ijsvallen

Ijsvallen is a term used in glaciology to describe a section of a glacier where ice cascades down a steep slope, creating an irregular surface of broken ice, seracs, and crevasses. The word translates to "icefalls" in English.

They form where a glacier flows over abrupt changes in bed topography, such as cliffs or steep drops, causing differential flow and fracturing. The flow creates crevasses, blocks, and seracs that can collapse and tumble, producing a chaotic ice surface.

Ijsvallen are dynamic features that can advance or retreat with seasonal temperature changes and glacier movement. They pose hazards to mountaineers and researchers due to falling ice, ice avalanches, and hidden crevasses.

Geographically, icefalls occur on many large valley glaciers worldwide, particularly in high mountainous regions. They are common in ranges such as the Alps, the Himalayas, the Andes, and the Karakoram, where steep bedrock and strong gradients prevail.

Etymology: the term derives from Dutch ijs (ice) and val (fall). See also icefall (glaciology), crevasse, serac, and glacier.