Mount Meager massif
The Mount Meager massif is a group of volcanic peaks in the Pacific Ranges of the Coast Mountains in southwestern British Columbia, Canada. Part of the Cascade Volcanic Arc of western North America, it is located 150 km north of Vancouver at the northern end of the Pemberton Valley and reaches a maximum elevation of 2,680 m; the massif is capped by several eroded volcanic edifices, including lava domes, volcanic plugs and overlapping piles of lava flows. The Garibaldi Volcanic Belt has a long history of eruptions and poses a threat to the surrounding region. Any volcanic hazard ranging from landslides to eruptions could pose a significant risk to humans and wildlife. Although the massif has not erupted for more than 2,000 years, it could produce a major eruption. Teams such as the Interagency Volcanic Event Notification Plan are prepared to notify people threatened by volcanic eruptions in Canada; the Mount Meager massif produced the largest volcanic eruption in Canada in the last 10,000 years.
About 2,400 years ago, an explosive eruption formed a volcanic crater on its northeastern flank and sent avalanches of hot ash, rock fragments and volcanic gases down the northern flank of the volcano. Evidence for more recent volcanic activity has been documented at the volcano, such as hot springs and earthquakes; the Mount Meager massif has been the source of several large landslides in the past, including a massive debris flow in 2010 that swept down Meager Creek and the Lillooet River. The Mount Meager massif lies in the Coast Mountains, which extend from Vancouver to the Alaskan Panhandle for 1,600 km, it is about 300 cut by fjords, narrow inlets with steep cliffs created by glacial erosion. The Coast Mountains have a profound effect on British Columbia's climate. Lying just east of the Pacific Ocean, they shear off moisture-laden air coming off the ocean, causing heavy rainfall on their western slopes; this precipitation is among the most extreme in North America, feeding lush forests on the mountain range's western slopes.
Valleys surrounding the massif contain old-growth forests. The area features wetland habitats, plants of the cottonwood-willow-thimbleberry association and glaucous willowherbs. Wildlife such as wolves, moose, black-tailed deer, mountain goats and waterfowl inhabit the area as well as grizzly and black bears; the Mount Meager massif is part of the Garibaldi Volcanic Belt, the northernmost segment of the Cascade Volcanic Arc. This volcanic belt includes cinder cones, calderas and subglacial volcanoes that have been active in the last 10,000 years; the latest explosive eruption in the Garibaldi Volcanic Belt occurred at a crater on the northeastern slope of the massif about 2,400 years ago, which forms a defined depression. The GVB extends north from the Watts Point volcano to at least as far as the Meager massif; because little is known about the volcanoes north of the massif, such as the Silverthrone and Franklin Glacier volcanic complexes, experts disagree about their nature. Some scientists regard the Silverthrone Caldera as the northernmost volcano of the Garibaldi Volcanic Belt, while others contend that the geology of the massif more matches that of the GVB.
It is unclear whether the Milbanke Sound Cones are part of the Garibaldi Belt or formed by different tectonic processes. However, there is evidence the Silverthrone and Franklin Glacier complexes are related to activity at the Cascadia subduction zone. Geologically these two volcanoes contain the same rock types as those found elsewhere in the Cascade Arc, including rhyolites, dacites and basaltic andesites; such rock types are produced by subduction zone volcanism indicating volcanism at Silverthrone and Franklin Glacier is related to subduction. If these two volcanoes are true Cascade Arc volcanoes, the Mount Meager massif is not the northernmost volcano of the Garibaldi Belt or the Cascade Arc. Volcanism in the Cascade Volcanic Arc is caused by subduction of the Juan de Fuca Plate under the North American Plate at the Cascadia subduction zone; this is a 1,094 km long fault zone lying 80 km off the Pacific Northwest from Northern California to southwestern British Columbia. The plates move at a relative rate of more than 10 mm per year at an oblique angle to the subduction zone.
Because of the huge fault area, the Cascadia subduction zone can produce large earthquakes of magnitude 7.0 or greater. The interface between the Juan de Fuca and North American plates remains locked for periods of 500 years. During these periods, stress builds up on the interface between the plates and causes tectonic uplift of the North American margin; when the plate slips, it releases 500 years of stored energy in a massive earthquake. Unlike most subduction zones worldwide, there is no deep oceanic trench present along the continental margin in Cascadia; the mouth of the Columbia River empties directly into the subduction zone and deposits silt at the bottom of the Pacific Ocean, burying this large depression, or area of sunken land. Massive floods from prehistoric Glacial Lake Missoula during the Late Pleistocene deposited large amounts of sediment into the trench. However, as with other subduction zones the outer margin is being compressed like a giant spring; when the stored energy is released by slippage across the fault at irregular intervals, the Cascadia subduction zone can create enormous earthquakes such as the magnitude 9.0 Cascadia earthquake on January 26, 1700.
