Canadian Cascade Arc
The Canadian Cascade Arc, 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, the southern end of the Canadian Cascades begin at the Canada–United States border. However, the boundaries of the northern end are not precisely known. 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, over the last 29 million years, the Canadian Cascade Arc has been erupting a chain of volcanoes along the British Columbia Coast. At least four volcanic zones in British Columbia are related to Cascade Arc volcanism and this includes a large volcanic plateau in The Interior and three linear volcanic belts on The Coast.
They were formed during different geological periods, separated by millions of years, the youngest of the three belts has been sporadically active over the last 4. 0–3.0 million years, with the latest eruption having taken place possibly in the last 1,000 years. About 2,350 years ago, an explosive eruption occurred. This is recognized as the largest volcanic eruption throughout Canada within the last 10,000 years, in historical times, the Canadian Cascade Arc has been considerably less active than the American portion of the volcanic arc. It has no records of historical eruptions, the volcanic arc poses a threat to the surrounding region. Any volcanic hazard—ranging from landslides to eruptions—could pose a significant risk to humans, even though there are no historical eruptions in the Canadian Cascade Arc, eruptive activity is very likely to resume, if this were to happen, relief efforts would be quickly organized. Teams such as the Interagency Volcanic Event Notification Plan are prepared to notify people threatened by volcanic eruptions, the Cascade Arc was originally created by subduction of the now vanished Farallon Plate at the Cascadia subduction zone.
After 28 million years ago, the Farallon Plate segmented to form the Juan de Fuca Plate, in the last few million years, volcanism has declined along the volcanic arc. The probable explanation lies in the rate of convergence between the Juan de Fuca and North American plates and these two tectonic plates currently converge 3 cm to 4 cm per year. This is only half the rate of convergence from seven million years ago. Because of the large 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 roughly 500 years, during these periods, stress builds up on the interface between the plates and causes uplift of the North American margin. When the plate finally slips, the 500 years of stored energy are released in a massive earthquake, the most recent, the 1700 Cascadia earthquake, was recorded in the oral traditions of the First Nations people on Vancouver Island
This article is for the mountain range in Canada. For the French island in the Mediterranean, see Bendor and 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 ranges 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 and its shafts plunge a mile beneath sea level under the range, starting at 3500 above. The range has only a few small icefields, but a number of extremely high, at the northwest of the range, but mostly 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
Pemberton, British Columbia
Pemberton is a village municipality north of Whistler in the Pemberton Valley of British Columbia in Canada, with a population of 2,192. Until the 1960s the village could be reached only by train, British Columbia, Canada, is a small village located in the Coast Mountains,100 miles north of Vancouver. Pemberton has a population of approximately 2,500 people, until the early 1960s, when Highway 99 was built, Pemberton was accessible only by train and the population was under 200 people. Pemberton is known as the Seed Potato Capital of the World due to its production of seed potatoes. The local economy is dependent on logging and tourism. Mt. Currie rises to the south, at 8,500 ft, Forest service roads brought forest service campsites, trail heads, view points and access to many of the lakes and hot springs in the area. Meager Creek Hot Springs accessible, but not formally reopened on Meager Creek west on South Creek Forest Service Road and 9.5 km trail on foot. Pebble Creek Hot Springs or Keyhole Hot Springs was formerly known as Boulder Creek Hot Springs west on Upper Lilloeet Forest Service Road 1.5 km trail on foot.
Skookumchuck Hot Springs/ Saint Agnes Well former names - reverted / renamed Tsek Hot Spring - east on In-SHUCK-ch Forest Service Road, sloquet Hot Springs farther east on In-SHUCK-ch Forest Service Road. The climate of Pemberton is very warm and dry in the summer and mild, Pemberton is an ecologically complex and diverse zone which is referred to as the Coast-Interior Transition zone. High summer temperatures and the pronounced water deficits during the season are the norm. Frances Ermantinger arrived by way of Seton lake and Anderson Lake, in all likelihood both men were searching for a safe route for fur brigades from Kamloops and Fort Langley, for a route to bypass the lower Fraser River canyons. By then, as of the Oregon Treaty, the lower Columbia River, the link with the Interior, was American. The men traveled on foot and by canoe from Kamloops to the end of the lake named for the leader. The exploration party continued by what Anderson described as a “very good trail”, the next day, following the Birkenhead River, they reached the Mount Currie area by late afternoon.
