Devoir de Philosophie

Mountain Climbing.

Publié le 14/05/2013

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Mountain Climbing. I INTRODUCTION Mountain Climbing, ascending mountains, most commonly as a recreational activity. Mountain climbing is popular worldwide, wherever hills rise high enough to provide challenge. The activity's rewards include the physical exertion it requires, the satisfaction of overcoming difficulties by working with others, the thrill of reaching a summit, and the unobstructed view from a mountaintop. Exploration and research are other reasons that people climb mountains. Ascents can be either nontechnical (a hike up a path or a scramble over rocks, not requiring the safety of a rope), or technical (a climb up more difficult terrain that requires the use of rope and other specialized equipment). This article focuses on technical climbs, which involve all the elements of simple hikes but also require advanced knowledge and equipment. Making technical climbs is also known as mountaineering. Since ancient times, people have viewed mountain peaks as towering objects of myth, spiritual inspiration, and romantic beauty. Early peoples made ascents only to hunt game, to rescue lost or strayed animals, or to gain a military advantage over an enemy. Eventually, the unknown and inaccessible ceased to be something to be feared and avoided, and the conquest of the major mountain peaks and ranges of the world began. Mountaineering as a sport was born on August 8, 1786, with the first ascent of Mont Blanc (4,810 m/15,782 ft), one of Europe's tallest peaks. Since that ascent, mountain climbing has evolved into three related sports: alpine climbing, ice climbing, and rock climbing. These sports require the same fundamental techniques. II CLIMBING FUNDAMENTALS Experienced climbers prepare for a climb by buying a topographical map and a regional guidebook with charts of the expected terrain and descriptions of the mountain's approach trails. Climbers begin major ascents by hiking to the base of the mountain, where they set up an overnight camping spot, known as a base camp. Early the next morning, they begin their ascent. On climbs that last only one day, experienced climbers attempt to reach the summit by noon, before afternoon thunderstorms, lightning, hail, and rain increase the danger of the climb. Climbers also make sure they have enough daylight to rappel (slide in a controlled fashion down climbing ropes) back to the mountain's base and reach base camp before dark. On rare occasions climbers are caught in the dark and must resort to headlamps or flashlights to find their way back to camp. On ascents that last more than one day, an early start gives climbers enough time to set up their next camp on the mountain before nightfall. If there is snow on the route, starting early means that the frozen surface will not melt before the climbers cross it. Because mountain climbers surmount dangerous terrain by using ropes and other equipment, they almost always climb in teams. The basic team is composed of two people, the leader and the second. Each has one end of the climbing rope tied into his or her climbing harness, a device that secures the climber to the rope in case of a slip. The leader's job is to lead the climb by following a natural line or path to each successive ledge or resting spot. The leader also places climbing equipment known as hardware in cracks, snow, and ice at various points along the ascent. When attached to the climbing rope, the hardware becomes a series of anchors that hold a climber in the event of a fall. The second feeds out rope as the leader progresses upwards. Paying out the rope (or conversely, pulling it in) is called belaying. The second also passes the rope around his or her waist or through a friction device that attaches to the climbing harness. Should the leader fall, the second can hold tightly to the rope, which creates enough friction to stop the rope's movement and break the leader's fall. After the leader reaches a ledge and secures several pieces of hardware for a belay anchor, the second begins climbing, following the leader's route and gathering the hardware. When the second reaches the leader, the team rests and then proceeds by climbing another rope length, or pitch. Because leading is stressful and tiring, the leader and the second sometimes switch positions, a process called swinging leads. III ALPINE CLIMBING The style of mountaineering under which these basic climbing techniques developed is called alpinism, or alpine climbing, and this style encompasses much of the equipment, technique, and safety precautions that form the basis for ice climbing and rock climbing. Alpine climbing began in the European Alps in the late 18th century and is now practiced in all mountain ranges of the world. The most popular alpine climbing areas in the United States are the Colorado Rocky Mountains, the Sierra Nevada range in California, the Cascade Range of the northwestern United States and southwestern Canada, and the Alaska Range in the vicinity of Mount McKinley (6,194 m/20,320 ft). Alpine climbing involves the continuous ascent of a mountain peak over a period of one to several days by a team of at least two alpinists. Teams may consist of as many as four climbers. The climbers carry all the equipment they need--a camping stove and fuel, sleeping bags, sleeping mats, a tent or bivouac sack, first aid gear, a water bottle, and food. Each night the