Shallow subterranean habitats

Tanja Pipan , David C. Culver , in Encyclopedia of Caves (Third Edition), 2019

Lava tubes

Lava tubes are by-products of volcanic processes themselves. They form either as the issue of surface cooling of lava flows or the result of sequential lava flows, with afterward flows going underneath the older ones and cavities by a process chosen inflation. Lava tubes are known throughout the world, in areas of volcanic action along moving plates of the Earth'southward crust. Typically, lava tubes form very close to the surface, and are long tubes of more than or less constant diameter. Kazumura Cave in Hawai'i, is the longest known lava tube, with 65  km of passage and 101 entrances, and rarely if ever is more than than x   m beneath the surface. La Cueva del Viento in the Canary Islands, 1 of the world almost diverse caves with respect to terrestrial troglobionts (Culver and Pipan, 2013), is over 20   km long but is at a depth of betwixt 2.5 and seven   m from the surface. In both the Hawaiian Islands and the Canary Islands, where the fauna has been all-time studied, roots of copse break through the roof of the lava tubes, and at least in Hawai'i, they are a main source of food. At that place are some lava tubes that are deeper than 10   m, and some features of volcanic landscapes, including pit craters and open volcanic conduits are very deep (sometimes greater than 100   k (Palmer, 2007)), but most of what we know about subterranean habitats in lava is from shallow lava tubes and the MSS habitats associated with lava flows. Hence, we include them as SSHs (Culver and Pipan, 2014). Every bit with other SSHs and caves, environmental variation is reduced in lava tubes. We found that temperature 400   m inside Cueva del Viento varied slightly more than 2°C over the form of year with no detectable daily variation (Culver and Pipan, 2014).

In Hawai'i, the food web in many lava tubes is dominated by roots of Metrosideros polymorpha, and its main plant eater, planthoppers in the genus Oliarus (encounter Rock et al., 2012). Approximately 40 species of troglobionts are known from the Hawaiian Islands, virtually of which are ultimately dependent on the roots of Metrosideros. The fauna of the Canary Islands is much more than diverse, even though at that place are fewer visible tree roots in lava tubes at that place. Most 130 troglobiotic species are known from the Canary Islands, and the species limerick of the two regions is quite different (Fig. 12). Among the possible reasons for the greater species richness in the Canaries is their greater historic period and their shallower depth, which may event in more organic matter in the lava tubes in the Canaries. The lava tube fauna is also of general evolutionary involvement, because species were not forced into caves by any climatic events such every bit Pleistocene glaciation, but rather actively invaded caves, in part every bit a more beneficial environment than the harsh surface conditions on lava flows (Howarth, 1980).

Fig. 12

Fig. 12. Pie diagrammatic representations of species richness of troglobionts from the Canary Islands and Hawaiian Islands. At that place were 128 species from the Canary Islands and 37 species from the Hawaiian Islands.

 (Compiled by Culver, D.C., Pipan, T., 2014. Shallow Subterranean Habitats. Environmental, Evolution and Conservation. Oxford University Printing, Oxford.)

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Volcanic Landforms and Hazards☆

W.D. Huff , L.A. Owen , in Reference Module in Earth Systems and Environmental Sciences, 2015

Lava tubes

Lava tubes are natural conduits through which lava travels below the surface of a lava period. Tubes form past the crusting over of lava channels and pahoehoe flows ( Figure xv ). During long-lived eruptions, lava flows tend to go channeled into a few main streams. Overflows of lava from these streams solidify quickly and plaster on to the channel walls, edifice natural levees or ramparts that let the level of the lava to be raised. Lava streams that flow steadily in a confined channel for many hours to days may develop a solid crust or roof and, thus, change gradually into streams within lava tubes. Lava tubes are very efficient transporters of lava from the vent to the flow front, and calculations show that lava flowing in a tube cools past only most 1   °C   km−   1 (Walker, 1991). At the flow front, the lava behaves much like a river delta, forming small-scale distributary tubes that continue to branch until they consist of the same type of single flow-unit of measurement tubes, simply smaller, that have been forming the period the whole way downslope. The amount of gas in lava at the period front is somewhat lower than that at the vent, considering, although lava tubes are expert thermal insulators, they are not so well sealed that gas can exist trapped. Gas escapes through cracks in the tube and likewise through skylights, places where the roof of a tube has fallen in to betrayal the flowing lava. Lava tubes tin exist many meters wide, and typically run several meters below the surface. A broad lava-flow field commonly consists of a chief lava tube and a serial of smaller tubes, which supply lava to the front end of ane or more separate flows. When the supply of lava stops at the end of an eruption or lava is diverted elsewhere, lava in the tube system drains downslope and leaves partially empty conduits below the ground. Inside the tube there can be various formations, similar lava stalactites, known every bit lavacicles. Pillars may stretch from the top to the bottom of the lava tube. Basaltic lava typically produces significant quantities of gas and steam, and while flowing through the tube this causes the air pressure inside to increase. This keeps the tube open merely also may press a hole into the roofing crust, which is still hot and rather soft. Those venting holes are chosen hornitos (Spanish for little ovens) or spatter cones. The gas pressure from beneath throws small-scale pieces of lava out of the venting holes, which form upwardly to 15   m high cones on superlative of the vent. The lava in those cones is formed of layer above layer of spatters (Walker, 1991).

