Other mass movements include icefalls, landslides, and rockfalls. Small valley glaciers form icefalls where they meet the trunk glacier. Much larger icefalls may be found in the outlet glaciers of continental ice sheets. Icefalls at the head provide the main ice flow into the Towle Glacier. The valley receives little sun in winter and icefalls form on the valley sides. Icefalls are climbed because of their beauty and the challenge they pose.