A sump or siphon is a passage in a cave, submerged under water. A sump may be active, with continuous through-flow. Static sumps may be connected underwater to active stream passage; when short in length, a sump may be called a duck. Short sumps may be passed by holding one's breath while ducking through the submerged section; this is known as "free diving" and can only be attempted if the sump is known to be short and not technically difficult. Longer and more technically difficult sumps can only be passed by cave diving; when practical, a sump can be drained using buckets, pumps or siphons. Pumping the water away requires the inward flow of water into the sump to be less than the rate at which the pump empties it, as well as a suitable place to collect the emptied water. Upstream sumps have been emptied using hoses to siphon water out of them, such as at the Sinkhole Dersios during exploration in 2005; the water was sent deeper into the sinkhole and the emptied sumps revealed virgin passage behind them.
During a rescue from beyond a downstream sump at Sarkhos Cave in 2002, water was pumped upstream into a dam constructed a few metres above the flooded passage. Some manuals mention the use of explosives or other forms of force to empty sumps, but the ecological damage done to the fragile cave environment rules out the use of such methods. Phreatic zone – The area in an aquifer below the water table
Calcite crystals form on the surface of quiescent bodies of water when the bulk water is not supersaturated with respect to calcium carbonate. The crystals attach to one other and appear to be floating rafts of a white, opaque material; the floating materials have been referred to as calcite rafts or "leopard spots". Calcium carbonate is known to precipitate as calcite crystals in water supersaturated with calcium and carbonate ions. Under quiescent conditions, calcite crystals can form on a water surface when calcium carbonate supersaturation conditions do not exist in the bulk water. Water evaporates from the surface and carbon dioxide degasses from the surface layer to create a thin layer of water with high pH and concentrations of calcium and carbonate ions far above the saturation concentration for calcium carbonate. Calcite crystals precipitate in this localized environment and attach to one another to form what appear to be rafts of a white material. Scanning electron micrographs of calcite rafts show interconnected calcite crystals formed around holes on the raft surface.
The holes may be caused by other foreign matter on the water surface. Micrographs of calcite rafts show lace-like structure; the surface tension of the water keeps the interconnected calcite crystals, which individually have a specific gravity of 2.7, floating on the water surface. Calcite rafts are most formed in limestone cave systems. Limestone caves provide a favorable environment due to little air movement and water containing significant concentrations of calcium and carbonate ions. Evidence of calcite rafts has been found in limestone caves all over the world. One example of calcite raft formation in a spring-fed river system has been reported. In 2005, the Carpinteria Valley Water District in Carpinteria, raised water quality concerns when "leopard spots" 5 to 10 cm. in diameter appeared on the water surface under a newly constructed aluminum reservoir cover. The floating material had not been observed; the concern raised was that a toxic metallic precipitate was forming on the water surface from condensate dripping from the metal cover.
Water analyses found that the water in the reservoir was saturated with respect to calcium carbonate but no calcite crystals were formed in the bulk solution. X-ray diffraction analysis showed that the floating solid material was greater than 97 percent calcite. Scanning electron micrographs confirmed that the shape of the crystalline material was rhombohedral, consistent with calcite crystal formation. While the floating material was not toxic, it was recommended that movement of the water surface be induced so that quiescent conditions would be avoided which would eliminate the primary condition for calcite raft formation. Micro calcite rafts have been observed on straw stalactites solution drops suspended beneath concrete structures; these secondary deposits which form outside the cave environment, are known as calthemites. They are derived from concrete, lime or mortar, mimic the shapes and forms of speleothems created in caves; the micro rafts which form on the surface of hyperalkaline leachate solution drips are about 0.5 mm in size when visible to the naked eye, appear on the drip’s surface after it has been suspended for greater than ≈5 minutes.
The chemical reaction which creates the rafts, involves carbon dioxide being absorbed into solution from the atmosphere and calcium carbonate precipitates as rafts or deposited as a stalagmite, stalactite or flowstone. This chemistry is different to that which creates speleothems in caves. Internal water pulses from the straw and air movement around the suspended solution drop, can cause the rafts to spin swiftly around the drop surface. If there is no air movement around the suspended drop after 12 minutes or more, the micro rafts may join up and form a latticework, which covers the entire drop surface. If the solution drop hangs too long on the straw, it may calcify over and block the calthemite straw tip. Lubbock Area Grotto Calcite /Raft Accessed 2012-06-23. Karstbase—Calcite raft Kartchner Caverns State Park A short video clip of rafts spinning around a solution drop
A sea cave known as a littoral cave, is a type of cave formed by the wave action of the sea. The primary process involved is erosion. Sea caves are found throughout the world 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; some of the best-known sea caves are European. Fingal's Cave, on the Scottish island of Staffa, is a spacious cave some 70 m long, formed in columnar basalt; the Blue Grotto of Capri, although smaller, is famous for the apparent luminescent quality of its water, imparted by light passing through underwater openings. The Romans built a stairway in a now-collapsed tunnel to the surface.
The Greek islands are noted for the variety and beauty of their sea caves. Numerous sea caves have been surveyed in England, in France on the Normandy coast; until 2013, the largest known sea caves were found along the west coast of the United States, the Hawaiian islands, the Shetland Islands. In 2013 the discovery and survey of the world's largest sea cave was announced. Matainaka Cave - located on the Otago coast of New Zealand's South Island - has proven to be the world's most extensive at 1.5 km in length. In 2013, Crossley reported a newly surveyed complex reaching just over a kilometer in survey at Bethells Beach on New Zealand's North Island. Littoral caves may be found in a wide variety of host rocks, ranging from sedimentary to metamorphic to igneous, but caves in the latter tend to be larger due to the greater strength of the host rock. However, there are some notable exceptions as discussed below. In order to form a sea cave, the host rock must first contain a weak zone. In metamorphic or igneous rock, this is either a fault as in the caves of the Channel Islands of California, or a dike as in the large sea caves of Kauai, Hawaii’s Na Pali Coast.
