Glacier Peak or Dakobed (known in the Sauk-Suiattle dialect of the Lushootseed language as "Tda-ko-buh-ba" or "Takobia") is a stratovolcano in the U.S state of Washington. Located in the Glacier Peak Wilderness in Mount Baker–Snoqualmie National Forest, the volcano is visible from the west in Seattle, and from the north in the higher areas of eastern suburbs of Vancouver such as Coquitlam, New Westminster and Port Coquitlam. The volcano is the fourth tallest peak in Washington state and the most isolated volcano of the Cascade Volcanic Arc. Compared to other volcanoes in the areas, relatively less is known about Glacier Peak. Local Native Americans have recognized Glacier Peak and other Washington volcanoes in their histories and stories. When American explorers reached the region, they learned basic information about surrounding landforms, but did not initially understand that Glacier Peak was a volcano. Positioned in Snohomish County, the volcano is only 70 miles (110 km) northeast of downtown Seattle. From locations in northern Seattle and northward, Glacier Peak is closer than the more famous Mount Rainier (Tahoma), but as Glacier Peak is set farther into the Cascades and almost 4,000 feet (1,200 m) shorter, it is much less noticeable than Mount Rainier. Glacier Peak is the second most active of Washington's volcanoes, with eruptions as recently as 1700 AD ± 100 years. The volcano formed during the Pleistocene epoch, about one million years ago, and since the most recent ice age, it has produced some of the largest and most explosive eruptions in the state. When continental ice sheets retreated from the region, Glacier Peak began to erupt regularly, erupting explosively five times in the past 3,000 years. It has erupted repeatedly during at least six periods; two of these eruptions have been among the largest in Washington.
Geology Remnants of past (prehistoric) lava domes are main components of the summit of the volcano, in addition to its false summit, Disappointment Peak. Past pyroclastic flow deposits are easily visible in river valleys near the volcano, likely caused by lava dome collapse, along with ridges found east of the summit consisting of ash cloud remains. On its western flank, the volcano also has a lahar, or mudflow deposit, which runs for about 22 miles (35 km) into the White Chuck River Valley around 14,000 years ago. Ten other pyroclastic flow deposits are visible, all identified as relatively 10,000 years old. There is also a considerably newer mudflow, about 5,500 years old, which covers an area of 9.3 mi (15 km) between the same river valley, along with two small incidents both under 3,000 years old. Another lahar, of unidentified age, was rich in oxyhornblende dacite; and continued for 30 km (19 mi) into the Sauk River. There are also ash cloud deposits on the opposite eastern flank of the volcano. Studies of the mountain have to date been unable to find any correspondence with pyroclastic flows, but several past mudflows have been identified. In the Dusty Creek valley, which runs east from the mountain, there is a lahar at least 98 ft (30 m) thick, containing pyroclastic flow deposits and other mudflows. However, this large mudflow is part of a 980-foot-thick (300 m) concentration of past incidents at the volcano that spans the Dusty Creek and Chocolate Creek valleys. The area contains at least 2.4 cubic miles (10 km3) of lithic debris. Tephra deposits are for the most part constrained to the left flank of the volcano, and at least nine past incidents have been identified. These form several layers of tephra constructing the mountain. Smaller eruptions involving tephra occurred between 6,900 and 5,500 years ago, again between 3,450 and 200 years ago, and as recently as 316 to 90 years ago. On the mountain, about 5,900 ft (1,800 m) up, are three additional cinder cones — one at the head of White Chuck River, one at Dishpan Gap, and one near Indian Pass. The volcano has also created thermal features such as hot springs. There were three hot springs on the mountain: Gamma, Kennedy, and Sulphur, but Kennedy Hot Springs was destroyed and buried in a slide.
Tectonic setting
The volcano is located in Washington, and is one of the five major stratovolcanoes there. Situated in the Cascade Volcanic Arc, the volcano was created by subduction of the oceanic Juan de Fuca Plate under the North American Plate. Convergence between the two continues at a rate of 1.6 inches (4 cm) per year. This range has been volcanically active for about 36 million years, and the rocks that make up its volcanoes are between 55 and 42 million years old. Eruptions within the range are irregular and do not occur all at once. In an attempt to organize the volcanoes by age, scientists typically divide them into the High Cascades, younger volcanoes, and the Western Cascades, consisting of the older volcanoes. However, the vents in Washington are all of different ages so none of its volcanoes are included in either of the sections.
History Around the area, there were many Native Americans, and along with other Washington volcanoes, the mountain was recognized by them as a spirit. When European-American explorers reached the area, they learned about the mountain, though only partially, through local legends. Although the local people described Glacier Peak as a vital part of their storytelling and beliefs, when other volcanoes in the area were mapped, Glacier Peak was left out. In 1850 natives mentioned the volcano to naturalist George Gibbs saying that the volcano had once "smoked". In 1898 the volcano was finally documented on a map. Native Americans also used the area around the Cascades for their agriculture, leading them to often congregate in the region. As a result, gold miners eventually reached the area in the 1870s–1890s, searching for resources and rich land. The first white man recorded to observe the mountain—Daniel Lindsley—was an employee of the Northern Pacific Railroad Company searching for possible railroad routes when he saw it in 1870.
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