“After the passage of the main glacier of Tenaya in the direction of the arrows there seems to have been some lingering ice which flowed downwards eroding shallow groove channels”

Half Dome

The glacier that swept down Tenaya Canyon from the High Sierra likely ran along below the full dome and tore off rock that supported the face. The northwest side of the dome collapsed over time, and glaciers carried and pushed the rockfall toward the west end of Yosemite Valley.