Geological Survey Bulletin 1221-A Rockfalls and Avalanches from Little Tahoma Peak on Mount Rainier, Washington

Little Tahoma Peak forms the highest part (11,117 ft) of a broad wedge pointing toward the top of Mount Rainier, about 2 miles to the west (fig. 1). The wedge is made up of volcanic breccia and rubble interlayered with lava flows that slope down the flank of the volcano in an easterly direction. Both the north and south sides of Little Tahoma Peak rise steeply about 2,000 feet above the flanking glaciers. The cliffs are largely the result of continuing erosion by a broad sheet of ice that flows down the east flank of Mount Rainier. This ice splits at Little Tahoma Peak into the southeast-flowing Ingraham Glacier and the northeast-flowing Emmons Glacier. Emmons Glacier now terminates about 2.5 miles downvalley from Little Tahoma Peak.

Prior to December 1963, the White River just beyond Emmons Glacier occupied a valley floor about 500 feet wide, which was flanked on the northwest by lateral moraines and stagnant ice and on the southeast by Goat Island Mountain. Farther downvalley the valley floor is constricted by a large terminal moraine which was formed at the front of Emmons Glacier between about 1700 and the early 1900's (Crandell and Miller, 1964) (fig. 2). The White River still flows through this constriction but is now about 300 feet south of its pre-avalanche course.