Glacier Peak
Dakobed Takobia
East slope of Glacier Peak with Cool (left), Chocolate (descending from summit), North Guardian and Dusty Glaciers (right)
Highest point
Elevation	10,525+ ft (3,207+ m) NAVD 88[1]
Prominence	7,498 ft (2,285 m)[1]
Listing	North America prominent peaks 55th
Coordinates	48°06′43″N121°06′51″W / 48.11194°N 121.11417°W /48.11194; -121.11417[1][2]
Geography
Glacier Peak Washington
Location	Snohomish County,Washington, U.S.
Parent range	Cascade Range
Topo map	USGS Glacier Peak East
Geology
Formed by	Subduction zonevolcanism
Rock age	Pleistocene
Mountain type	Stratovolcano[3]
Volcanic arc	Cascade Volcanic Arc[3]
Last eruption	1700[3]
Climbing
First ascent	1898 by Thomas Gerdine and party[4]
Easiest route	Rock/ice climb on Sitkum Glacier

Glacier Peak orDakobed (known in the Sauk-Suiattle dialect of theLushootseed language as "Tda-ko-buh-ba" or "Takobia"^[5]) is the most isolated of the five majorstratovolcanoes (composite volcanoes) of theCascade Volcanic Arc in theU.S state ofWashington. Located in theGlacier Peak Wilderness inMount Baker–Snoqualmie National Forest, the volcano is visible from the west inSeattle, and from the north in the higher areas of eastern suburbs of Vancouver such asCoquitlam,New Westminster andPort Coquitlam. The volcano is the fourth tallest peak in Washington state, and not as much is known about it compared to other volcanoes in the area. LocalNative 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 inSnohomish 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 famousMount 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 thePleistocene epoch, about one million years ago, and since the most recentice 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.

Remnants of past (prehistoric)lava domes are main components of the summit of the volcano, in addition to its false summit, Disappointment Peak. Pastpyroclastic 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.^[6] On its western flank, the volcano also has alahar, 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 inoxyhornblendedacite; and continued for 30 km (19 mi) into theSauk River.^[7]

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.^[7]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.^[7]

On the mountain, about 5,900 ft (1,800 m) up, are three additionalcinder cones —one at the head of White Chuck River, one atDishpan Gap, and one near Indian Pass.^[8] The volcano has also created thermal features such ashot springs. There were three hot springs on the mountain: Gamma, Kennedy, and Sulphur,^[3] but Kennedy Hot Springs was destroyed and buried in a slide.^[9]

The volcano is located inWashington, and is one of the five major stratovolcanoes there. Situated in theCascade Volcanic Arc, the volcano was created bysubduction of the oceanicJuan de Fuca Plate under theNorth American Plate.^[10] 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.^[11]

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 tonaturalistGeorge Gibbs saying that the volcano had once "smoked".^[6] In 1898 the volcano was finally documented on a map.^[6]

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 theNorthern Pacific Railroad Company searching for possible railroad routes when he saw it in 1870.^[12]

Despite its elevation of 10,541 feet (3,213 m), Glacier Peak is a small stratovolcano. Its relatively high summit is a consequence of its location atop a high ridge, but its volcanic portion extends only 1,600–3,200 feet (500–1,000 m) above the underlying ridge.^[13] Another Cascade Arc volcano with similargeomorphology is theMount Meager massif in southwesternBritish Columbia, Canada, which is situated on a 1,300 ft (400 m) ridge of nonvolcanic, crystalline andmetamorphic rock.^[14]

Of the five major volcanoes in Washington, only Glacier Peak andMount St. Helens have had large eruptions in the past 15,000 years. Since both volcanoes generate magma ofdacitic origin, the viscous magma builds up as it cannot flow through the eruptive vent. Gradually, the pressure grows, culminating in an explosion that ejects materials such astephra, which in its simplest form, isash.^[6]

Tephrochronology andradiocarbon dating indicate that Glacier Peak eruptions occurred in 1700AD ± 100 years, 1300 AD ± 300 years, 900 AD ± 50 years, 200 AD ± 50 years, 850 BC, 3150 BC, and in 3550 BC. TheVolcanic Explosivity Index (VEI) for three of these was 2 to 4, small compared to the 5 of the1980 eruption of Mount St. Helens. They were characterized mainly by a central vent eruption, followed by an explosive eruption. These eruptions varied in outcome; some producedlahars, somepyroclastic flows, and otherslava domes.^[3] The volcano has had one eruption with aVEI of 2, one with a VEI of 4, and possibly another with a VEI of 3.^[15]

A little more than 13,000 years ago, a sequence of nine tephra eruptions occurred within a period of less than a few hundred years. Associated with these eruptions were pyroclastic flows. Mixed with snow, ice and water, these formed lahars that raced into three nearby rivers, filling their valleys with deep deposits. Subsequently, the mudflows drained into both the North Fork of theStillaguamish River (at that time an outlet of theSauk River) andSkagit Rivers. InArlington, 60 miles (97 km) downstream, lahars deposited seven feet of sediment. Subsequent erosion of lahar deposits nearDarrington led to the current river system with the Stillaguamish River separated from the Sauk/Skagit Rivers. Lahar debris was deposited along both the Skagit and Stillaguamish Rivers all the way toPuget Sound. A small portion of the erupted tephra was deposited locally. However, most of the tephra reached higher levels of the atmosphere, and was transported by the wind hundreds of miles. Deposits from this congregation were as thick as 1 foot (0.30 m) nearChelan and 0.3 inches (7.6 mm) nearMissoula, Montana.^[6] The table below shows the three largest eruptions from this sequence.^[16]