Effigy 15. View of a typical texture produced past a pahoehoe (ropy) lava flow.

The lava will keep to motion and bleed the tube downhill when the volcano spots erupting. This leaves a partially empty tube that is called a lava tube cavern. Lava that is non able to flow out of the tube volition remain in the class of solidified pools, flows, or fifty-fifty congealed, waterfall-similar features. Collapses are rather common, as the roof of lava tubes is rather thin, a event of the mode it formed. As a result most lava tubes do not last more than 10   000 years. Older tubes are extremely rare. I exception, however, is Lava River Cave in Coconino National Forest in Arizona (U.s. Forest Department, 2011). This km-long lava tube cave was formed   ∼   700   ka ago by molten rock that erupted from a volcanic vent in nearby Hart Prairie. Another is Corona lava tube on the Canary Islands (Canaries) that is dated to   ∼   21   ka (Carracedo et al., 2003; Effigy 16 ). In addition to Hawaii, lava tubes besides occur in the western U.S. in Washington, California, Oregon, Nevada, Idaho, New Mexico, Utah, and Arizona, in the Canary Islands, the Galapagos Islands, Italy, Japan, Korea, Kenya, Mexico, and many other volcanic regions (Bunnell, 2008).

Figure sixteen. Tardily Pleistocene Corona lava tube on Lanzarote in the Canary Islands. (a) Opening in the dry section of the lava tube, which stretches for   ∼   viii   km, and (b) interior view of the lava tube.

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LAVA

N. Geshi , in Encyclopedia of Geology, 2005

Lava Tubes

Lava tubes are natural tunnels through which lava travels below the surface of a lava catamenia. Flowing lava is cooled from its surface by radiation and thermal convection of air, and a rigid crust is formed. Once the rigid crust is formed, it provides insulation because of its small thermal conductivity, and the inner molten lava can flow without cooling. In a broad lava-menstruation field, lava tube systems with a master tube from the vent and a series of smaller branches develop, which can supply lava to the forepart of the menstruum without information technology cooling. When the supply of lava ceases at the end of an eruption or the lava is diverted elsewhere, lava in the tube flows out and leaves a partially empty tunnel beneath the ground. Lava tin as well erode downwards, deepening the tube and leaving empty space above the flowing lava, because the walls and floor of the tube consist of lava of the same limerick as the hot lava flowing in the tube, and then the flowing lava tin can cook the wall rock. Lava tubes oftentimes develop in basaltic lava flows with depression viscosity and are rare in highly mucilaginous felsic lava.

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Root Communities in Lava Tubes

Fred D. Stone , ... Manfred Asche , in Encyclopedia of Caves (Second Edition), 2012

Habitat Available for Troglobite Evolution

Lava tubes are a small subset of the total habitat available to troglobites; other habitats include:

•

Mesocaverns, which are minor voids, about 0.v–25   cm in width, beneath the surface in many kinds of substrates. These mesocaverns include fractures, cracks, and vesicles in many kinds of rock; cracks, animal burrows, and tree root holes in soil; spaces between rocks in talus slopes or other types of rock piles; spaces in rocks and gravel from alluvial deposits or along stream beds; and solution cavities. Substrates, in which the mesocaverns are interconnected to course a vast anastomosing organization, can provide ideal habitat for troglobitic species. The mesocavernous environs is most likely the predominant habitat for cave species because information technology has such a large potential area and is near enough to the surface to contain abundant energy resources from root penetration, migrating surface organisms, and water-transported organic matter.