climbers bivouac, or spend the night on a mountain ledge, before continuing upward. A Equipment Alpine climbers try to stay warm and dry, so proper clothing is essential. They avoid using cotton clothing because once wet, it conducts heat away from the body. Instead, many mountaineers use synthetic underwear; fleece hats, jackets, and pants; and jackets and snow pants made of waterproof, breathable material such as Gore-Tex. These types of clothing allow sweat and water vapor to escape from the skin through the clothing. By keeping warm and dry, mountaineers avoid the dangers of severely chilling their body core, which can lead to hypothermia. For more information on hypothermia and other hazards associated with mountain climbing, see the Mountain Safety section of this article. Preferred mountaineering footwear is either heavy-duty, stiff-soled boots made of leather or synthetic material, or lightweight plastic boots that are completely waterproof. Mountaineers wear fiberglass or high-strength plastic helmets to protect their heads from falling pieces of rock or ice, as well as from head injuries if they fall themselves. Mountain climbers use many different tools. The most basic of these are climbing harnesses, climbing ropes, ice axes, and crampons. Climbers also use a variety of types of hardware to anchor themselves to the mountainside. A climbing harness is an adjustable set of straps that buckle around the waist and thighs of a climber. Most harnesses also come with special, easy-to-reach loops for attaching hardware and other climbing tools. The harness serves as an anchor for one end of the climbing rope. In the event of a fall, the anchors set in the mountainside halt the fall, and the harness holds the climber tight but does not restrict movement or breathing. Climbing ropes are specially made lines of a high-strength nylon called Perlon. Ropes that measure 50 m (164 ft) in length and 10.5 mm (2/5 in) in diameter are standard for rock climbing. Ropes 60 m (197 ft) in length and 9 mm (1/3 in) in diameter are preferred for alpine and ice climbing; these ropes are usually waterproof, or everdry, so that they will not freeze and become stiff in cold or wet conditions. Ice axes have either a metal or fiberglass shaft. One end of the shaft is a pointed metal spike. The other end is topped with a head that has a metal pick with serrated teeth on one side, and a straight, flat, metal blade called an adze on the other. Ice axes have many uses. One of the most common is to help the climber stay balanced on steep slopes. The climber swings the axe with a short, quick movement to lodge the pick in snow or ice, creating a secure anchor. If a climber should slip and begin sliding down a snowfield, a self-arrest can be performed by turning face down on the snow and burying the pick in the snow surface. The climber's weight over the pick and firm grip on the ice axe usually stop any downward movement. Mountaineers also use the axe to chop steps in snow or ice. Longer axes are used as walking sticks and for probing crevasses during glacier travel. Alpine climbers gain a foothold on steep and snowy slopes by using crampons. Invented in 1908 by British climber Oscar Eckenstein, crampons are frameworks of sharp metal teeth that fasten to mountaineering boots and grip the snow and ice. They attach to the boots with straps that lace around the ankles or by snaps that connect to the boot sole. Basic mountaineering crampons are hinged between the sole and the heel, have straps, and have 10 or 12 points. More technical crampons have two teeth pointing forward. These teeth, called front points, allow a climber to kick straight into the ice or snow on especially steep slopes. When attached to a climber's rope, hardware provides anchors to steep slopes. Hardware can include such items as nuts and chocks, which are wedge-shaped or hexagonal pieces of aluminum alloy attached to a wire cable or a Perlon sling. Climbers can wedge these high-strength pieces of metal into cracks and fissures in the rock. Hardware also includes spring-loaded camming devices that wedge into cracks in the rock. These range in size from 1 to 15 cm (.5 to 6 in) wide. Other types of hardware include ice screws, which are threaded, aluminum alloy tubes with sharp teeth that are screwed directly into ice; and snow pickets, lightweight metal stakes that climbers hammer into the snow. In the eye (or hole) at the end of each of these devices the climber clips in a carabiner, an oval-shaped, spring-loaded metal link. The link attaches to a short length of nylon webbing and another carabiner, through which the climbing rope attaches. Should the climber slip, this series of anchors, carabiners, and webbing acts as a shock absorber. It distributes the pressure of the fall to each of the climber's anchors and reduces the risk of a long and dangerous drop. All mountaineers also carry several other items: a compass; topographic maps that indicate elevations, place names, and geographical formations in the area; and an altimeter, which calculates altitude above sea level. Altimeters, which work on barometric principles, can also be used to anticipate weather changes. B Mountain Safety An accident while mountain climbing generally has unexpected and negative consequences. A seemingly small mistake, such as twisting an ankle in loose rocks, can quickly turn into a dangerous situation if the climber is on difficult terrain and is still some distance from the base