libterm.com A crevasse is a deep, open crack found in glaciers or ice sheets, formed by the movement and stress of the ice as it flows. These fissures vary in size and depth and pose significant dangers to climbers and explorers traveling across icy terrains. Discover more about the formation, risks, and safety measures related to crevasses in the rest of this article.
Table of Comparison
| Feature | Crevasse | Bergschrund |
|---|---|---|
| Definition | A deep crack or fracture in a glacier or ice sheet. | A large crevasse that forms between moving glacier ice and stationary ice or rock. |
| Formation | Caused by stress from glacier movement over uneven terrain. | Forms where the glacier ice separates from the stagnant ice or firn above. |
| Location on Glacier | Anywhere along the glacier surface, often in zones of tension. | Typically near the glacier head, at the upper boundary between moving and stationary ice. |
| Size & Depth | Varies widely, from small cracks to several meters wide and deep. | Usually larger and wider; can be tens of meters wide and deep. |
| Significance | Indicates glacier movement and stress patterns; hazard for climbers. | Marks the boundary of glacier movement; critical in analyzing glacier dynamics. |
Understanding Crevasse and Bergschrund: Key Definitions
A crevasse is a deep, open crack in a glacier or ice sheet caused by stress and deformation as the ice moves. A bergschrund is a specific type of crevasse that forms where moving glacier ice separates from the stationary ice or snow above, often found near the head of a glacier. Understanding these features is crucial for glacier navigation and studying ice dynamics within alpine and polar environments.
How Crevasses Form on Glaciers
Crevasses form on glaciers due to the differential stress and strain caused by the glacier's movement over uneven terrain, resulting in tensile fractures in the ice. These deep cracks often develop where the glacier flows faster, such as around bends or steep slopes, and can extend tens of meters deep. In contrast, a bergschrund specifically forms at the upper margin of a glacier where the moving ice separates from the stagnant ice or firn above, creating a large crevasse that marks the boundary between the flowing glacier and the immobile snowfield.
The Formation Process of a Bergschrund
A bergschrund forms where moving glacier ice separates from the stagnant ice attached to the mountain slope, creating a large crevasse that marks the transition between the moving and stationary ice. This crevasse develops as the glacier contracts during seasons of intense melting or movement, often found near the head of a glacier or snowfield. Unlike typical crevasses that form due to stress within moving ice, bergschrunds are distinguished by this separation at the glacier margin, playing a crucial role in glacier dynamics and mountaineering hazards.
Distinct Features: Crevasse vs. Bergschrund
Crevasses are deep, irregular cracks that form across glaciers due to differential ice movement, often varying in width and depth, while bergschrunds specifically form at the head of a glacier where moving ice separates from stationary ice or rock. Unlike general crevasses, bergschrunds typically appear as large, persistent openings that mark the transition between the glacier and the mountain slope or snowfield. The distinct formation and location of bergschrunds make them critical identifiers in glaciology and mountaineering compared to the more randomly distributed crevasses across the glacier surface.
Locations Where Crevasses Typically Occur
Crevasses typically form in glacier zones experiencing differential stress, primarily within the brittle upper ice layer where the glacier flows over uneven terrain or steep slopes. They are commonly found in accumulation areas above the firn line, glacier tongues, and near glacier margins due to tensile stress from ice movement. In contrast, bergschrunds are specific types of crevasses that appear at the upper limit of a glacier, separating moving ice from the stationary ice or firn on the mountain slope.
Bergschrund: Where to Find Them on Mountains
Bergschrunds are large, often deep crevasses found near the head of a glacier where moving ice separates from the stationary ice or rock above, typically located high on mountain slopes or in cirques. These features form between the moving glacier and the stagnant ice attached to the mountain, commonly appearing on steep, shaded faces where snow and ice accumulate. Bergschrunds pose significant hazards to climbers due to their size and positioning near crevasse fields, contrasting with crevasses that can occur anywhere on a glacier's surface.
Risks and Dangers: Navigating Crevasses and Bergschrunds
Crevasses and bergschrunds present significant risks due to their hidden depths and unstable ice edges, often leading to fatal falls and entrapment. Navigating these hazards requires expert knowledge in glacier travel techniques, use of ropes, crampons, and ice axes to ensure safety. Proper route planning and constant vigilance for changes in ice conditions are critical to minimizing the dangers associated with these glacial fissures.
Safety Tips for Glacier Travel
Navigating glaciers requires understanding key features like crevasses and bergschrunds, both deep ice fissures posing significant fall risks. Use rope teams, wear crampons, and carry ice axes to arrest falls when crossing or traveling near these hazards. Constantly assess snow bridges over crevasses and bergschrunds for stability and avoid traveling alone to enhance rescue readiness in case of emergencies.
Mountaineering Techniques for Crossings
Crevasses are deep open fractures in glaciers requiring mountaineers to use rope team travel, proper anchor placements, and specialized equipment like ice screws and ladders for safe crossing. Bergschrunds form at the head of a glacier where the moving glacier ice separates from the stationary ice, often creating a large crevasse that demands advanced techniques such as step cutting with an ice axe and precise rope management. Effective crossings depend on assessing snow bridges' stability, practicing self-arrest skills, and employing crevasse rescue procedures to mitigate fall hazards during glacier navigation.
Crevasse and Bergschrund in Climbing History
Crevasses and bergschrunds have played pivotal roles in the history of alpine climbing, often representing significant natural obstacles on glaciers and steep snowfields. Crevasses, deep open cracks in glacier ice, have challenged climbers by requiring specialized techniques and equipment, such as rope teams and ladders, to safely traverse these dangerous gaps. Bergschrunds, a type of crevasse that forms where moving glacier ice separates from the stagnant ice or rock above, frequently mark the critical transition between glacier travel and rock climbing, influencing route choices and ascent strategies in mountaineering history.
Crevasse Infographic
