Glaciers and Their Effects at Mount Baker
After Mount Rainier, Mount Baker is the most heavily glaciated of the Cascade volcanoes. The glaciers, and the volcanic field itself, are drained by approximately 30 white- water tributaries of the Nooksack River and the Baker River branch of the Skagit River. Glacial ice has influenced the distribution of eruptive products, contributed to the size of lahars, and amplified erosion throughout the lifetime of the volcanic field. Unlike many other glaciers in the continental US, which are experiencing rapid retreat throughout the past several decades, Mount Baker’s glaciers remain relatively healthy due to large yearly snowfalls.
Mount Baker is the only Cascade volcano in the US to have been subject to both alpine and continental glaciation. Alpine glaciers form on discrete peaks at high elevations, as a result of cool air and snow accumulation, and flow down valleys. During cooler climates, alpine glaciers extended past the base of the volcano, but today they only exist at upper elevations. Continental glaciation covers large landmasses and stretch from colder northerly latitudes to the south and terminate where warmer temperatures prevent their existence at lower latitudes. As glaciers advance and retreat, they erode the landscape. At Mount Baker, the resulting glacial erosion removed much of the evidence of the many eruptive centers that were present before and during the continental glaciation. All that remain are isolated scraps of volcanic deposits on the surface and dikes indicating where magma travelled beneath the surface. Glacial erosion is directly responsible for the rarity of pyroclastic and debris-flow deposits in the Mount Baker area.
The last great continental ice mass in the Pacific Northwest, the Cordilleran Ice Sheet, approached Mount Baker from both the west and the east and retreated from the area about 15,000 years ago. The moraines from the Cordilleran Ice Sheet dammed a lake in the Baker River valley from about 15,000 years ago to the recent times.