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 snow bridge is a span of snow that forms over a crevasse, sometimes hiding it completely. Snow bridges can be strong enough to cross or thin enough to collapse under a climber, which is why glacier travelers rope up, probe suspect bridges, and cross them carefully or avoid them.
A cornice is an overhanging lip of wind-blown snow that builds out horizontally from a ridge crest, like a frozen wave. Cornices can collapse under a climber's weight or break off naturally, so mountaineers stay well back from the edge and treat the slope below as avalanche-prone.
A couloir is a steep, narrow gully on a mountainside, often filled with snow or ice, that provides a natural line of ascent or descent. Couloirs are classic alpine and ski-mountaineering routes, but they channel rockfall, avalanches, and meltwater, so timing and hazard awareness are critical.
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.
Mountaineering boots are stiff, insulated, crampon-compatible boots built for snow, ice, and high-altitude climbing. Their rigid soles support precise cramponing and kicking steps, while insulation — and on the warmest models, double-boot construction — protects against frostbite. They're categorized by stiffness and warmth to match the objective.
A roped team is a group of mountaineers tied together on a single rope for mutual protection, most commonly during glacier travel, where the team can arrest and rescue a member who falls into a crevasse. Members travel at set spacing with the rope managed to minimize slack, ready to react instantly to a fall.
A bergschrund is the crevasse that forms at the head of a glacier where the moving glacial ice pulls away from the stationary ice or rock above. Often deep and bridged by snow, the bergschrund is a classic obstacle and crux at the start of many alpine climbs, sometimes requiring a tricky crossing.
A serac is a large block or pinnacle of glacial ice, formed where a glacier breaks up over steep or uneven ground. Seracs can topple without warning, making serac fall one of the deadliest objective hazards in mountaineering. Climbers minimize the time they spend beneath them.