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92 pages

English

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A captivating introduction to the world's most fascinating caves, Caves, Revised Edition explores every nook and cranny of these nature-made creations—including lava caves, sea caves, and glacial caves—from Kentucky's Mammoth Cave, to the amazing Paleolithic paintings of Lascaux, to Fingal's Cave of Scotland, which inspired Mendelssohn's Hebrides Overture. Engrossing facts about the geologic origins of these underground voids; their astonishing speleothems, or formations, such as stalactites and stalagmites; and the microscopic extremophile organisms that dwell within are enhanced by exciting photographs and a wealth of other educational resources for further exploration.

Sujets

Science de la Terre

Science

Nature

Formation

Cave

Global

Climate

Geology

Environment

Sciences et techniques

Young Adult Nonfiction

Earth Sicences

Informations

Publié par	Infobase Publishing
Date de parution	01 juin 2019
Nombre de lectures	0
EAN13	9781438182506
Langue	English
Poids de l'ouvrage	1 Mo

Informations légales : prix de location à la page 0,1575€. Cette information est donnée uniquement à titre indicatif conformément à la législation en vigueur.

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Caves, Revised Edition
Copyright © 2019 by Jeanne K. Hanson
All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval systems, without permission in writing from the publisher. For more information, contact:
Chelsea House An imprint of Infobase 132 West 31st Street New York NY 10001
ISBN 978-1-4381-8250-6
You can find Chelsea House on the World Wide Web at http://www.infobase.com
Contents Chapters Caves Mammoth Cave Cenotes, Chicxulub, and the Caves of Yucat n Lascaux Cave Lubang Nasib Bagus and the Sarawak Chamber of Borneo Kazumura Cave Fingal s Cave Waitomo Cave Carlsbad Cavern Wind Cave Kverkfj ll Cave Conclusion: Caves Support Materials Glossary Index
Chapters
Caves

