A stunning visual tour of the world's most spectacular caves and cave systems.
Caves are found on every continent. The United States is home to the world's longest cave system, the Mammoth Cave in Kentucky, and to the world's most popular tourist cave, New Mexico's Carlsbad Caverns. Great Caves of the World takes readers to these and 25 other astonishing and challenging caves across the globe.
Each entry includes lavish photographs and authoritative text describing the cave, its inhabitants, its environment, how and when it was discovered, access sites, and travel tips on how to get there.
In addition to Carlsbad and Mammoth, featured caves include:
Geologists, expert cavers, spelunkers, climbers, adventure travelers, natural history enthusiasts and general readers will find this book fascinating.
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Tony Waltham is an engineering geologist, karst (limestone cave) specialist and author. He has led caving tours of the United States, Italy, Iceland, Jordan, Syria, Alaska and Russia.Excerpt. © Reprinted by permission. All rights reserved.:
Throughout the world, caves lure cavers and geologists alike to discover how far they extend underground and just how they were formed. The caves described in this book each have some special feature, whether it is their sheer size, their memorable beauty, the mystery of their origins or even the origins of life.
Most caves are formed in limestone, beneath streamless landscapes known as karst. Rainwater slowly dissolves the limestone as it flows down through the bedrock joints. It can create a cave passage wherever it finds a drainage route through a limestone hill, from a Sinkhole or a valley floor through to an outlet at a spring. Water enters a cave through narrow fissures or huge open shafts, and leaves through a resurgence, that is either an open passage or a flooded tunnel beneath a lake surface.
The shapes and profiles of cave passages, and entire cave systems, depend partly on the pattern of joints and bedding planes that the underground drainage originally followed, but more significantly on how the passages were subsequently enlarged. Where a cave passage lies above its resurgence, a stream can freely drain through it. The tumbling and swirling water erodes the cave floor and cuts down into a narrow, twisting, canyon passage, interrupted by waterfall shafts that are enlarged by spray erosion. This is a vadose cave, because it lies above the water table. Below the water table, any passage is totally flooded because its water backs up to its overflow point at the level of the resurgence. As a result, its roof is eroded just as much as its floor, creating a passage with a tubular shape that can extend uphill or downhill because water can flow in any direction under pressure. This is a phreatic cave, meaning that it is full of water -- or was full of water when it was formed. Many vadose streamways end at dark sump pools, where the passages only continue underwater as phreatic tunnels.
Cave passages evolve. Landscapes undergo ceaseless erosion that results in surface lowering. Lower valley floors allow new resurgences to develop, and underground streams find their way down through the rock to create new cave passages at lower levels. High-level caves are then abandoned; whether they were once roaring canyon streamways or silent flooded tubes, they can be left high and dry. These abandoned caves are records of past events, because they show where streams once flowed and at what altitudes valley floors once stood. The caves themselves cannot be dated, but many of their sediments can be, mainly by measuring the ratios of radioactive isotopes in stalagmites and cave sediments. Most caves have developed within the last million or so years, when climates and environments fluctuated through the Ice Ages.
[ Not just limestone and rainwater ] Rainwater alone can dissolve limestone, but it is far more effective after it has passed through a soil layer so that it contains additional carbon dioxide derived from plant decomposition. Most limestone dissolution depends on carbon dioxide, so more plants mean bigger caves -- which is why so many of the world's giant caves lie beneath the forests of the wet tropics. Some very large caves in desert or polar regions are relics from contrasting climates in the past. But others have a completely different origin, some were formed by sulphuric acids rising from deep basins of sedimentary rock. There is still much debate over how some of the world's caves were formed in limestone.
Caves can also form in other rocks, notably gypsum and salt, which are both soluble in water. There are some very extensive gypsum caves scattered around the world, though salt caves are rare because the rock is so soluble that it only survives in dry desert terrains. Caves are also found in lava, where they formed not by any form of erosion but by hot molten rock flowing out of the cores of lava flows.