camp. Climbers can minimize the consequences of these mistakes by traveling in groups, carrying first aid equipment, and being cautious in their route planning. Alpine climbers are also exposed to perils beyond their control, such as hidden crevasses and avalanches, and because of the inhospitable environment of most mountains, they risk exposing themselves to hypothermia and altitude sickness. Experienced mountaineers plan ahead for all contingencies and let others know their destination and planned return time. Crevasses are deep ice fissures or large cracks within a glacier. Many times crevasses are hidden under a covering of snow, making them difficult to identify. Their steep, slippery sides make them almost impossible to climb out of without assistance. For this reason, climbers often rope together and secure themselves to each other when traveling on glaciers and snowfields. Should one partner fall in a crevasse, the other can break the fall and then pull their partner out. Avalanches are sudden flows of a large mass of snow or ice down a slope or cliff, sometimes at speeds exceeding 160 km/h (100 mph). They occur when heavy snowfall accumulates on steep slopes and the underlying snow pack cannot support the new snow's weight. Mountaineers can minimize avalanche dangers by staying aware of rapid changes of weather, especially increases in temperature and wind. They should also avoid steep, narrow chutes that provide ideal channels for avalanches. Hypothermia occurs when the body becomes too chilled to generate enough warmth for vital organs such as the heart and lungs. Most climbers understand that hypothermia is a danger during extremely cold weather, but it also can occur when temperatures are well above freezing. In fact, most cases occur when the outside temperature is from 7° to 10°C (45° to 50°F). Avoiding hypothermia requires several simple precautions. Mountain climbers should stay dry and avoid cotton clothing, which dries slowly and sucks away body warmth as it does dry. They should eat, drink water, and rest frequently, helping them maintain energy levels. Altitude sickness, also known as mountain sickness, is caused by insufficient oxygen at high elevations. It causes dizziness, shortness of breath, and confusion, and it can strike climbers at any elevation above 2,400 m (about 8,000 ft). Mountaineers who ascend to higher altitudes often take a day or two to become accustomed to their new environment. They climb slowly when going above 4,500 m (15,000 ft). If climbers develop symptoms of altitude sickness, they should descend immediately to a lower altitude before the condition worsens. Some climbers use bottled oxygen to combat the effects of the sickness and aid their efforts at higher altitudes. C Conditioning and Learning to Climb Mountaineers need to be in excellent physical shape, and many people train for mountain climbing by running, hiking, and bicycling. While climbing, mountaineers must remain relaxed and focused in tense situations, such as when they are having trouble picking the correct route up or down a mountain, when a storm is approaching, or when night is falling. Traditionally, beginning mountaineers learned safe climbing skills through a mountain apprenticeship. Older, more experienced climbers and guides accompanied beginners on a number of ascents and acted as mentors, demonstrating techniques and providing encouragement. Today, beginners can follow the apprenticeship route or learn these skills from a qualified friend or from climbing schools or guide services that are certified by such organizations as the American Mountain Guides Association (AMGA). IV ICE CLIMBING Ice climbing grew out of traditional mountaineering, and ice climbers use the basic equipment, techniques, and safety precautions that alpinists do, with certain specialized changes to account for the added difficulties of ascending vertical sheets of ice. In 1932 French climber Laurent Grivel added two extra front points to Eckenstein's ten-point crampons. This enabled mountaineers to ascend more difficult and steeper climbs over icy routes. In the early 1970s American mountaineer and inventor Yvon Chouinard designed curved ice axe picks, which made it easier to drive axes into ice and secure them there. Ice climbers later created more radically drooped ice axe picks and ergonomically designed ice axe shafts, allowing them to venture onto continuously vertical, and even overhanging, frozen waterfalls. A Forms of Ice Climbers encounter two natural forms of ice: alpine ice and water ice. Mountaineers and alpinists look out for alpine ice, while ice climbers deliberately search for water ice. Alpine ice is composed of large sheets of snow on mountainsides that over time have melted and refrozen. Water ice occurs at lower altitudes on frozen waterfalls, where it can take the shape of toothy icicles, steep curtains and pillars, free-standing columns, and thin veneers over rock. Whereas some alpine climbers regard ice as an obstacle to be overcome in the course of making a longer ascent, ice climbers seek out ice to pit themselves against its verticality and physical difficulty. Ice climbs are therefore shorter than alpine ascents, but they can be more taxing. B Ice Climbing Equipment and Technique Ice climbers use an array of sharply pointed tools, notably 12-point rigid-frame crampons, two ice axes, and ice screws. An ice climber begins an ascent by kicking and securing the front points of each