An ice-marginal lava flow is a lava flow that comes into direct contact with a glacier or the margins of a large ice sheet. As the lava reaches the margins of an ice sheet, the front of the lava flow cools very quickly to form a barrier. Behind this barrier, the lava begins to pool, ceasing the contact between the hot lava and cold ice. The barrier is left behind as the ice retreats, leaving a thick lava front, which is in the form of a large, steep and unstable cliff face. [1]
The Barrier in British Columbia, Canada is a natural lava dam that formed when Mount Price produced a lava flow that travelled down the Rubble Creek valley and met the Cordilleran Ice Sheet about 13,000 years ago. [2] Two lakes behind the lava dam, Garibaldi Lake and Lesser Garibaldi Lake, formed after meltwater pooled behind the lava flow wall. The vertical slabs of lava that make up The Barrier occasionally collapse to form massive rock avalanches that travel down the valley toward local residences. The biggest threat posed by The Barrier is a complete collapse of the lava dam due to volcanic activity or erosion. In the late 1800s, a debris flow from The Barrier created a large boulder field which gave Rubble Creek its name. [2] Conditions are so unstable that the area directly below The Barrier is considered uninhabitable and dangerous to human life. [3]
A second example of ice-marginal lava flows can be found at Hoodoo Mountain, a flat-topped stratovolcano in British Columbia, Canada. [4] The volcano contains 50 to 200 m (160 to 660 ft) high cliffs that formed as a result of lava erupting subglacially in the last 100,000 years. As lava poured down the slope, the lava came into contact with glacial ice that completely surrounded the volcano and cooled very quickly, forming a barrier around the entire volcano. Scientists are able to diagnose these lava cliff formations as a result of ice-marginal lava flows due to specific features such as the glassy texture of the lava and columnar jointing, which are evidence of fairly quick cooling of an erupted lava flow. [5] The lava cooled, pooled and as the glacial ice receded, it left behind massive lava cliffs.
Mount Ruapehu, the tallest mountain on the North Island of New Zealand, is a massive stratovolcano that has also produced ice-marginal lava flows. These flows are a keystone in Ruapehu's history and are well exposed in the Wahainoa Lava Formation. They display characteristic columnar jointing and massively thick lava barriers. Scientists have determined through geochronology that between 15,000 and 51,000 years ago, the volcano erupted lava flows that came into contact with the surrounding valley floor glaciers and built up the enormous lava formations we see today. Using the eruption age and the ice-marginal lava flow data, scientists can gather when glaciers dominated Ruapehu, how high an elevation the glaciers reached, which was about 1,300 m (4,300 ft) above sea level, and can use glaciovolcanism as a proxy to reconstruct the paleoclimate of about 41-51 thousand and 15-27 thousand years ago. [6]
Mount Ruapehu is an active stratovolcano at the southern end of the Taupō Volcanic Zone in New Zealand. It is 23 kilometres (14 mi) northeast of Ohakune and 23 km (14 mi) southwest of the southern shore of Lake Taupō, within Tongariro National Park. The North Island's major ski resorts and only glaciers are on its slopes.
Landforms are categorized by characteristic physical attributes such as their creating process, shape, elevation, slope, orientation, rock exposure, and soil type.
Mount Garibaldi is a potentially active stratovolcano in the Sea to Sky Country of British Columbia, 80 km (50 mi) north of Vancouver, British Columbia, Canada. Located in the southernmost Coast Mountains, it is one of the most recognized peaks in the South Coast region, as well as British Columbia's best known volcano. It lies within the Garibaldi Ranges of the Pacific Ranges.
The Garibaldi Volcanic Belt is a northwest–southeast trending volcanic chain in the Pacific Ranges of the Coast Mountains that extends from Watts Point in the south to the Ha-Iltzuk Icefield in the north. This chain of volcanoes is located in southwestern British Columbia, Canada. It forms the northernmost segment of the Cascade Volcanic Arc, which includes Mount St. Helens and Mount Baker. Most volcanoes of the Garibaldi chain are dormant stratovolcanoes and subglacial volcanoes that have been eroded by glacial ice. Less common volcanic landforms include cinder cones, volcanic plugs, lava domes and calderas. These diverse formations were created by different styles of volcanic activity, including Peléan and Plinian eruptions.