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Caves formed in limestone or other soluble rock are more often than not the all-time studied cave communities because of their attraction to cavers and their accessibility, merely almost, if not all, obligate cave species in caves besides live in the surrounding mesocaverns. Limestone caves may as well contain of import root communities, particularly in areas about the surface or with ready access to the water tabular array.

•

Tree root habitats are far more widespread than those found in lava tubes. Roots can penetrate through soil layers and enter the mesocavernous habitat in many kinds of surface materials. Lava tube root areas are peculiarly important because they allow access to the underground habitat by scientists, who otherwise have a hard time gaining access to the cavern species. Lava tubes have the additional advantage that they form in lava flows that flow forth the surface of the ground, so they generally tend to be fairly shallow throughout their length.

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Ice Caves in the USA

Stephen R. Higham , Arthur N. Palmer , in Ice Caves, 2018

31.9 Hawaii

Hawaii contains many lava tubes, merely most are fairly warm and comprise no ice. The main island is at a latitude of 19 degrees North. All the same, the upper slopes of Mauna Loa, a all the same-active volcano, are at a high enough tiptop (~  3350   grand) that at least two lava tubes containing ice are known on its upper slopes. However, the ice is quickly retreating, according to members of the Hawaii Speleological Guild (Pflitsch et al., 2016). Although the lava tubes were formed by downward-flowing lava, their lower ends are blocked by solidified lava, so the caves human action as cold traps. The largest ice cave contains a frozen lake with a surface area of about 250   mii.

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Caves☆

F.G. Howarth , in Encyclopedia of Ecology (Second Edition), 2013

Succession

Inhabited Hawaiian lava tubes range in historic period from 1 month on Hawai'i Isle to 2.9 one thousand thousand years on O'ahu Island. On Hawai'i Isle colonization and succession of cavern ecosystems can exist observed. Crickets and spiders colonize the surface of new flows within a month of the flow surface cooling. They hibernate in caves and crevices by twenty-four hour period and emerge at night to feed on windborne droppings. Caconemobius rock crickets are restricted to living but in this aeolian (wind-supported) ecosystem and disappear with the institution of plants. The obligate cave species begin to make it within a year after lava stops flowing in the caves. The predatory wolf spider, Lycosa howarthi, arrives first and preys on wayward aeolian arthropods. Other predators and scavenging arthropods – including bullheaded, cave-adjusted Caconemobius crickets – arrive during the adjacent decade. Under rainforest conditions, plants begin to invade the surface later a decade, allowing the root feeding cave animals to colonize the caves. Oliarus planthoppers arrive about 15 years later on the eruption and only v years afterwards its host tree, Metrosideros polymorpha. The cave-adjusted moth, Schrankia howarthi, and the hush-hush tree cricket, Thaumatogryllus cavicola, get in later. The cave species colonize new lava tubes from neighboring older flows via underground cracks and voids in the lava. Caves between 500 and chiliad years erstwhile are most diverse in cavern species. By this time the surface rainforest customs is well-developed and productive, while the lava is all the same young and maximal amount of free energy is sinking hugger-mugger. As soil germination progresses, less water and energy reaches the caves, and the communities slowly starve. In highest rainfall areas, caves support none or just a few species after 10 000 years. Under desert conditions, succession is prolonged for 100 000 years or more. Mesic regimes are intermediate between these two extremes. New lava flows may rejuvenate some buried habitat as well equally create new cave habitat. Thus in volcanic caves, succession proceeds upwards with the younger inhabitable caves occurring above arid remnant older caves. The opposite occurs in limestone where solution and downwards-cutting create younger deeper caves while leaving high and dry remnant passages exposed in cliffs.

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Kazumura Cavern, Hawaii

Kevin Allred , in Encyclopedia of Caves (3rd Edition), 2019

Introduction

Among the many known lava tube caves shortly explored throughout the globe, Kazumura Cavern, on the large isle of Hawaii, stands foremost in length and vertical extent. It is likewise the longest linear cave in the world, extending further over a straight-line distance more than any other. This cave contains a broad range of speleothems and morphology with populations of cave-adapted invertebrates. Considering much of the cave is located under rural subdivisions, it is a popular identify to visit for locals and out-of-state cavers.