[ Underground decorations ] The same seeping water that creates caves by dissolving rock may also fill them up by deposition of calcite -- the mineral that comprises both limestone and stalagmites and stalactites. Both processes depend on the levels of carbon dioxide in the rainwater, in the soil and in the cave air. Under the right conditions, water that drips from the cave roof deposits calcite to create the host of decorations that adorn so many cave passages. Stalactites hang from the roof, stalagmites grow up from the floor, and columns are created where the two join. All can be beautifully white, or tinted yellow (mainly by iron oxides). A special type of stalactite is the straw, which has the proportions of a drinking straw and is formed where calcite is deposited just round the rim of water drops that repeatedly hang from its tip. More bizarre is the tiny helictite, which grows in totally random shapes -- upwards, outwards and sideways -- guided by crystal growth within its structure, though there is still some mystery over the causes of their shapes.
A cave stream erodes its floor, but films of water saturated in lime can deposit calcite flowstone on a cave floor. This commonly spreads out from stalagmites and can build up in multiple layers. Rimstone pools, also known as gour pools, lie behind their own calcite dams that have built up by calcite deposition from their thin films of overflow water. Some pools have rimstone dams that grow inwards as shelfstone deposited at the water level, while others have thin, floating rafts of calcite held up by surface tension. Within the pools, calcite may be deposited as rounded masses or as sharp crystals known as dog-tooth spar. As a further variation, drips landing in a shallow pool can disturb the water so that grains on its floor are rolled around, and deposition of the calcite on all sides creates perfectly rounded cave pearls.
Not all decorations are made of calcite. Aragonite has the same chemistry but a different molecular structure, and grows as either sharp and delicate crystals or as tiny branching trees, generally where water evaporates off a calcite surface. Gypsum decorations are formed where sulphate-rich waters seep into limestone caves; their crystals grow from the base, like animal hair, so gypsum flowers form where clusters of crystals curve and splay outwards from a cave wall. Not quite a mineral, ice grows in caves that are cold enough, where both giant frost crystals and dripwater icicles can produce some of the most fantastic cave decorations.
[ Once formed, not forgotten ] Smoothly sculpted and rounded rock walls are the signatures of underground streams that carved caves out of solid rock. But dissolving away the rock is only the start of a cave's history. Roof collapse modifies the profiles of many caves where blocks of rock fall away from unsupported ceilings. Unless removed by a stream, these piles of breakdown can completely block a passage. Collapse cannot form cave chambers on its own, but it modifies their profiles and may cause adjacent cave passages to coalesce into larger voids. Breakdown debris is joined by sand, gravel and mud that are commonly washed into caves. All of these can accumulate in passages, often combining with calcite deposits to partially or totally block them. Many entrances are choked by stream debris, hillside rubble and even glacial debris, so that cavers have to dig a way through before starting their underground explorations.
As an environment for underground life, most caves suffer from a shortage of available food. But a large cave in a tropical climate can house huge colonies of bats that fly out nightly to feed on insects. Bat guano, the droppings beneath their roosts, is the food source for huge assemblages of bugs, beetles, spiders and many more cave-animals. The guano may also be mined to produce fertiliser, but man has long had other uses for caves. Stone Age man lived in the entrance zones, and some ventured further in to paint animal figures on the walls. Some caves have long been holy sites, and others have later been developed as tourist sites. Through all these stages, caves have developed and matured into inn
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Descrizione libro The Natural History Museum, 2008. Condizione libro: Very Good. Ships from the UK. Former Library book. Great condition for a used book! Minimal wear. Codice libro della libreria GRP65511620
Descrizione libro Natural History Museum 01/09/2008, 2008. Hardcover. Condizione libro: Good. Slight tear to the top left corner of the jacket. Some scratches to the jacket. The book is fine to read throughout. Codice libro della libreria 116265-4