In 1858 the Fraser Canyon Gold Rush began and some 30,000 miners began the trek through traditional Lilwat and upper Statimc territory to the goldfields at Lillooet, known as Cayoosh Flat. Many miners who reached the goldfields in the summer of 1858 intended to stay the winter, the miners needed food and that food had to be transported to regions above the lower canyons of the Fraser, where there were no roads. Because he knew that twelve years earlier A. C, the total length of trail would be just over sixty-eight miles, the total length of all lakes nearly fifty-six miles
The mountain ranges name derives from its proximity to the sea coast, and is often referred to as the Coast Range. The range includes volcanic and non-volcanic mountains and the ice fields of the Pacific and Boundary Ranges. The Coast Mountains are approximately 1,600 kilometres long and average 300 kilometres in width, covered in dense temperate rainforest on its western exposures, the range rises to heavily glaciated peaks, including the largest temperate-latitude ice fields in the world. On its eastern flanks, the tapers to the dry Interior Plateau. The Coast Mountains are part of the Pacific Ring of Fire—the ring of volcanoes, the Coast Mountains consists of three subdivisions known as the Pacific Ranges, the Kitimat Ranges, and the Boundary Ranges. The Pacific Ranges are the southernmost subdivision of the Coast Mountains, included in this subdivision is four of the five major coastal icecaps in the southern Coast Mountains. These are the largest temperate-latitude icecaps in the world and fuel a number of major rivers, other than logging and a large ski resort at the resort town of Whistler, most of the land in the range is completely undeveloped.
Mount Waddington, the highest mountain of the Coast Mountains, lies in the Waddington Range of the Pacific Ranges, just north of the Pacific Ranges lies the central subdivision known as the Kitimat Ranges. This subdivision extends from the Bella Coola River and Burke Channel in the south to the Nass River in the north, the third and northernmost subdivision of the Coast Mountains is the Boundary Ranges, extending from the Nass River in the south to the Kelsall River in the north. This precipitation is among the heaviest in North America, the eastern slopes are relatively dry and less steep and protect the British Columbia Interior from the Pacific weather systems, resulting in dry warm summers and dry cold winters. Beyond the eastern slopes is a 154,635 km2 plateau occupying the southern, included within the Interior Plateau is a coalescing series of layered flood basalt lava flows. These sequences of fluid volcanic rock cover about 25,000 km2 of the Interior Plateau and have a volume of about 1,800 km3, the Coast Mountains consists of deformed igneous and metamorphosed structurally complex pre-Tertiary rocks.
These originated in locations around the globe, the area is built of several different terranes of different ages with a broad range of tectonic origins. Further north the northwesterly structural trend of the Coast Mountains lies partly in a continental rift responsible for the creation of several volcanoes. These volcanoes form part of the Northern Cordilleran Volcanic Province, the most volcanically active area in Canada, the first event began 130 million years ago when a group of active volcanic islands approached a pre-existing continental margin and coastline of North America. This subduction zone eventually jammed and shut down completely 115 million years ago, ending the Omineca Arc, compression resulting from this collision crushed and folded rocks along the old continental margin. The Insular Belt welded onto the continental margin by magma that eventually cooled to create a large mass of igneous rock. This large mass of rock is the largest granite outcropping in North America
A stratovolcano, known as a composite volcano, is a conical volcano built up by many layers of hardened lava, tephra and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a profile and periodic explosive eruptions and effusive eruptions. The lava flowing from stratovolcanoes typically cools and hardens before spreading far due to high viscosity, the magma forming this lava is often felsic, having high-to-intermediate levels of silica, with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows are uncommon, but have travelled as far as 15 km, stratovolcanoes are sometimes called composite volcanoes because of their composite layered structure built up from sequential outpourings of eruptive materials. They are among the most common types of volcanoes, in contrast to the less common shield volcanoes, two famous stratovolcanoes are Krakatoa, best known for its catastrophic eruption in 1883 and Vesuvius, famous for its destruction of the towns Pompeii and Herculaneum in 79 CE.
Both eruptions claimed thousands of lives, in modern times, Mount Saint Helens and Mount Pinatubo have erupted catastrophically. Existence of stratovolcanoes has not been proved on other bodies of the solar system with one exception. Their existence was suggested for some isolated massifs on Mars, e. g. Zephyria Tholus, stratovolcanoes are common at subduction zones, forming chains along plate tectonic boundaries where oceanic crust is drawn under continental crust or another oceanic plate. The release of water from hydrated minerals is termed dewatering, and occurs at pressures and temperatures for each mineral. The magma rises through the crust, incorporating silica-rich crustal rock, when the magma nears the top surface, it pools in a magma chamber under or within the volcano. There, the low pressure allows water and other volatiles dissolved in the magma to escape from solution, as occurs when a bottle of carbonated water is opened. Once a critical volume of magma and gas accumulates, the obstacle of the cone is overcome.