crampon in the ice. The climber then centers his or her body weight over the front points and concentrates on securing the ice axes. The climber swings one axe overhead and lodges it firmly into the ice, then does the same with the other. Then the climber pulls up and resecures the crampons slightly higher. The climber repeats this technique over and over, moving higher with each step. To protect against falls, ice climbers anchor an ice screw every 5 to 10 m (16 to 33 ft), attaching their rope to the ice screw. They hand-screw the ice screws or twist them in using an axe pick. The ice screw anchors and the rope work together to reduce the danger of falls. For safety, climbers try to avoid breaking off large pieces of brittle ice with the ice axe. These ice chunks and shards can be sharp and can cause injuries. V ROCK CLIMBING As alpine climbing developed in the European Alps in the early 20th century, French and German mountaineers sought out new challenges by training on cliffs and boulders near their homes. The earliest documented rock climb done for sport (not for military reconnaissance or scientific inquiry) was the 35-m (115-ft) high Nape's Needle in the Lake District of England, which W. P. Hasket-Smith climbed alone on June 27, 1886. The first documented rock climb in North America was made in 1910 on a portion of Mount Washington in the White Mountains of New Hampshire, although the mountain itself had been climbed much earlier. Rock climbing is now practiced on cliffs with a wide range of heights. Areas may be relatively small crags of rock, large canyon sidewalls, or immense mountain faces. Granite, limestone, sandstone, metamorphosed schist, and gneiss are the five most popular rock types for climbing. A Rock Climbing Technique Rock climbers train by bouldering, which means practicing difficult climbing moves on large boulders or small outcroppings of rock that are only several feet above the ground. Bouldering is relatively safe because climbers can jump back onto solid ground at any moment. Difficult and strenuous movements can therefore be rehearsed without the use of ropes and hardware. When ascending cliffs that are less than 50 m (164 ft) high, climbers use a technique called top-roping. On a top-rope belay, the climber is anchored from above, so he or she is protected against a serious fall. Rock climbers generally use a standard 50-m or 60-m rope. Rock climbs higher than 60 m thus require more than one pitch, or rope length, to be scaled; this type of climbing is termed multipitch or continuous climbing. Specific types of rock climbing movements include friction climbing (moving up smooth, relatively low-angled rock slabs); face climbing (holding onto flakes, knobs and edges to ascend a sheer wall); crack climbing (jamming fingers, hands, arms, legs, feet, and toes into fissures in the rock); and overhang climbing (expending quick, calculated bursts of energy and muscle to swing past overhangs). Strength is a major aspect of rock climbing, but it is not the most important physical requirement. Experienced climbers focus more on endurance, muscle coordination, flexibility, finesse, and excellent balance. On vertical and overhanging cliffs, moving smoothly up the rock, staying relaxed, and being mentally confident are equally vital to success. There are two main types of rock climbing: free climbing and aid climbing. In its most basic form, a free climb is the unsupported ascent of a cliff face. Climbers use their fingers to grip flakes, edges, and cracks in the surface, while sticky rubber-soled shoes give support. The climber employs rope or other forms of protection, but only as a precaution to prevent a serious fall. The pieces of protection are never used to rest on, or for advancement. As soon as a climber uses equipment for support, he or she is no longer free climbing. The climber will then descend again to the last resting point where no support was used and reclimb the problematic section. In aid climbing (also known as artificial climbing), climbers ascend pitches while using rope and hardware to support their body weight. Aid climbers also use a number of tools, including pulleys to move gear up the rock wall and étriers, or slings, to rest in. On climbs that require two or more days, climbers also use a portaledge. This easy-to-assemble device made of poles and shock-cords forms a rigid nylon floor and waterproof tent. The portaledge hangs from anchors placed in the rock wall and enables climbers to sleep and rest in a comfortable position, even though they may be hundreds or thousands of feet off the ground. Rock climbing routes are named and assigned a difficulty rating by the first team of climbers to ascend a particular route. In the United States, free climbs are graded using decimal ratings, which range from 5.0 (easiest) to 5.14 (most difficult). In guidebooks the climb's name is also accompanied by a commitment rating, which indicates the climb's seriousness and how many hours or days it will take a team of two average-ability climbers to complete the route. Commitment ratings are given in Roman numerals from I (several hours) to VI (difficult climbs in remote locations). A similar scale (A1 to A5) is used when evaluating aid-climbing routes. B Rock Climbing Equipment Rock climbing shoes resemble toughened ballet slippers, made of supple leather or synthetic materials. They have sticky rubber soles, and toes and heel-liners made of rubber. All climbing shoes and