Since these events, Glacier Peak has produced several lahars. The largest mudflows were 5,900 and 1,800 years ago and were associated with dome-building eruptions. In both cases, the lahars traveled down the Skagit River to Puget Sound.^[6]

The risk of an eruption in any given year is currently estimated as 1 in 1,000.^[17] As of 2018^[update], Glacier Peak is classified as one of the 18 most dangerous volcanoes in the United States.^[18]

When lahars reach populated areas, they can bury structures and people. An example was theArmero tragedy atNevado del Ruiz where 23,000 died from an enormous mudflow. Lahars from Glacier Peak pose a similar threat to the small communities of Darrington, Arlington, andConcrete with a lesser threat to the larger and rapidly growing towns ofMount Vernon andBurlington, as well as other communities along the lower Skagit and Stillaguamish Rivers.^[6] A 2005 study conducted by theUnited States Geological Survey identified nine Cascade volcanoes, including Glacier Peak, as "very-high-threat volcanoes with inadequate monitoring". At the time of the study, only one seismometer was installed on Glacier Peak that had not "worked in two years".^[19] As of 2023^[update], thePNSN still operates only one seismometer on Glacier Peak.^[20]

In 2018, theUSGS applied to add four more stations, but regulations protecting federalwilderness areas prohibit the use of helicopters that are needed to transport materials; advocacy groups opposed an exemption for the project and filed objections.^[21][22] In 2019, Congress passed the National Volcano Early Warning and Monitoring System Act to authorize more monitoring stations, but did not include funding to construct them.^[23] Permits were granted by the U.S. Forest Service in June 2022.^[24]

Eleven significant glaciers cover Glacier Peak. When C.E. Rusk first saw these glaciers in 1906 they were beginning to retreat, but were still very advanced. The average retreat of Glacier Peak glaciers from theLittle Ice Age to the 1958 positions was 5,381 feet (1,640 m).Richard Hubley noted that North Cascade glaciers began to advance in the early 1950s, after 30 years of rapid retreat. The advance was in response to a sharp rise in winter precipitation and a decline in summer temperature beginning in 1944. Ten of the fifteen glaciers around Glacier Peak advanced, including all of the glaciers directly on the mountain's slopes. Advances of Glacier Peak glaciers ranged from 50 to 1,575 feet (15 to 480 m) and culminated in 1978. All eleven Glacier Peak glaciers that advanced during the 1950–79 period emplaced identifiable maximum advance terminal moraines. From 1984 to 2005, the average retreat of eight Glacier Peak glaciers from their recent maximum positions was 1,017 feet (310 m). Milk Lake Glacier, on the north flank of the mountain, melted away altogether in the 1990s.^[26] Due to global warming, glaciated area shrunk by a third by 2025 and is estimated to be almost gone by 2075.^[27]

ThePacific Crest Trail passes near Glacier Peak. TheSuiattle River crossing is a well-known feature on the Pacific Crest Trail (PCT) as it passes through the area. The Suiattle PCT crossing used to have a bridge crossing until it was flooded out by storms in late 2003.^[28]

The first recorded person to climb the mountain was Thomas Gerdine, along with a group ofUnited States Geological Survey scientists, Sam Strom, A. H. Dubor, and Darcy Bard, in 1897.^[4] The climb isAlpine Grade I or II.^[29]

The easiest ski route is about 5 miles (8.0 km) of walking along the White Chuck River Trail (Forest Service Trail No. 643) and up the Sitkum Glacier. The trail is reached via Forest Service Road No. 23. The Sitkum Glacier ski route is rated blue toblack diamond for both the ascent and the descent.^[30]

The Seattle-based composer,Alan Hovhaness, dedicated his Symphony no.66 as "Hymn to Glacier Peak": seeSymphony no.66 (Hovhaness).

The non-fiction bookEncounters with the Archdruid by John McPhee, which portrays the environmental advocacy ofDavid Brower, devotes the first of its three main sections to a conflict over mineral prospecting around Glacier Peak.

• List of mountain peaks of North America
  • List of mountain peaks of the United States
    • List of mountain peaks of Washington (state)
      • List of highest points in Washington by county
• List of Ultras of the United States
• List of volcanoes in the United States

• Glacier Peak on Ski Mountaineer.com
• "Glacier Peak".Peakware.com. Archived fromthe original on March 4, 2016.
• "Glacier Peak".SummitPost.org.
• University of Washington Libraries Digital Collections – The Mountaineers Collection Photographic albums and text documenting the Mountaineers official annual outings undertaken by club members from 1907 to 1951, primarily on the Olympic Peninsula, in Mount Rainier National Park and on Glacier Peak.

• Cascade Range
• Cascade Volcanoes
• Holocene stratovolcanoes
• Landforms of Snohomish County, Washington
• Mount Baker-Snoqualmie National Forest
• Mountains of Snohomish County, Washington
• Three-thousanders of the United States
• North Cascades of Washington (state)
• Pleistocene stratovolcanoes
• Religious places of the Indigenous peoples of North America
• Stratovolcanoes of the United States
• Stratovolcanoes of Washington
• Subduction volcanoes
• VEI-5 volcanoes
• Volcanoes of Washington (state)
• Sacred mountains of the United States
• Active volcanoes
• VEI-4 volcanoes
• VEI-2 volcanoes

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