However earthquakes along the Cascadia
British Columbia Coast
The British Columbia Coast or BC Coast is Canada's western continental coastline on the North Pacific Ocean. The usage is synonymous with the term West Coast of Canada. In a sense excluding the urban Lower Mainland area adjacent to the Canada–United States border, considered "The Coast," the British Columbia Coast refers to one of British Columbia's three main regions, the others being the Lower Mainland and The Interior; the aerial distance from Victoria on the Strait of Juan de Fuca to Stewart, British Columbia on the Alaska border at the head of the Portland Canal is 965 kilometres in length. However, because of its many deep inlets and complicated island shorelines—and 40,000 islands of varying sizes, including Vancouver Island and Haida Gwaii —the total length of the British Columbia Coast is over 25,725 kilometres, making up about 10% of the Canadian coastline at 243,042 kilometres; the coastline's geography, shared with Southeast Alaska and adjoining parts of northwest Washington, is most comparable to that of Norway and its indented coastline of fjords, a landscape found in southern Chile.
The dominant landforms of the BC Coast are the Insular Mountains, comprising most of Vancouver Island and Haida Gwaii, the Coast Mountains, which extend beyond into Alaska and the Yukon. The British Columbia Coast is part of the Pacific temperate rain forests ecoregion as defined by the World Wide Fund for Nature. In the system used by Environment Canada, established by the Commission for Environmental Cooperation, the area is defined as the Pacific Maritime Ecozone. In the geoclimatic zones system used by the British Columbia Ministry of Forests the bulk of the region comprises the Coastal Western Hemlock biogeoclimatic zone, although small areas flanking the Strait of Georgia at the coast's southern extremity are classed in the Coastal Douglas-fir zone; the great fjords of the British Columbia Coast rival those of Norway in length and depth but have higher mountain scenery with a more alpine flavour. Many of the islands offshore are much larger than those along the Norwegian coast, many large enough to have major fjords of their own, as well as their own mountain ranges.
This is of course more true of the large islands farther offshore, Vancouver Island and Graham and Moresby Islands in Haida Gwaii, which together form the Insular Mountains, distinct from the Coast Mountains of the mainland. Here are the most important fjords, inlets and sounds, including those important for reasons other than their size, listed south to north: The many fjord-like waterways between the coast and the islands, within the archipelago, cannot be listed here, there are many more others that are not so much fjord-like as flooded valleys between what had been mountain peaks many thousands of years ago, when the shoreline was lower; the waterway route through these islands between Vancouver and Prince Rupert, between Seattle and Alaska, is known as the Inside Passage. It has played a role in U. S.-Canada relations more than once, from the Klondike Gold Rush to the Salmon War of the 1990s. Major and important waterways are: Vancouver Island Haida Gwaii Graham Island Moresby Island Louise Island Lyell Island Kunghit Island Porcher Island Pitt Island McCauley Island Banks Island Gil Island Gribbell Island Hawkesbury Island Princess Royal Island Aristazabal Island Price Island Swindle Island Campbell Island Denny Island Hunter Island King Island Calvert Island Caamano Island Malcolm Island Broughton Archipelago Broughton Island Gilford Island Knight Inlet West/East Cracroft Islands Knight Inlet Hardwicke Island Johnstone Strait Discovery Islands East Thurlow Island West Thurlow Island Sonora Island Maurelle Island Read Island Raza Island Quadra Island Cortes Island East Redonda Island West Redonda Island Hernando Island Stuart Island Rendezvous Islands Nelson Island Northern Gulf Islands: Savary Island Texada Island Lasqueti Island Hornby Island Denman Island The above list ends at the northern Strait of Georgia, the last several forming a group known as the northern Gulf Islands.