slippers should be fitted snugly around the foot. Climbers use gymnastic chalk (magnesium carbonate) to dry sweat from their hands and fingers while climbing. The white powder is carried in a small pouch called a chalk bag that is attached to the climber's harness. Because rock climbing requires plenty of innovative, supple movements, clothing should be lightweight, comfortable, and nonrestricting. T-shirts, shorts, and tights made of cotton, Lycra-cotton blends, and other synthetic materials are popular. Rock climbers also use athletic tape to protect fingers, knuckles, and wrists during difficult climbs. VI HISTORY People have long climbed mountains for necessary daily activities such as retrieving lost animals and hunting, but technical climbing as a sport has a much shorter history. The sport's history is often described in terms of first ascents, the conquering of previously unscaled mountains or, on mountains that have already been climbed, the accomplishment of previously untried and unclimbed routes. After the ascent of Mont Blanc in 1786, people began to organize expeditions to make first ascents. Some of the most challenging mountains were found in the Himalayas of Central Asia, which contain many of the world's highest peaks. In 1953 New Zealand climber Sir Edmund Hillary and Sherpa Tenzing Norgay made the first ascent of the world's highest mountain, the Himalayan peak Mount Everest (8,850 m/29,035 ft). A year later Italian mountaineers Achille Compagnoni and Lino Lacedelli ascended the world's second highest mountain, K2 (8,611 m/28,251 ft), which is also in the Himalayas. As more of the world's mountains were climbed for the first time, mountaineers sought to challenge themselves by using more difficult routes and by climbing with less assistance from climbing partners. In 1978 Italian mountaineer Reinhold Messner and Austrian climber Peter Habeler became the first to scale Everest without bottled oxygen. Two years later Messner returned to climb Everest completely alone and without oxygen. Ascents in the late 20th and early 21st century became even more daring, and some climbers attempted to surmount groups of related summits. In 1985 American climber Dick Bass became the first mountaineer to climb the highest mountain on each of the seven continents, collectively referred to as the Seven Summits. In 1986 Messner finally completed his goal of climbing the 14 highest mountains in the world--a feat that took him 17 years to accomplish. All are higher than 8,000 m (26,000 ft) and are located in Nepal, Pakistan, China, and Tibet. Ed Viesturs became the first U.S.-born climber to accomplish this feat when he reached the summit of Annap? rna in May 2005. All of Viesturs's 14 climbs, made over a period of 16 years, were completed without the benefit of bottled oxygen. VII RECENT DEVELOPMENTS In recent years, well-publicized successes and tragedies in mountaineering activities, and improvements in climbing equipment, have given rise to an increased number of mountain climbers worldwide. The sport's popularity has led some countries to require mountaineers to purchase climbing permits. Himalayan expeditions must also pay an environmental bond to guarantee that they will remove all of their waste at the conclusion of their trip. Environmental efforts are underway at many rock climbing areas, where local climbers participate in an annual cleanup day to maintain approach trails, wash gymnastic chalk off the rock, and pick up litter. In the United States, placement of equipment that damages the rock is regulated on state and federal lands. The Access Fund is the national organization that helps climbers gain access to climbing areas and also assists with environmental problems associated with cliffs in the United States. Beginning in the 1980s indoor rock-climbing gyms have played a key role in introducing large numbers of people to climbing, featuring short climbs in a controlled setting. However, making the transition to climbing outside is not always easy. New skills and judgment calls are required outdoors, because real cliffs are subject to bad weather and other hazards such as loose rock and falling stones. In the late 20th century, climbing competitions became popular with rock climbers and ice climbers of all ages and skill levels. Regular competition climbing is judged on how high the climber can ascend within a specified period of time. Speed climbing competitions pit climbers against a clock to see how fast they can scale a wall. Local climbing gyms and clubs sponsor competitions, as do national organizations such as the American Sport Climbing Federation. Internationally, mountaineers, ice climbers, and rock climbers are represented by the Union Internationale des Associations d'Alpinisme (UIAA). Since its founding in 1932, the UIAA has grown to represent about 80 associations in about 60 countries. As mountain climbing's popularity rose dramatically in the 1980s and 1990s, the UIAA's role in mountain safety, education, and environmental policy also increased. In the United States, the American Alpine Club, the Appalachian Mountain Club, the Colorado Mountain Club, and the Sierra Club are only a few of the organizations that have also addressed these issues. These organizations also offer instructional programs in climbing and provide an opportunity to meet fellow enthusiasts. Contributed By: Ed Webster Reviewed By: Nick O'Connell Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.