In sedimentary rocks, this may be a bedding-plane parting or a contact between layers of different hardness. The latter may occur in igneous rocks, such as in the caves on Santa Cruz Island, where waves have attacked the contact between the andesitic basalt and the agglomerate; the driving force in littoral cave development is wave action. Erosion is ongoing anywhere that waves batter rocky coasts, but where sea cliffs contain zones of weakness, rock is removed at a greater rate along these zones; as the sea reaches into the fissures thus formed, they begin to widen and deepen due to the tremendous force exerted within a confined space, not only by direct action of the surf and any rock particles that it bears, but by compression of air within. Blowholes attest to this process. Adding to the hydraulic power of the waves is the abrasive force of suspended sand and rock. Most sea-cave walls are irregular and chunky, reflecting an erosional process where the rock is fractured piece by piece. However, some caves have portions where the walls are rounded and smoothed floored with cobbles, result from the swirling motion of these cobbles in the surf zone.
True littoral caves should not be confused with inland caves that have been intersected and revealed when a sea cliff line is eroded back, or with dissolutional voids formed in the littoral zone on tropical islands. In some regions, such as Halong Bay, caves in carbonate rocks are found in littoral zones, being enlarged by littoral processes but were formed by dissolution; such caves have been termed as hybrid caves. Rainwater may influence sea-cave formation. Carbonic and organic acids leached from the soil may assist in weakening rock within fissures; as in solutional caves, small speleothems may develop in sea caves. Sea cave chambers sometimes collapse leaving a “littoral sinkhole”; these may be quite large, such as Oregon’s Devil’s Punchbowl or the Queen’s Bath on the Na Pali coast. Small peninsulas or headlands have caves that cut through them, since they are subject to attack from both sides, the collapse of a sea cave tunnel can leave a free-standing “sea stack” along the coast; the Californian island of Anacapa is thought to have been split into three islets by such a process.
Life within sea caves may assist in their enlargement as well. For example, sea urchins drill their way into the rock, over successive generations may remove considerable bedrock from the floors and lower walls. Most sea caves are small in relation to other types. A compilation of sea-cave surveys as of July 2014 shows 2 over 1000 meters, 6 over 400 meters, nine over 300 meters, 25 over 200 meters, 108 over 100 meters in length. In Norway, several relict sea caves exceed 300 meters in length. There is no doubt that many other large sea caves exist but have not been investigated due to their remote locations and/or hostile sea conditions. Several factors contribute to the development of large sea caves; the nature of the zone of weakness itself is a factor, although difficult to quantify. A more observed factor is the situation of the cave’s entrance relative to prevailing sea conditions. At Santa Cruz Island, the largest caves face into the prevailing northwest swell conditions—a factor which makes them more difficult to survey.
Caves in well-protected bays sheltered from prevailing seas and wi
In geology, frostwork is a type of speleothem with acicular growths always composed of aragonite or calcite replaced aragonite. It is a variety of anthodite. In some caves frostwork may grow on top of cave boxwork. In architecture frost-work or frostwork refers to a style of rustication carved with a vertically-oriented pattern evoking hanging pond-weed or algae, or icicles, it is found in garden architecture, where water is to flow over or near the surface. Other decorative arts may use the term for other decorative patterns imitating ice; the origin of frostwork is somewhat controversial. Formation of cave frostwork has been attributed to moist, circulating air which, containing dissolved calcium carbonate, drifted against rock surfaces and coated them with the delicate crystals. Frostwork has been attributed to water seepage from cave passageways in which there are high evaporation rates. Notable frostwork deposits are found in a number of caves in the Black Hills region of South Dakota, USA, most notable in Wind Cave National Park and Jewel Cave National Monument and Timpanogos Cave in Utah.
The most extensive displays known are found in Lechuguilla Cave, New Mexico, USA. Wind Cave National Park: Speleothems The Virtual Cave's page on aragonite and frostwork
An underground lake or subterranean lake is a lake under the surface of the Earth. Such lakes may be associated with aquifers, or springs, they are very low in salinity. The largest non-subglacial lake in the world is in Dragon's Breath Cave in Namibia, with an area of 2 hectares, the second largest is in Craighead Caverns in Tennessee, United States. Subglacial lake Subterranean river Subterranean waterfall Media related to Underground lakes at Wikimedia Commons
A foiba — jama in South Slavic languages scientific and colloquial vocabulary — is a type of deep natural sinkhole, doline, or sink, is a collapsed portion of bedrock above a void. Sinks may be a shallow depression of many hectares, they are common in the Kras region shared by Italy and Slovenia, as well as in a karst of Dinaric Alps in Bosnia and Herzegovina and Croatia. The term "foiba" was used in the 1770s by Italian naturalist Alberto Fortis who wrote a number of books about karst of Dalmatia, it is an Italian derivative of the Latin fovea, meaning "pit" or "chasm". They are indeed chasms excavated by water erosion, have the shape of an inverted funnel, can be up to 200 metres deep; such formations number in the hundreds in Istria. In karst areas, a sinkhole, sink, or doline is a closed depression draining underground, it can be cylindrical, bowl-shaped or dish-shaped. The diameter ranges from a few to many hundreds of metres; the name "doline" comes from dolina, the Slovenian word for this common feature.
The term "foiba" may refer to a deep wide chasm of a river at the place where it goes underground. Karst Plateau Corsetto Norma Gardens of the Righteous Worldwide Committee - Gariwo