Osceola Mudflow

It traveled down the west and main forks of the White River, passed the location of present-day Enumclaw then reached Puget Sound in several areas, including near the present day sites of Tacoma and Auburn.

Many communities in King and Pierce counties, notably Kent, Enumclaw, Orting, Buckley, Sumner, Puyallup and Auburn, are wholly or partly located on top of Osceola Mudflow deposits which reach a depth of up to 100 m (330 ft).

The depression then filled over time with ice (Emmons Glacier) and lava flows from a central vent.

Russell Cliff, Liberty Cap, Point Success, and Disappointment Cleaver, surround this feature.

[1] Using the dipping lava beds upward, it has been estimated the height of Mount Rainier was about 4,900 metres (16,100 ft).

Down valley, near Sumner on the Auburn and Puyallup deltas, of the prehistoric Puget Sound, the mudflow is 20 to 30 metres (66 to 98 ft) deep.

[1] This article incorporates public domain material from websites or documents of the United States Geological Survey.

Detailed map of Mount Rainier's summit and northeast slope showing upper perimeter of Osceola collapse amphitheater (hachured line)
Mount Rainier with its main summit, Columbia Crest (14410 feet) at the center. Emmons Glacier covers most of the visible flank of the mountain with Disappointment Cleaver visible below Gibraltar Rock, right of the sharp pointed Little Tahoma (11138 feet). Liberty Cap (14112 feet) is visible on the right center skyline behind Russell Cliff.