A mass of falling and tumbling rock, debris, and soil traveling at a high velocity owing to the presence of ice or water is a _____ rockfall. mudflow. debris avalanche. landslide.
Due to the fact that you said ice or water I'm thinking a mudflow but it could be a landslide considering the rock and debris but I'm almost certain its a mudflow because mudflows happen at high velocities, or quickly than all the other options you have there.
