DESCRIPTION:

 Mount Garibaldi Volcano, British Columbia, Canada

Geographic Setting, and Geologic and Eruptive History—

 Garibaldi

 Location: British Columbia, Canada Latitude: 49.85 N Longitude: 123.00 W Height: 2,678 meters (8,787 feet)

 Type: Stratovolcano

 Lastest Eruptions: About 10,000 (?) years ago.  Nature or products of eruptions: Lava flows; fragmental pyroclastic deposits.

 Present thermal activity: None, may be extinct. Remarks: Volcano’s core is solid dacite rocks. Most of cone comprises fragmental material that was     deposited on surrounding ice of continental glacier. 2 Mount Garibaldi is a composite cone and domes built on a glacier. Early activity was between       0.26  and 0.22 million years ago.

 Atwell Peak erupted approximately 13,000 years ago. Opal Cone was

 post-Wisconsin glacial stage. No historic activity.3

 Compiled From: 1 Smithsonian Institution - Global Volcanism Program, 2

 Foxworthy and Hill, 1982, Volcanic Eruptions of 1980 at Mount St. Helens,

 The First 100 Days: USGS Professional Paper 1249, and 3 Wood and Kienle,

 1990, Volcanoes of North America: United States and Canada: Cambridge

 University Press

 Mount Garibaldi Volcano

 From: Wood and Kienle, 1990, Volcanoes of North America: United States and

 Canada: Cambridge University Press, 354p., p.144-145, Contribution by William H. Mathews

 Mount Garibaldi is one of the larger volcanoes (6.5 cubic kilometers) in a chain of small Quaternary volcanic piles—the Garibaldi Belt—which trend

  N25degrees W within the southern Coast Mountains of British Columbia. Mount Garibaldi is noteworthy both for the excellent exposures of its

  internal structure and for its striking topographic anomalies, which can be attributed to the growth of the volcano onto a major glacial stream, part

  of the Cordilleran Ice Sheet, and the subsequent collapse of the flanks of the volcano with the melting of the ice.                          

 The western slopes of the mountain reveal basement rocks, sheared and altered quartz diorite, sculptured by streams and glaciers into a rugged

  topography with relief up to 1,800 meters. ...

 Eruptions from the site of the south summit (Atwell Peak) then created a conical pile of tuff-breccia at least 700 meters thick at its apex. ...

 Unweathered glacial erratics are found resting on a remnant of the original top surface of the tuff-breccia deposit up to, but not above, the 1,660

 meter level, almost 300 meters lower than expected had volcanism here preceded the climax of Wisconsin glaciation. ... Only where basement rocks

 extend above the 1,400 meter level do the tuff-breccias lie undisturbed; below this level they are considered to have been deposited on glacier ice.

 With continuing retreat

 of the ice the support was withdrawn from those parts of the tuff-breccia cone which had been built onto the ice, causing collapse in a series of l

 andslides which ultimately exposed the inner parts of the cone. Later volcanism from the western summit formed lava flows which mantled the

landslide headwall on the west side of the mountain. About the same    time a satellite vent, Opal Cone, 3.5 kilometers southeast of the summit,

 gave rise to a voluminous (4.5 cubic kilometer) hornblende-biotite dacite flow  wich moved 20 kilometers down Ring Creek without encountering any

 residual glacial ice. These eruptions have been assigned to early Holocene time.  There has been no subsequent eruption at Mount Garibaldi. ...

 Mount Garibaldi is located 80 kilometers north of Vancouver, British Columbia, in the Garibaldi Provincial Park. Good view of the volcano are

 approximately 25 and 55 kilometers north of Vancouver along Highway 99. Hiking is required to reach Garibaldi itself.