The rest step is an energy-saving uphill walking technique for steep snow and altitude, where you briefly lock the trailing leg straight and pause on the skeleton between each step, letting the muscles rest for a moment. Combined with rhythmic pressure breathing, it lets mountaineers move steadily for hours without exhausting their legs.
Strap-on (universal) crampons attach with flexible straps and a toe cradle, fitting almost any footwear including flexible boots and even some trail shoes. They are the most versatile and beginner-friendly crampons for glacier travel and general mountaineering, trading some precision and security for broad compatibility.
Postholing is sinking deep into soft snow with each step, leaving holes like postholes, because the snow won't support your weight. It's exhausting and slow, and is the problem snowshoes and skis solve. Snow tends to firm up overnight, so an early alpine start often avoids the postholing that afternoon softening brings.
Talus is an accumulation of large rock blocks at the base of a cliff or steep slope, formed by rockfall. Bigger than scree, talus is crossed by hopping or picking a line between stable blocks. 'Talus hopping' is a common but ankle-testing part of approaching alpine peaks, and shifting blocks demand care.
Scree is an accumulation of small, loose rock fragments on a slope, formed by frost-shattering and erosion. Hikers and mountaineers cross scree on the way to peaks; loose scree can be tiring and treacherous to ascend but is sometimes descended quickly by 'scree skiing'. It contrasts with the larger blocks of talus.
A col is the lowest point on a ridge between two peaks — a mountain pass or saddle. Cols are natural crossing points and route waypoints in mountaineering, often marking the gateway between two valleys or the start of a summit ridge. The term is especially common in alpine climbing.
An ice axe is the fundamental mountaineering tool — a shaft with a pick-and-adze head and a spike at the base — used for balance and support on snow slopes, cutting steps, building anchors, and, crucially, self-arrest to stop a slide. Every snow and glacier mountaineer carries and knows how to use one.
Crampons are metal frames with downward and forward-pointing spikes that strap or clip onto boots to grip snow and ice. They let mountaineers and ice climbers walk and climb on hard, slippery terrain. Designs range from flexible walking crampons to rigid technical models, matched to the boot and the terrain.
A crevasse is a deep crack in a glacier formed as the ice moves over uneven terrain. Crevasses can be tens of metres deep and are often hidden beneath snow bridges, making them one of the principal hazards of glacier travel. Mountaineers rope up and learn crevasse rescue to manage the danger.
Altitude sickness, or acute mountain sickness (AMS), is illness caused by ascending to high altitude faster than the body can acclimatize to the reduced oxygen. Symptoms include headache, nausea, fatigue, and dizziness. It can progress to the life-threatening conditions HAPE and HACE, so the response is to stop ascending and, if it worsens, descend.