« teeth on one side, and a straight, flat, metal blade called an adze on the other.

Ice axes have many uses.

One of the most common is to help the climber stay balanced on steep slopes.

The climber swings the axe with a short, quick movement to lodge the pick in snow or ice, creating a secure anchor.

If a climber should slip and beginsliding down a snowfield, a self-arrest can be performed by turning face down on the snow and burying the pick in the snow surface.

The climber’s weight over the pick and firm grip on the ice axe usually stop any downward movement.

Mountaineers also use the axe to chop steps in snow or ice.

Longer axes are used as walking sticksand for probing crevasses during glacier travel. Alpine climbers gain a foothold on steep and snowy slopes by using crampons.

Invented in 1908 by British climber Oscar Eckenstein, crampons are frameworks of sharpmetal teeth that fasten to mountaineering boots and grip the snow and ice.

They attach to the boots with straps that lace around the ankles or by snaps that connect tothe boot sole.

Basic mountaineering crampons are hinged between the sole and the heel, have straps, and have 10 or 12 points.

More technical crampons have twoteeth pointing forward.

These teeth, called front points, allow a climber to kick straight into the ice or snow on especially steep slopes. When attached to a climber’s rope, hardware provides anchors to steep slopes.

Hardware can include such items as nuts and chocks, which are wedge-shaped or hexagonal pieces of aluminum alloy attached to a wire cable or a Perlon sling.

Climbers can wedge these high-strength pieces of metal into cracks and fissures in therock.

Hardware also includes spring-loaded camming devices that wedge into cracks in the rock.

These range in size from 1 to 15 cm (.5 to 6 in) wide.

Other types ofhardware include ice screws, which are threaded, aluminum alloy tubes with sharp teeth that are screwed directly into ice; and snow pickets, lightweight metal stakes that climbers hammer into the snow. In the eye (or hole) at the end of each of these devices the climber clips in a carabiner, an oval-shaped, spring-loaded metal link.

The link attaches to a short length of nylon webbing and another carabiner, through which the climbing rope attaches.

Should the climber slip, this series of anchors, carabiners, and webbing acts as a shockabsorber.

It distributes the pressure of the fall to each of the climber’s anchors and reduces the risk of a long and dangerous drop. All mountaineers also carry several other items: a compass; topographic maps that indicate elevations, place names, and geographical formations in the area; and analtimeter, which calculates altitude above sea level.

Altimeters, which work on barometric principles, can also be used to anticipate weather changes. B Mountain Safety An accident while mountain climbing generally has unexpected and negative consequences.

A seemingly small mistake, such as twisting an ankle in loose rocks, canquickly turn into a dangerous situation if the climber is on difficult terrain and is still some distance from the base camp.

Climbers can minimize the consequences ofthese mistakes by traveling in groups, carrying first aid equipment, and being cautious in their route planning.

Alpine climbers are also exposed to perils beyond theircontrol, such as hidden crevasses and avalanches, and because of the inhospitable environment of most mountains, they risk exposing themselves to hypothermia andaltitude sickness.