The southern Gulf Islands are as follows: Gabriola Island Valdes Island Thetis Island Kuiper Island Saltspring Island Prevost Island Galiano Island Mayne Island North Pender Island South Pender Island Saturna Island Sidney Island James IslandThe Gulf Islands continue southeast across the Haro Straits as the San Juan Islands. The islands of Howe Sound are classed among the southern Gulf Islands, but they adjoin the mainland rather than Vancouver Island and are considered separately, they are: Bowen Island Gambier Island Anvil Island Keats island Bowyer IslandThe islands of the Fraser River estuary are: Barnston Island Lulu Island Sea Island Westham Island Iona Island Deas Island Annacis Island Research from the 1990s has indicated that the Ice Age-era coastline of the British Columbia Coast was lower by about 100 metres. The effect of the waterlevel on the coastline was such that the Queen Charlotte Strait, between Haida Gwaii and the northern end of Vancouver Island, was a coastal plain, as were all the straits inland from it, except for those that were mountain valleys.
Underwater archaeology has shown the presence of permanent human habitations and other activity at the 100-metre contour, the Ice Age existence of such a coastal plain has put a new light on Ice Age populations in North America as well as on the strong likeli
HMS Plumper (1848)
HMS Plumper was an 8-gun wooden screw sloop of the Royal Navy, the fifth and last ship to bear the name. Launched in 1848, she served three commissions, firstly on the West Indies and North American Station on the West Africa Station and in the Pacific Station, it was during her last commission as a survey ship. She paid off for the last time in 1861 and was sold for breaking up in 1865; the Admiralty ordered the ship on 25 April 1847 from Woolwich Dockyard as the steam schooner Pincher. She was re-ordered from Portsmouth Dockyard as the screw sloop Plumper on 12 August 1847 to a design by John Fincham, laid down in October that year, she was launched on 5 April 1848 at Portsmouth and commissioned under Commander Mathew Nolloth on 17 December. Plumper was the only ship built to the design, she was constructed of wood, was 140 feet 0 inches long and 27 feet 10 inches in the beam, drew 11 feet 4 1⁄2 inches. This hull gave her a displacement of 577 tons, she was powered by a Miller, Ravenhill & Co two-cylinder vertical single-expansion steam engine driving a single screw.
Developing 148 indicated horsepower, this unit was capable of driving her at 7.4 knots. Illustrations show her with a barque rig, although this may have been a alteration, her armament of 8 guns consisted of six 32-pounder and two 32-pounder muzzle-loading smooth-bore guns mounted to fire in a traditional broadside arrangement. After commissioning at Portsmouth, Plumper joined the Channel Fleet under Admiral Sir Charles Napier, in January 1849 was sent to the North America and West Indies Station. Curiously, a report was published in the Illustrated London News on 14 April 1849 of a sighting of a sea serpent off the Portuguese Coast. On 25 June 1850, she was damaged off Digby, Nova Scotia, British North America, she was taken in to Digby for repairs. In June 1851 she deployed to the south-east coast of America and during this period she captured the slavers Flor-do-Mar on 14 June 1851 and Sarah on 9 June 1851, she is recorded as arriving in Portsmouth from Brazil with 6,370 troy ounces of gold trans-shipped from the Emperor on 31 December 1852.
She paid off at Portsmouth on 6 January 1853. Plumper recommissioned at Portsmouth on 1 August 1853 under Commander Wharton for service on the west coast of Africa. At the time, the West Africa Squadron was employed overwhelmingly in anti-slavery patrols, the London Gazette records the capture of a slaving vessel of unknown name by Plumper on 19 October 1855. From 5 April 1855 she was commanded by Commander William Henry Haswell and she paid off at Portsmouth on 9 December 1856. For her third commission, the Plumper was converted to a survey ship, it is probable that her armament was increased at this time to 12 guns, her captain from 1857 until January 1861 was Captain George Henry Richards. She was used to survey the coast of British Columbia, in particular the Fraser River, Burrard Inlet, Howe Sound, Sunshine Coast and Esquimalt; the Plumper, having embarked a company of Royal Marines, was involved in the Pig War crisis between the United States and Britain in 1859. Francis Brockton was the ship's engineer under Captain Richards when, in 1859, Brockton found a vein of coal in the Vancouver area.
