Which process drives cirque formation when glacial ice accumulation fluctuates?

💡 Explanation

When ice accumulation changes, the freeze-thaw action increases because regelation cycles accelerate frost wedging which fractures bedrock. Nivation, through chemical and physical weathering enhanced by snow cover, further degrades materials within the cirque basin. Therefore frost wedging and nivation erode the headwall, rather than volcanism, rebound, or weathering which contribute negligibly at cirque locations.

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