The Black Tusk is a stratovolcano and a pinnacle of volcanic rock in Garibaldi Provincial Park of British Columbia, Canada. At 2,319 m (7,608 ft) above sea level, the upper spire is visible from a great distance in all directions. It is particularly noticeable from the Sea-to-Sky Highway just south of Whistler, British Columbia. Distinctive and immediately identifiable, The Black Tusk is among the best known mountains in the Garibaldi Ranges of the Coast Mountains. The volcano is part of the Garibaldi Volcanic Belt which is a segment of the Canadian Cascade Arc, but it is not within the geographic boundary of the Cascade Range.
A tuya is a flat-topped, steep-sided volcano formed when lava erupts through a thick glacier or ice sheet. They are rare worldwide, being confined to regions which were covered by glaciers and had active volcanism during the same period.
Hoodoo Mountain, less commonly called Hoodoo Volcano, is a potentially active stratovolcano in the Northern Interior of British Columbia, Canada. It is located 25 kilometres northeast of the Alaska–British Columbia border on the north side of the Iskut River opposite of the mouth of the Craig River. With a summit elevation of 1,850 metres and a topographic prominence of 900 metres , Hoodoo Mountain is one of many prominent peaks within the Boundary Ranges of the Coast Mountains. Its flat-topped summit is covered by an ice cap more than 100 metres thick and at least 3 kilometres in diameter. Two valley glaciers surrounding the northwestern and northeastern sides of the mountain have retreated significantly over the last hundred years. They both originate from a large icefield to the north and are the sources of two meltwater streams. These streams flow along the western and eastern sides of the volcano before draining into the Iskut River.
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 (93 mi) north of Vancouver at the northern end of the Pemberton Valley and reaches a maximum elevation of 2,680 m (8,790 ft). The massif is capped by several eroded volcanic edifices, including lava domes, volcanic plugs and overlapping piles of lava flows; these form at least six major summits including Mount Meager which is the second highest of the massif.
Mount Price is a small stratovolcano in the Garibaldi Ranges of the Pacific Ranges in southwestern British Columbia, Canada. It is located 10 km (6.2 mi) southeast of the abandoned settlement of Garibaldi above the eastern flank of the Cheakamus River valley. With a summit elevation of 2,049 m (6,722 ft), it rises above the surrounding landscape on the western shore of Garibaldi Lake. The mountain contains a number of subfeatures, including Clinker Peak on its western flank, which was the source of two thick lava flows between 15,000 and 8,000 years ago that ponded against glacial ice. These lava flows are structurally unstable, having produced large landslides as recently as the 1850s. A large provincial park surrounds Mount Price and other volcanoes in its vicinity.
The Garibaldi Lake volcanic field is a volcanic field, located in British Columbia, Canada. It was formed by a group of nine small andesitic stratovolcanoes and basaltic andesite vents in the scenic Garibaldi Lake area immediately north of Mount Garibaldi was formed during the late Pleistocene and early Holocene. The oldest stratovolcano, The Black Tusk, formed between about 1.3 and 1.1 million years ago (Ma). Following glacial dissection, renewed volcanism produced the lava dome and flow forming its summit. Other Pleistocene vents are located along and to the west of the Cheakamus River. Cinder Cone, to the east of The Black Tusk, produced a 9-km-long lava flow during the late Pleistocene or early Holocene.
Several types of volcanic eruptions—during which lava, tephra, and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series.
Level Mountain is a large volcanic complex in the Northern Interior of British Columbia, Canada. It is located 50 kilometres north-northwest of Telegraph Creek and 60 kilometres west of Dease Lake on the Nahlin Plateau. With a maximum elevation of 2,164 metres , it is the second-highest of four large complexes in an extensive north–south trending volcanic region. Much of the mountain is gently-sloping; when measured from its base, Level Mountain is about 1,100 metres tall, slightly taller than its neighbour to the northwest, Heart Peaks. The lower, broader half of Level Mountain consists of a shield-like structure while its upper half has a more steep, jagged profile. Its broad summit is dominated by the Level Mountain Range, a small mountain range with prominent peaks cut by deep valleys. These valleys serve as a radial drainage for several small streams that flow from the mountain. Meszah Peak is the only named peak in the Level Mountain Range.
