Typically, during the day the ice melts and water collects in fissures. At night the water freezes and expands in these cracks and causes pieces to break off.
इससे शैल के आकार में एक आकस्मिक परिवर्तन आता है, जो उसके गुरुत्व - केन्द्र को बदल देता है ।