Snow-While certain compacted snow conditions allow mountaineers to progress on foot, typically some form of mechanical device is required to travel efficiently over snow & ice. Snowshoes can be used to walk through deep snow approaching the mountain or on lesser slopes up the mountain. Skis can be used everywhere snowshoes can and also in steeper, more side-hilled landscapes although it takes more practice to develop sufficiently strong skiing skills for difficult terrain. Skis can also be a form of the sport by itself, called Ski Mountaineering. Crampons may be used on hard snow (neve) and ice to provide additional traction & allow very steep ascents.
Glaciers-When traveling over glaciers, crevasses pose a grave danger. These giant cracks in the ice are not always visible as snow can be blown and freeze over the top to make a snowbridge. At times snowbridges can be as thin as a few inches. Climbers use a system of ropes to protect themselves from such hazards. Basic gear for glacier travel includes crampons and ice axes. Teams of two to five climbers tie into a rope equally spaced. If a climber begins to fall the other members of the team perform a self-arrest to stop the fall. The other members of the team enact a crevasse rescue to pull the fallen climber from the crevasse.
Here’s just the tip of the iceberg, about the dangers of mountaineering:
The places where ice may fall can always be determined beforehand. It falls in the broken parts of glaciers (seracs) and from overhanging cornices formed on the crests of narrow ridges. Large icicles are often formed on steep rock faces, and these fall frequently in fine weather following cold and stormy days. They have to be avoided like falling stones. Seracs are slow in formation, and slow in arriving (by glacier motion) at a condition of unstable equilibrium. They generally fall in or just after the hottest part of the day, and their debris seldom goes far. A skillful and experienced ice-man will usually devise a safe route through a most intricate ice-fall, but such places should be avoided in the afternoon of a hot day. Hanging glaciers (i.e. glaciers perched on steep slopes) often discharge themselves over steep rock-faces, the snout breaking off at intervals. They can always be detected by their debris below. Their track should be avoided.