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Ice Caves in Norway, Fennoscandia and the Arctic

Stein-Erik Lauritzen , ... Julie Engelien , in Ice Caves, 2018

23.5 Iceland

Among the many (500) lava tubes known in Iceland, only a few are reported to host perennial ice. The two most important ones are Surtshellir and Víðgelmir ( Hróarsson and Jónsson, 1991; Stefansson and Stefansson, 2016), both within the Hallmundahraun lava flow in Western Iceland (Fig. 23.1B). Surtshellir is 3.5   km long. The surrounding lava menstruum is nigh 1100 years erstwhile (Saemundsson, 1966). The inner function of the cavern was depicted in 1835 (Maiers) as having a continuous water ice floor; water ice was also documented by Grossmann and Lomas (1894). Surtshellir and Víðgelmir both have lost a significant amount of ice since the 1970s, and the only lava cave in Iceland with substantial ice formations is Loftshellir (A. Stefansson, p.c., 2017). There is no available information on ice isotopes, chemical science, or age.

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Volcanic Rock Caves

Stephan Kempe , in Encyclopedia of Caves (Second Edition), 2012

Germination of Pyroducts

Even though in many text books lava tunnels are described as having formed by "crusting over of channels" (e.g., Francis, 1993), there is a totally different mechanism by which they can form, and that is by aggrandizement (Hon et al., 1994). This is an incremental process starting at the distal tips of pāhoehoe flows where hot lava rapidly covers the footing in a thin sheet. This sheet cools rapidly, causing the dissolved gases to course vesicles that diminish the overall density of the lava. This sail volition bladder on pinnacle of the next pulse of advancing melt (the lava menstruation is "inflated" from below because of buoyancy) before forming the next distal surface sheet. Multiple advances can occur, forming a primary roof composed of several sheets, separated by sheer interfaces (only the outset or top sheet will display the subaerially formed typical ropy pāhoehoe structure) (Fig. 1). The "oldest" lava sheet is therefore on top of the stack, contradicting normal stratigraphic rules. Below the primary roof the lava can stay hot and can keep flowing. This is the initial conduit. Aggrandizement caves are characterized by roofs congenital of one or several sheets, sometimes more than x continuous sheets of lava. This roof structure tin be studied at roof collapses, called pukas, in Hawai'i. Many of the long Hawai'ian caves are inflationary in origin (Kazumura, Keala, Huehue, Ainahou, Keauhou Trail; just to proper name a few). However, the "crusting-over" of channels can as well lead to long caves. Inspection of cross sections of the roof of the second longest cavern on Hawai'i, the Kipuka Kanohina System (37 km of interconnected passages), has shown that it consists of welded, irregular fragments of pāhoehoe plates, stabilized past inserted lava fingers (squeeze balls) and a 10–l-cm-thick lining welding the roof from below. Such structure suggests that the roof is formed by agglomeration of floating lithoclasts that are wedged into each other similar to a logjam on a river. Sometimes covering-over may also occur by accretion of vertical to subvertical thin lava layers growing from the sides inwards and having a key vertical parting where the growing lateral shelves meet. The levees of open-surfaced lava channels grow by overbank events of sparse lava sheets or by stranded lava floats. Sometimes large sections of the bank break loose and float downstream. These can then jam and form curt roofs that are stabilized past spatter. Examples accept been documented for the channels of the Puhia Pele eruption of 1801 on Hualalai.

Figure 1. Sketch illustrating pyroduct (lava tunnel) formation. At the tip of a pāhoehoe menstruum lava advances quickly in the form of a delta of thin, ropy lava. The side by side pulse of lava lifts the first sheet up (aggrandizement). This procedure is repeated until a stack of lava sheets (the primary roof) is formed, below which the hottest menses thread afterwards becomes the main conduit.

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Recreational Caving

John Yard. Wilson , in Encyclopedia of Caves (Second Edition), 2012

Lava Caves

Lava caves, which are often referred to every bit lava tubes , are the second most common type of cavern used for recreational purposes. Cavers cave in lava tubes also every bit lava voids that are non in tube form. These caves upshot from flowing lava and other processes described elsewhere in this volume. Many lava caves have relatively flat floors and multiple entrances, making them suitable for those with limited caving skills. Lava caves do have their own special risks. They often have dark, very rough-textured surfaces with sharp edges that absorb light, reducing the effectiveness of caving light systems. Many novices have been amazed to discover the extent of torn habiliment after traversing modest passages in lava caves, in contrast to an equivalent-sized passage in a limestone cave.

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