After the discovery, which Richards reported to Governor James Douglas, Richards named the area of the find Coal Harbour and named Brockton Point, at the east end of what is now Stanley Park in Vancouver, after Francis Brockton. Commander Anthony Hoskins brought HMS Hecate out to the Pacific Station and swapped commands with Richards, taking command of the Plumper in January 1861, he returned to the United Kingdom, paying the ship off at Portsmouth on 2 July 1861. Plumper was sold to White of Cowes for breaking on 2 June 1865. Several significant features of the coast of British Columbia are named after Plumper, including Plumper Sound in the Southern Gulf Islands region of British Columbia and Plumper Cove at Keats Island. Other features were named after the ship's company, including: Campbell River, British Columbia for Dr Samuel Campbell, the ship's surgeon. Pender Island and Pender Harbour, British Columbia for Daniel Pender. Mayne Island for Lieutenant Richard Charles Mayne. Brockton Point for the ship's engineer, Francis Brockton.
Mudge Island for William Fitzwilliam Mudge, a ship's officer. An image of the ship appears on the coat-of-arms of the town of Sidney on southern Vancouver Island
British Columbia is the westernmost province of Canada, located between the Pacific Ocean and the Rocky Mountains. With an estimated population of 5.016 million as of 2018, it is Canada's third-most populous province. The first British settlement in the area was Fort Victoria, established in 1843, which gave rise to the City of Victoria, at first the capital of the separate Colony of Vancouver Island. Subsequently, on the mainland, the Colony of British Columbia was founded by Richard Clement Moody and the Royal Engineers, Columbia Detachment, in response to the Fraser Canyon Gold Rush. Moody was Chief Commissioner of Lands and Works for the Colony and the first Lieutenant Governor of British Columbia: he was hand-picked by the Colonial Office in London to transform British Columbia into the British Empire's "bulwark in the farthest west", "to found a second England on the shores of the Pacific". Moody selected the site for and founded the original capital of British Columbia, New Westminster, established the Cariboo Road and Stanley Park, designed the first version of the Coat of arms of British Columbia.
Port Moody is named after him. In 1866, Vancouver Island became part of the colony of British Columbia, Victoria became the united colony's capital. In 1871, British Columbia became the sixth province of Canada, its Latin motto is Splendor sine occasu. The capital of British Columbia remains Victoria, the fifteenth-largest metropolitan region in Canada, named for Queen Victoria, who ruled during the creation of the original colonies; the largest city is Vancouver, the third-largest metropolitan area in Canada, the largest in Western Canada, the second-largest in the Pacific Northwest. In October 2013, British Columbia had an estimated population of 4,606,371; the province is governed by the British Columbia New Democratic Party, led by John Horgan, in a minority government with the confidence and supply of the Green Party of British Columbia. Horgan became premier as a result of a no-confidence motion on June 29, 2017. British Columbia evolved from British possessions that were established in what is now British Columbia by 1871.
First Nations, the original inhabitants of the land, have a history of at least 10,000 years in the area. Today there are few treaties, the question of Aboriginal Title, long ignored, has become a legal and political question of frequent debate as a result of recent court actions. Notably, the Tsilhqot'in Nation has established Aboriginal title to a portion of their territory, as a result of the 2014 Supreme Court of Canada decision in Tsilhqot'in Nation v British Columbia; the province's name was chosen by Queen Victoria, when the Colony of British Columbia, i.e. "the Mainland", became a British colony in 1858. It refers to the Columbia District, the British name for the territory drained by the Columbia River, in southeastern British Columbia, the namesake of the pre-Oregon Treaty Columbia Department of the Hudson's Bay Company. Queen Victoria chose British Columbia to distinguish what was the British sector of the Columbia District from the United States, which became the Oregon Territory on August 8, 1848, as a result of the treaty.
The Columbia in the name British Columbia is derived from the name of the Columbia Rediviva, an American ship which lent its name to the Columbia River and the wider region. British Columbia is bordered to the west by the Pacific Ocean and the American state of Alaska, to the north by Yukon Territory and the Northwest Territories, to the east by the province of Alberta, to the south by the American states of Washington and Montana; the southern border of British Columbia was established by the 1846 Oregon Treaty, although its history is tied with lands as far south as California. British Columbia's land area is 944,735 square kilometres. British Columbia's rugged coastline stretches for more than 27,000 kilometres, includes deep, mountainous fjords and about 6,000 islands, most of which are uninhabited, it is the only province in Canada. British Columbia's capital is Victoria, located at the southeastern tip of Vancouver Island. Only a narrow strip of Vancouver Island, from Campbell River to Victoria, is populated.
