is a speleothem in the form of a hollow mineral cylindrical tube. They are also known as tubular stalactites. Soda straws grow in places where water leaches slowly through cracks in rock, such as on the roofs of caves. Soda straws in caves rarely grow more than a few millimetres per year and may average one tenth of a millimetre per year. A soda straw can turn into a stalactite if the hole at the bottom is blocked, or if the water begins flowing on the outside surface of the hollow tube.

Luray Caverns landform

Luray Caverns, originally called Luray Cave, is a cave just west of Luray, Virginia, United States, which has drawn many visitors since its discovery in 1878. The cavern system is generously adorned with speleothems such as columns, mud flows, stalactites, stalagmites, flowstone, and mirrored pools. The caverns are perhaps best known for the Great Stalacpipe Organ, a lithophone made from solenoid-fired strikers that tap stalactites of various sizes to produce tones similar to those of xylophones, tuning forks, or bells.

Tide pool A rocky pool on a seashore, separated from the sea at low tide, filled with seawater

Tide pools or rock pools are shallow pools of seawater that form on the rocky intertidal shore. Many of these pools exist as separate bodies of water only at low tide.

Formation may refer to:

Dogtooth spar

Dogtooth spar is a speleothem found in limestone caves that consists of very large calcite crystals resembling dogs' teeth. They form through mineral precipitation of water-borne calcite. Dogtooth spar crystals are not limited to caves, but can grow in any open space including veins, fractures, and geodes.

Coastal geography The study of the region between the ocean and the land

Coastal geography is the study of the constantly changing region between the ocean and the land, incorporating both the physical geography and the human geography of the coast. It includes understanding coastal weathering processes, particularly wave action, sediment movement and weather, and the ways in which humans interact with the coast

Anchialine pool A landlocked body of water with a subterranean connection to the ocean.

An anchialine pool or pond is a landlocked body of water with a subterranean connection to the ocean. Anchialine pools are a feature of coastal aquifers which are density stratified, with the water near the surface being fresh or brackish, and saline water intruding from the coast below at some depth. Depending on the site, it is sometimes possible to access the deeper saline water directly in the anchialine pool or sometimes it may be accessible by cave diving.

Marble Arch Caves cave

The Marble Arch Caves are a series of natural limestone caves located near the village of Florencecourt in County Fermanagh, Northern Ireland. The caves are named after the nearby Marble Arch, a natural limestone arch at the upstream end of Cladagh Glen under which the Cladagh River flows. The caves are formed from three rivers draining off the northern slopes of Cuilcagh mountain, which combine underground to form the Cladagh. On the surface, the river emerges from the largest karst resurgence in Ireland, and one of the largest in the United Kingdom. At 11.5 kilometres (7.1 mi) the Marble Arch Caves form the longest known cave system in Northern Ireland, and the karst is considered to be among the finest in the British Isles.

Priddy Pools

Priddy Pools is a 52.7-hectare (130-acre) geological Site of Special Scientific Interest at Priddy in the Mendip Hills, Somerset, notified in 1972.

St Cuthberts Swallet

St Cuthbert's Swallet is the second longest, and most complex, cave on the Mendip Hills, in Somerset, England. It forms a major part of the Priddy Caves system and water entering this swallet re-emerges at Wookey Hole. St Cuthbert's Swallet is part of, and lies underneath, the Priddy Pools Site of Special Scientific Interest. In the citation this is given as St Cuthbert's Cave, which should not be confused with St Cuthbert's Cave in Northumberland.

Rimstone

Rimstone, also called gours, is a type of speleothem in the form of a stone dam. Rimstone is made up of calcite and other minerals that build up in cave pools. The formation created, which looks like stairs, often extends into flowstone above or below the original rimstone. Often, rimstone is covered with small, micro-gours on horizontal surfaces. Rimstone basins may form terraces that extend over hundreds of feet, with single basins known up to 200 feet long from Tham Xe Biang Fai in Laos

Cave pearl

A cave pearl is a small, usually spherical, speleothem found in limestone caves. Cave pearls are formed by a concretion of calcium salts that form concentric layers around a nucleus. Exposure to moving water polishes the surface of cave pearls, making them glossy; if exposed to the air, cave pearls can degrade and appear rough.

Devils Den Cave

Devil's Den is formed by a karst window, in which the roof over a subterranean river has collapsed, exposing the water to the open surface, near Williston, Florida. It is privately owned, and operated as a SCUBA diving training and recreational facility.

Falemauga Caves

The Falemauga Caves are large natural caverns in a series of lava-tunnels situated in the Tuamasaga district along the central ridge of Upolu island in Samoa. The caves have been studied by archaeologists in Samoa with evidence of human occupation in pre-history. They were also used as a place of refuge by the people of Tuamasaga.