 The glacier, which was still on the move, then blocked the gorge causing it to fill up with meltwater.A second mudflow surge occurred on July 6 when a 9 km stretch of the valley floor was buried underneath a mass of ice and rocks.Its thickness at times approached 50 m, the scouring of the valley slopes reaching a height of 100 m. The estimated volume of ice that was ejected into the valley, obstructing the gorge, was in excess of 100 million m3.