Much of the western part of Vancouver Island and the rest of the coast is covered by temperate rainforest. The province's most populous city is Vancouver, at the confluence of the Fraser River and Georgia Strait, in the mainland's southwest corner. By land area, Abbotsford is the largest city. Vanderhoof is near the geographic centre of the province; the Coast Mountains and the Inside Passage's many inlets provide some of British Columbia's renowned and spectacular scenery, which forms the backdrop and context for a growing outdoor adventure and ecotourism industry. 75% of the province is mountainous. The province's mainland away from the coastal regions is somewhat moderated by the Pacific Ocean. Terrain ranges from dry inland forests and semi-arid valleys, to the range and canyon districts of the Central and Southern Interior, to boreal forest and subarctic prairie in the Northern Interior. High mountain regions both north and south subalpine climate; the Okanagan area, extending from Vernon to Osoyoos at the United States border, is one of several wine and cider-produci
A summit is a point on a surface, higher in elevation than all points adjacent to it. The topographic terms acme, apex and zenith are synonymous; the term top is used only for a mountain peak, located at some distance from the nearest point of higher elevation. For example, a big massive rock next to the main summit of a mountain is not considered a summit. Summits near a higher peak, with some prominence or isolation, but not reaching a certain cutoff value for the quantities, are considered subsummits of the higher peak, are considered part of the same mountain. A pyramidal peak is an exaggerated form produced by ice erosion of a mountain top. Summit may refer to the highest point along a line, trail, or route; the highest summit in the world is Everest with height of 8844.43 m above sea level. The first official ascent was made by Sir Edmund Hillary, they reached the mountain`s peak in 1953. Whether a highest point is classified as a summit, a sub peak or a separate mountain is subjective; the UIAA definition of a peak is.
Otherwise, it's a subpeak. In many parts of the western United States, the term summit refers to the highest point along a road, highway, or railroad. For example, the highest point along Interstate 80 in California is referred to as Donner Summit and the highest point on Interstate 5 is Siskiyou Mountain Summit. A summit climbing differs from the common mountaineering. Summit expedition requires: 1+ year of training, a good physical shape, a special gear. Although a huge part of climber’s stuff can be left and taken at the base camps or given to porters, there is a long list of personal equipment. In addition to common mountaineers’ gear, Summit climbers need to take Diamox and bottles of oxygen. There are special requirements for crampons, ice axe, rappel device, etc. Geoid Hill – Landform that extends above the surrounding terrain Nadir Summit accordance Peak finder Summit Climbing Gear List
The Bendor Range is a small but once-famous subrange of the Pacific Ranges of the Coast Mountains, about It is 7,000 square kilometres in area and about 40 km long and about 18 km at its widest. It lies between Anderson Lake on the southeast and the Carpenter Lake Reservoir or the Bridge River Power Project on the north, with the gold-rich valley of Cadwallader Creek on its southwest; the range's western flank is the site of a series of now-semi-abandoned mining towns. One of these, Bralorne, is among the deepest mines in Canada and in its heyday was the third-richest gold mine in the world, its shafts plunge a mile beneath sea level under the range. The name "Bendor" is believed by some locally to be a Gaelic-French hybrid - ben d'or - mountain of gold - and while it does mean that, more or less, the name was conferred in honour of Bend Or, a famous racehorse of the 1890s; the range has only a few small icefields, but a number of high and difficult peaks. The highest is Whitecap Mountain 2918 m, visible from the Lillooet end of Seton Lake but, as it is located near the heart of the range, invisible from the towns and lakes around its perimeter.
At the northwest of the range, but invisible from the towns below because of the terrain of its flanks, is Mount Truax 2870 m. East of it are Mount Williams 2775 m and Mount Bobb 2821 m. Note: some classification systems assign the Bendor to the Chilcotin Ranges subgrouping of the Pacific Ranges, but this is incorrect as it is on the south side of the Bridge River, the limit of the Chilcotin Ranges. "Bendor Range". BC Geographical Names. Bridge River-Lillooet Country Archive Bendor Range entry in the Canadian Mountain Encyclopedia
Mount Cayley massif
The Mount Cayley massif is a group of mountains in the Pacific Ranges of southwestern British Columbia, Canada. Located 45 km north of Squamish and 24 km west of Whistler, the massif resides on the edge of the Powder Mountain Icefield, it consists of an eroded but active stratovolcano that towers over the Cheakamus and Squamish river valleys. All major summits have elevations greater than 2,000 m, Mount Cayley being the highest at 2,385 m; the surrounding area has been inhabited by indigenous peoples for more than 7,000 years while geothermal exploration has taken place there for the last four decades. Part of the Garibaldi Volcanic Belt, the Mount Cayley massif was formed by subduction zone volcanism along the western margin of North America. Eruptive activity began about 4,000,000 years ago and has since undergone three stages of growth, the first two of which built most of the massif; the latest eruptive period occurred sometime in the last 400,000 years with lesser activity continuing into the present day.
