A Field Glossary of Mountain Features

A slender, sharply pointed rock peak. The term is French for 'needle' and is most associated with the Aiguilles around Chamonix. Distinct from a gendarme in that an aiguille is a peak in its own right rather than a tower interrupting a ridge.

A sharp, narrow ridge formed where two glacial cirques erode back-to-back into the same divide, leaving a thin rock crest between them.

A relatively flat step or terrace interrupting an otherwise steep slope. Benches often provide the only viable campsites or rest spots on a long face or ridge.

The crevasse at the head of a glacier where the moving glacier ice pulls away from the stagnant ice and snow frozen to the headwall above. Often the crux obstacle on a face climb.

A prominent rock mass projecting outward from the main face of a mountain, often forming a defined climbing line. A spur is a lesser, narrower version.

A vertical crack or cleft in rock wide enough to admit the climber's whole body, climbed by bracing against opposing walls.

A rock wedged across a crack, chimney, or gully. Can form a useful anchor or an awkward obstacle.

A bowl- or amphitheatre-shaped basin carved by glacial erosion at a valley head, typically with a steep headwall and an over-deepened floor that may hold a tarn.

The low point on a ridge between two peaks, the natural crossing point and often a named mountain pass.

An overhanging ledge of wind-deposited snow projecting beyond a ridge crest on the leeward side. Prone to fracturing back from the lip, a serious hazard to travel along corniced ridges.

A steep, narrow gully channelled into a mountain face, frequently filled with snow or ice and acting as a natural funnel for rockfall and avalanches.

A deep open fracture in a glacier's surface, formed where the ice is stretched as it flows over a steepening or convex bed. Often hidden by snow bridges.

The single hardest move or section of a route or climb, the part that defines its overall difficulty. Knowing where the crux falls shapes how a party paces and protects a pitch.

How serious the consequences of a fall would be (the drop beneath you), independent of how technically hard the moves are. Easy ground can feel intensely exposed above a long drop; this is often what makes a route feel committing.

A large, steep or vertical expanse of mountainside. Usually named by its aspect (the north face, west wall), which governs how much sun, snow and ice it holds and so its condition and difficulty.

A pinnacle or rock tower standing on a ridge crest that blocks the line of travel, forcing a climb over or a traverse around.

A persistent, flowing body of dense ice that deforms under its own weight. It gains mass from snow in the accumulation zone above the equilibrium line and loses it to melt in the ablation zone below, advancing or retreating as that balance shifts.

A glacier clinging to a steep face, perched on a bench or shelf, that periodically calves seracs down the slope below. A serious and unpredictable objective hazard: danger you're exposed to by being beneath it, regardless of skill.

A steep-sided, pyramidal peak produced when three or more cirques erode a single summit from different sides until only a sharp apex remains. The radiating arêtes and multi-sided origin are what distinguish a true horn from an ordinary peak. The Matterhorn is the archetype.

At a smaller scale, any upward-pointing rock protrusion (from a fist-sized nubbin to a larger projection) solid enough to drape a sling over for protection or to grab as a hold. Scale-independent and unrelated to the landform sense; a bollard is the equivalent shaped in snow or ice.

A chaotic, steeply broken section of a glacier where it flows over a cliff or sudden steepening, fracturing into a jumble of seracs and crevasses.

A horizontal break on a steep face, wide enough to stand or belay on. Ledges are the natural rest points, anchor stations, and bivouac spots that break a long climb into pitches.

A compact group of connected heights treated as a single mountain mass, sharing a common base and bounded as one unit even though it carries several distinct summits.

The gap that opens between a snowfield or glacier and the adjacent rock wall, melted out by heat radiating from the sun-warmed rock. Can be deep and awkward to cross where snow meets the base of a face.

Rock debris transported and deposited by a glacier. Lateral moraines ride the glacier's sides; medial moraines form where two glaciers' inner laterals merge; terminal moraines mark the furthest advance at the snout.

Granular snow in transition toward glacial ice. The terms are often used synonymously; where distinguished, névé is young granular snow that has been partly melted and refrozen, and firn is névé that has survived at least one melt season and become denser.

A narrow, sharp cleft in a ridge: in effect a small, abrupt col. Often a key passage point or a place to belay on a ridge traverse.

A tall, slender, isolated rock spire. When a pinnacle sits on a ridge crest and obstructs travel along it, it is usually called a gendarme instead.

A low-angle line of weakness cutting diagonally across an otherwise steep face. Ramps frequently provide the key to an easier passage, linking ledges or letting a party avoid harder direct ground.

Accumulated broken rock on a slope. In geology, scree is the loose material and talus is the landform it builds; among climbers the split is by size: scree is small and loose (you can boot-ski it), talus is blocky (you boulder-hop it).

A large block or column of glacial ice, formed where crevasses intersect or a glacier breaks over a step. Often unstable and liable to collapse without warning.

A smooth, relatively low-angle rock face with few positive holds, climbed largely by friction and balance. Note the clash of senses: in snow, a 'slab' is a cohesive bonded layer that can release as a slab avalanche.

Wind-drifted snow spanning and concealing a crevasse. It may hold a climber's weight or collapse without warning, which is why glacier travel is roped: the central hidden hazard of a snow-covered glacier.

A snowfield is a permanent patch of snow on a slope. To glissade is to descend it deliberately by sliding, on foot or seated, with the ice axe held ready to self-arrest: fast and fun, but dangerous above rocks or runouts.

A subsidiary ridge projecting outward and down from the main mountain mass, essentially a minor buttress. Spurs often provide the natural line of ascent onto a face or ridge.

A summit is the highest point of a mountain; a peak is any prominent high point. Strictly a mountain has one summit but may carry several peaks, a lower one being a subsidiary or secondary peak. Whether a high point ranks as an independent peak comes down to its prominence: how far it rises above the lowest col linking it to higher ground.

A small mountain lake, characteristically occupying the rock basin of a cirque scooped out by glacial erosion.

Moving horizontally across a slope or face rather than directly up or down, to reach a line of weakness, link features, or skirt a hazard. As a noun, a route that crosses a peak or range rather than ascending and descending the same way.

A thin, often nearly invisible film of clear ice glazing rock. Treacherous precisely because the rock looks bare and climbable but offers no grip, a common condition after a freeze following rain or melt.