Experienced mountaineers plan ahead for all contingencies and let others know their destination and planned return time. Crevasses are deep ice fissures or large cracks within a glacier.

Many times crevasses are hidden under a covering of snow, making them difficult to identify.

Theirsteep, slippery sides make them almost impossible to climb out of without assistance.

For this reason, climbers often rope together and secure themselves to each otherwhen traveling on glaciers and snowfields.

Should one partner fall in a crevasse, the other can break the fall and then pull their partner out. Avalanches are sudden flows of a large mass of snow or ice down a slope or cliff, sometimes at speeds exceeding 160 km/h (100 mph).

They occur when heavy snowfallaccumulates on steep slopes and the underlying snow pack cannot support the new snow’s weight.

Mountaineers can minimize avalanche dangers by staying aware ofrapid changes of weather, especially increases in temperature and wind.

They should also avoid steep, narrow chutes that provide ideal channels for avalanches. Hypothermia occurs when the body becomes too chilled to generate enough warmth for vital organs such as the heart and lungs.

Most climbers understand thathypothermia is a danger during extremely cold weather, but it also can occur when temperatures are well above freezing.

In fact, most cases occur when the outsidetemperature is from 7° to 10°C (45° to 50°F).

Avoiding hypothermia requires several simple precautions.

Mountain climbers should stay dry and avoid cotton clothing,which dries slowly and sucks away body warmth as it does dry.

They should eat, drink water, and rest frequently, helping them maintain energy levels. Altitude sickness, also known as mountain sickness, is caused by insufficient oxygen at high elevations.

It causes dizziness, shortness of breath, and confusion, and itcan strike climbers at any elevation above 2,400 m (about 8,000 ft).

Mountaineers who ascend to higher altitudes often take a day or two to become accustomed totheir new environment.

They climb slowly when going above 4,500 m (15,000 ft).

If climbers develop symptoms of altitude sickness, they should descend immediatelyto a lower altitude before the condition worsens.

Some climbers use bottled oxygen to combat the effects of the sickness and aid their efforts at higher altitudes. C Conditioning and Learning to Climb Mountaineers need to be in excellent physical shape, and many people train for mountain climbing by running, hiking, and bicycling.

While climbing, mountaineers mustremain relaxed and focused in tense situations, such as when they are having trouble picking the correct route up or down a mountain, when a storm is approaching, orwhen night is falling. Traditionally, beginning mountaineers learned safe climbing skills through a mountain apprenticeship.

Older, more experienced climbers and guides accompaniedbeginners on a number of ascents and acted as mentors, demonstrating techniques and providing encouragement.

Today, beginners can follow the apprenticeship routeor learn these skills from a qualified friend or from climbing schools or guide services that are certified by such organizations as the American Mountain GuidesAssociation (AMGA). IV ICE CLIMBING Ice climbing grew out of traditional mountaineering, and ice climbers use the basic equipment, techniques, and safety precautions that alpinists do, with certainspecialized changes to account for the added difficulties of ascending vertical sheets of ice.

In 1932 French climber Laurent Grivel added two extra front points toEckenstein’s ten-point crampons.

This enabled mountaineers to ascend more difficult and steeper climbs over icy routes.

In the early 1970s American mountaineer andinventor Yvon Chouinard designed curved ice axe picks, which made it easier to drive axes into ice and secure them there.

Ice climbers later created more radicallydrooped ice axe picks and ergonomically designed ice axe shafts, allowing them to venture onto continuously vertical, and even overhanging, frozen waterfalls. A Forms of Ice Climbers encounter two natural forms of ice: alpine ice and water ice. Mountaineers and alpinists look out for alpine ice, while ice climbers deliberately search for water ice.

Alpine ice is composed of large sheets of snow on mountainsides that over time have melted and refrozen.

Water ice occurs at lower altitudes on frozen waterfalls,where it can take the shape of toothy icicles, steep curtains and pillars, free-standing columns, and thin veneers over rock.

Whereas some alpine climbers regard ice asan obstacle to be overcome in the course of making a longer ascent, ice climbers seek out ice to pit themselves against its verticality and physical difficulty.

Ice climbsare therefore shorter than alpine ascents, but they can be more taxing.. »

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