The geology of the Pacific Northwest includes the composition, structure, physical properties and the processes that shape the Pacific Northwest region of North America. The region is part of the Ring of Fire: the subduction of the Pacific and Farallon Plates under the North American Plate is responsible for many of the area's scenic features as well as some of its hazards, such as volcanoes, earthquakes, and landslides.
The Barrier is a lava dam retaining the Garibaldi Lake system in southwestern British Columbia, Canada. It is over 300 m (980 ft) thick and about 2.4 km (1.5 mi) long where it impounds the lake.
The Mount Edziza volcanic complex is a large and potentially active north-south trending complex volcano in Stikine Country, northwestern British Columbia, Canada, located 38 kilometres (24 mi) southeast of the small community of Telegraph Creek. It occupies the southeastern portion of the Tahltan Highland, an upland area of plateau and lower mountain ranges, lying east of the Boundary Ranges and south of the Inklin River, which is the east fork of the Taku River. As a volcanic complex, it consists of many types of volcanoes, including shield volcanoes, calderas, lava domes, stratovolcanoes, and cinder cones.
The volcanic history of the Northern Cordilleran Volcanic Province presents a record of volcanic activity in northwestern British Columbia, central Yukon and the U.S. state of easternmost Alaska. The volcanic activity lies in the northern part of the Western Cordillera of the Pacific Northwest region of North America. Extensional cracking of the North American Plate in this part of North America has existed for millions of years. Continuation of this continental rifting has fed scores of volcanoes throughout the Northern Cordilleran Volcanic Province over at least the past 20 million years and occasionally continued into geologically recent times.
The Canadian Cascade Arc, also called the Canadian Cascades, is the Canadian segment of the North American Cascade Volcanic Arc. Located entirely within the Canadian province of British Columbia, it extends from the Cascade Mountains in the south to the Coast Mountains in the north. Specifically, the southern end of the Canadian Cascades begin at the Canada–United States border. However, the specific boundaries of the northern end are not precisely known and the geology in this part of the volcanic arc is poorly understood. It is widely accepted by geologists that the Canadian Cascade Arc extends through the Pacific Ranges of the Coast Mountains. However, others have expressed concern that the volcanic arc possibly extends further north into the Kitimat Ranges, another subdivision of the Coast Mountains, and even as far north as Haida Gwaii.
Glaciovolcanism is volcanism and related phenomena associated with glacial ice. The ice commonly constrains the erupted material and melts to create meltwater. Considerable melting of glacial ice can create massive lahars and glacial outburst floods known as jökulhlaups.
The Mount Cayley volcanic field (MCVF) is a remote volcanic zone on the South Coast of British Columbia, Canada, stretching 31 km (19 mi) from the Pemberton Icefield to the Squamish River. It forms a segment of the Garibaldi Volcanic Belt, the Canadian portion of the Cascade Volcanic Arc, which extends from Northern California to southwestern British Columbia. Most of the MCVF volcanoes were formed during periods of volcanism under sheets of glacial ice throughout the last glacial period. These subglacial eruptions formed steep, flat-topped volcanoes and subglacial lava domes, most of which have been entirely exposed by deglaciation. However, at least two volcanoes predate the last glacial period and both are highly eroded. The field gets its name from Mount Cayley, a volcanic peak located at the southern end of the Powder Mountain Icefield. This icefield covers much of the central portion of the volcanic field and is one of the several glacial fields in the Pacific Ranges of the Coast Mountains.
The Mount Cayley massif is a group of mountains in the Pacific Ranges of southwestern British Columbia, Canada. Located 45 km (28 mi) north of Squamish and 24 km (15 mi) west of Whistler, the massif resides on the edge of the Powder Mountain Icefield. It consists of an eroded but potentially active stratovolcano that towers over the Cheakamus and Squamish river valleys. All major summits have elevations greater than 2,000 m (6,600 ft), Mount Cayley being the highest at 2,385 m (7,825 ft). 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.