rockfall
From Longman Dictionary of Contemporary Englishrockfallrock‧fall /ˈrɒkfɔːl $ ˈrɑːkfɒːl/ noun [countable] a pile of rocks that are falling or have fallenExamples from the Corpusrockfall• Jagged boulders from rockfalls triggered by ice and rushing water made progress difficult.• The rockfall lasted at least a minute.• The scale of this rockfall certainly suggests that there will continue to be collapses on this popular buttress.