Which mechanism primarily causes cirque expansion in periglacial environments?

💡 Explanation

When water freezes within cracks along the bergschrund, frost wedging expands the cirque headwall because ice volume increases, generating pressure exceeding the rock strength, causing fracturing and removal. Therefore frost wedging results, rather than ablation, sliding, or chemical weathering, which are less effective at headwall erosion.

• Which mechanism causes the episodic tremor and slip (ETS) phenomenon along subduction zone faults?
• Which mechanism inhibits stratovolcano formation at convergent plate boundaries with rapid subduction?
• Which mechanism initiates upwelling along transform fault zones in oceanic ridges?
• Which mechanism explains coral bleaching during a strong El Niño event in the Pacific Ocean?
• Which mechanism initiates oxbow lake formation in a meandering river system given constant flow?
• Which geologic outcome occurs when a river's slope abruptly decreases at the base of a mountain range?