Future eruptions are to threaten neighbouring communities with pyroclastic flows and floods. To monitor this threat, the volcano and its surroundings are monitored by the Geological Survey of Canada. Eruption impact would be a result of the concentration of vulnerable infrastructure in nearby valleys; the massif resides in the middle of a north–south trending zone of volcanism called the Mount Cayley volcanic field. It consists predominantly of volcanoes that formed subglacially during the Late Pleistocene age, such as Pali Dome, Slag Hill, Ring Mountain and Ember Ridge, but activity continued at Pali Dome and Slag Hill into the Holocene epoch; the Mount Cayley volcanic field is part of the Garibaldi Volcanic Belt, which in turn represents a northern extension of the Cascade Volcanic Arc. Volcanism of the Cascade Arc is a result of the Juan de Fuca Plate sliding under the North American Plate at the Cascadia subduction zone. Three main summits comprise the Mount Cayley massif; the highest and northernmost is Mount Cayley with an elevation of 2,385 m.
Its northeastern flank abuts the southern end of the Powder Mountain Icefield. This is a 9 km long and 5 km wide irregularly-shaped glacier that trends to the northwest. Just southwest of Mount Cayley lies 2,341 m in elevation, it contains a jagged summit ridge of many slender rock pinnacles, the largest of, known as the Vulcan's Thumb. Wizard Peak with an elevation of 2,240 m is east of Pyroclastic Peak and is the lowest of the three main summits; as a stratovolcano, the Mount Cayley massif is built up of solidified lava and ash from successive volcanic eruptions. It is predominantly dacitic in composition, although rhyodacite is common, its original and current volumes remain uncertain. It may have had a volume as large as 13 km3, but erosion has since reduced it to glacially eroded crags; the modern volcano has an estimated volume of 8 km3 and is only a modest fraction of its total output of silicic eruptive products. It has a proximal relief of 550 m and a draping relief of 2,070 m, with a nearly vertical cliff more than 500 m high above the Turbid Creek valley.
Turbid Creek, Dusty Creek, Avalanche Creek and Shovelnose Creek flow from the slopes of the Mount Cayley massif. Deep seismic profiling 12.5 to 13 km below the massif has identified a large bright spot, a reflector interpreted to be a mid-crustal magma chamber or body of hot rock. Similar mid-crustal reflectors have been identified under subduction zone volcanoes in Japan; the Mount Cayley massif has experienced volcanic eruptions sporadically for the last 4,000,000 years, making it one of the most persistent eruptive centres in the Garibaldi Volcanic Belt. Three primary eruptive stages in the history of the massif have been identified; the Mount Cayley and Vulcan's Thumb stages occurred between 4,000,000 and 600,000 years ago with the construction of the stratovolcano and plug domes. A 300,000-year-long period of quiescence followed, during which prolonged erosion destroyed much of the original volcanic structure; this was followed by the third and final Shovelnose stage about 300,000 to 200,000 years ago with the emplacement of parasitic lava domes and flows.
Although one of the Shovelnose domes has been potassium-argon dated at 310,000 years old, this date may be in error from excess argon. The Shovelnose stage rocks could be much younger less than 15,000 years old. Eruptions during the three stages produced volcanic rocks of felsic and intermediate compositions, including andesite and rhyodacite; the lack of evidence for volcano-ice interactions at the Mount Cayley massif implies that all eruptive stages most took place prior to glacial periods. This contrasts with many neighbouring volcanoes, which contain abundant volcanic glass and fine-scale columnar jointing from contact with ice during eruptions. Initial volcanic activity of the Mount Cayley massif 4,000,000 years ago corresponded with changes to the regional plate tectonics; this involved the separation of the Explorer and Juan de Fuca plates off the British Columbia Coast, which had some significant ramifications for regional geologic evolution. After this reorganization ceased, volcanism shifted westward from the Pemberton Volcanic Belt to establish the younger and active Garibaldi Volcanic Belt.
The westward shift in volcanism may have been related to steepening of the Juan de Fuca slab after the formation of the Explorer Plate. The early Mount Cayley stage was characterized by the eruption of felsic lava flows and pyroclastic rocks onto a crystalline bas