Most of the caves on this planet have not yet been discovered. Geologists estimate that there are literally millions more of them worldwide—and that, even in the United States, we have located only about half of our caves. About 17,000 caves are known to exist already in this country, with about 150 of these open to the public.
It is certain that Mammoth Cave in Kentucky is the prime world-record holder, and it is likely to remain so. With at least 400 miles (650 km) of passageways discovered so far, it is the longest cave in the world. Even readers who have traveled there will be amazed to read about its geology.
Cave superlatives abound—and vary. Lists exist of the longest caves, the caves that reach down to the deepest point, the caves with the deepest single vertical drop (called a pit), the caves with the largest single chambers, the caves with the longest lava tubes created by volcanoes, and more. (No two lists are alike, and even the basic dimensions can differ from source to source.)
These cave records change constantly, for several reasons. New caves are discovered, caves are mapped more fully or with more precise instruments, connections are found that join two known caves, and completely new areas of known caves are found for the first time. In quite a few cases, cavers have come upon vast new sections of known caves by squeezing through passages with names like Gun Barrel, Electric Armpit Crawl, and Devil's Pinch; by scuba diving down to find new openings hidden under the black water; or by improving their equipment and their nerve enough to rappel down a new pit until they hit bottom—and can get back up.
Cave divers are still exploring the often flooded passageways of Sistema Huautla, the deepest cave system in the western hemisphere, located in Oaxaca, Mexico. First discovered in 1966, it is 53 miles (85 km) long, has 25 different entrances, and is 5,118 feet (1,560 m) deep at its lowest point, according to a 2018 National Geographic article.
On the other side of the world, it took nearly 20 years for cave experts to realize that Vietnam's Son Doong cave, found by a local man in 1991, is one of the world's largest caves, big enough to fit 40-story skyscrapers in its huge caverns. Inside the cave is a jungle-like ecosystem, with a river, forests of 100-foot-tall trees, and animals like monkeys, hornbills, and foxes. Scientists are studying its wonders, but there is only one tour company that is allowed to take public visitors into this remarkable cave.
As recently as August 2004, the world record was broken again for the deepest cave pit—a straight-down drop into darkness, with surfaces impossible to climb back up without equipment. Called Velebita Cave, it is in the Velebit Mountains of Croatia, eastern Europe; this new prize-winning plunge is 1,693 feet (516 m) straight down. An impressive vertical drop, this makes that cave deeper, by far, than the Empire State Building is tall. Even with its antenna, the building is "only" 1,454 feet (443 m) tall. And not too far away from this Croatian site is another record-holder, holding firm for now: Krubera Cave (also called Voronya Cave), in the country of Georgia, once part of the Soviet Union. It winds and gradually slopes its way down to the deepest point reached by any cave, 7,188 feet (2,191 m)—more than a mile below the Earth's surface.
It is not a coincidence that these two dramatic record-breaking caves are fairly near each other. It is not a coincidence, either, that the 10 deepest caves are all in Europe while half of the world's longest caves are in the United States (including Mammoth Cave). Geology is the key here.
Cave Sites
Cave science, called speleology, is studied by geologists, chemists (and geochemists), hydrologists, soil scientists, paleontologists, climatologists/meteorologists, extremophile scientists (more on that new science later), and even public health officials. (Some 40 percent of groundwater sources of drinking water in the U.S. comes from karst landscapes where caves are found.) Cave science came into its own in the 17th and 18th centuries and has been growing ever since. There is plenty of room for future scientists to participate.
Recreationists are increasingly discovering caves too—and call them "cavers," not "spelunkers." Anyone can join a local caving club; take a cave walking tour while traveling; do "blackwater rafting," cave swims, and scuba dives; or rappel down cave pits with an organized group. Some cavers are scientists, and many more are devoted amateurs adept at mapping and discovering.
This landform has captured the imagination of people at least as far back as the days of cavemen and cavewomen, who sought shelter in these natural cavities. Native peoples on virtually every continent have used caves for safety, storage, and much else. Religious and artistic experiences have abounded in them for about 30,000 years, as have burials.
In more contemporary times, caves have served as places for small businesses, such as mushroom-growing and night-club management, and larger businesses, such as wineries. Their interiors have featured weddings, television studios, community meetings, light shows, water reservoirs, war defenses, mining, and more. Their unusual environment attracts people.
The darkness and the stable temperature—each cave's temperature hovers around the year average of its aboveground environment—have been found especially pleasant in hot climates. The first "air-conditioned" house in America got that blast of cool because it was built over a cave's mouth. It was in 1901.
Although caves are fairly common, they are also a rare resource in a sense. It takes thousands of years to create even a tiny cave, millions of years to make a big one. (Mammoth Cave required about 2 million years to form.)
Caves do not last forever either. Their roofs often cave in over time, and most of the caves on our planet have been in place for fewer than 10 million years. (This is a far shorter life span than, for example, mountains.) Cave creature species can become extinct easily, too, since the species who live only in caves—and there are thousands of them—do not have a huge population when compared with the average aboveground species. Large-scale churning of the Earth's crust, at least, is only a minor factor in cave destruction. The planet's continental crust is, on average, about 18.6 miles (30 km) thick and does not change much on timescales of less than millions of years.
Types of Caves: Limestone Dissolution
Seven main types of caves exist, as distinguished by the geology of their formation. The first two types to be described below—both variants of the limestone cave—form by the dissolution (dissolving) of this rock. One involves carbonic acid, the other sulfuric acid. These are by far the most common types of cave and usually feature the speleothems one thinks of first in connection with caves (stalactites and stalagmites, for example).
The first and most common type of the limestone dissolution cave forms as a slightly acidic water called carbonic acid erodes the limestone. Mammoth Cave is a superb example. Caves that form in this way can be very deep and contain substantial chambers or rooms. A large limestone cave requires about 1 million years to form, since dissolving solid rock with water is far from instant. Contrary to what many people think, these caves are not formed by a river eating its way through solid rock—the river usually enters the picture later. Instead, water from the surface slowly seeps down, through many tiny but growing cracks in the rock, until it reaches the water table. Limestone rock, unlike many other types of rock, will indeed dissolve in the presence of this seeping, carbonic acid water.
This "cave-making" water derives its acid from natural soils decaying gradually on the surface. And the limestone that receives it came originally from the fossilized bodies of sea animals and sea plants. These marine creatures made their shells and other hard body parts by drawing calcium carbonate out of the ocean water. So the carbonate is present in the limestone rock, ready to be dissolved back out again under the right conditions.
"Limestone caves" are also found in marble, since marble is limestone that had plunged deeper in the Earth and was subjected there to the especially high heat and pressure. This process happens through plate tectonics.
The reason that limestone dissolution caves are so common is because dead-sea creatures are common. Life of this kind began in the sea with a few species a couple of billion years ago and had proliferated vastly by 650 million years ago, well before it existed on land. The skeletal remains of these marine creatures began to accumulate to great thicknesses, without sediments from the continents mixed in to any great degree. The resulting compacted material is called limestone. Over the ages, through plate tectonics, masses of these fossilized sea creatures have been shoved and uplifted onto the land. The oceans have also risen and fallen over the eons, exposing yet more of the limestone.
Limestone