Kohala is a shield volcano cut by multiple deep gorges, which are the product of thousands of years of erosion. Unlike the typical symmetry of other Hawaiian volcanoes, Kohala is shaped like a foot. Toward the end of its shield-building stage 250,000 to 300,000 years ago, a landslide destroyed the northeast flank of the volcano, reducing its height by over and traveling across the sea floor. This huge landslide may be partially responsible for the volcano's foot-like shape. Marine fossils have been found on the flank of the volcano, far too high to have been deposited by standard ocean waves. Analysis indicated that the fossils had been deposited by a massive tsunami approximately 120,000 years ago.