In recorded history, explosive eruptions at subduction zone volcanoes have posed the greatest hazard to civilizations. Subduction-zone stratovolcanoes, such as Mount St. Helens, Mount Etna and Mount Pinatubo, typically erupt with explosive force, as a consequence, the tremendous internal pressures of the trapped volcanic gases remain in the pasty magma. Following the breaching of the chamber, the magma degasses explosively. The gases and water out with speed and force. Since 1600 CE, nearly 300,000 people have killed by volcanic eruptions. Most deaths were caused by flows and mudflows, deadly hazards that often accompany explosive eruptions of subduction-zone stratovolcanoes
A summit is a point on a surface that is higher in elevation than all points immediately adjacent to it. Mathematically, a summit is a maximum in elevation. The topographic terms acme, apex and zenith are synonymous, the UIAA definition is that a summit is independent if it has a prominence of 30 metres or more, it is a mountain if it has a prominence of at least 300 metres. This can be summarised as follows, 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. In many parts of the western United States, the term refers to the highest point along a road, highway. For example, the highest point along Interstate 80 in California is referred to as Donner Summit while the highest point on Interstate 5 is Siskiyou Mountain Summit, geoid Hill List of highest mountains Maxima and minima Nadir Summit accordance Peak finder
Debris flows descending steep channels commonly attain speeds that surpass 10 meters per second, although some large flows can reach speeds that are much greater. Debris flows with volumes ranging up to about 100,000 cubic meters occur frequently in mountainous regions worldwide, the largest prehistoric flows have had volumes exceeding 1 billion cubic meters. As a result of their high sediment concentrations and mobility, debris flows can be very destructive, notable debris-flow disasters of the twentieth century involved more than 20,000 fatalities in Armero, Colombia in 1985 and tens of thousands in Vargas State, Venezuela in 1999. Debris flows have volumetric sediment concentrations exceeding about 40 to 50%, by definition, “debris” includes sediment grains with diverse shapes and sizes, commonly ranging from microscopic clay particles to great boulders. Media reports often use the term mudflow to describe debris flows, on Earths land surface, mudflows are far less common than debris flows.
However, underwater mudflows are prevalent on submarine continental margins, where they may spawn turbidity currents, Debris flows in forested regions can contain large quantities of woody debris such as logs and tree stumps. Sediment-rich water floods with solid concentrations ranging from about 10 to 40% behave somewhat differently from debris flows and are known as hyperconcentrated floods, normal stream flows contain even lower concentrations of sediment. Debris flows can be triggered by rainfall or snowmelt, by dam-break or glacial outburst floods. Debris flows can be more frequent following forest and brush fires, in Japan a large debris flow or landslide is called yamatsunami, literally mountain tsunami. Debris flows are accelerated downhill by gravity and tend to follow steep mountain channels that debouche onto alluvial fans or floodplains, the front, or head of a debris-flow surge often contains an abundance of coarse material such as boulders and logs that impart a great deal of friction.
Trailing behind the high-friction flow head is a lower-friction, mostly liquefied flow body that contains a percentage of sand, silt. These fine sediments help retain high pore-fluid pressures that enhance debris-flow mobility, in some cases the flow body is followed by a more watery tail that transitions into a hyperconcentrated stream flow. Debris flows tend to move in a series of pulses, or discrete surges, wherein each pulse or surge has a head, body. Debris-flow deposits are readily recognizable in the field and they make up significant percentages of many alluvial fans and debris cones along steep mountain fronts. Lateral levees can confine the paths of ensuing debris flows, through dating of trees growing on such deposits, the approximate frequency of destructive debris flows can be estimated. This is important information for development in areas where debris flows are common. Ancient debris-flow deposits that are exposed only in outcrops are more difficult to recognize and this poor sorting of sediment grains distinguishes debris-flow deposits from most water-laid sediments.
Other geological flows that can be described as debris flows are typically given more specific names, the word lahar is of Indonesian origin, but is now routinely used by geologists worldwide to describe volcanogenic debris flows
Canada is a country in the northern half of North America. Canadas border with the United States is the worlds longest binational land border, the majority of the country has a cold or severely cold winter climate, but southerly areas are warm in summer. Canada is sparsely populated, the majority of its territory being dominated by forest and tundra. It is highly urbanized with 82 per cent of the 35.15 million people concentrated in large and medium-sized cities, One third of the population lives in the three largest cities, Toronto and Vancouver. Its capital is Ottawa, and other urban areas include Calgary, Quebec City, Winnipeg. Various aboriginal peoples had inhabited what is now Canada for thousands of years prior to European colonization. Pursuant to the British North America Act, on July 1,1867, the colonies of Canada, New Brunswick and this began an accretion of provinces and territories to the mostly self-governing Dominion to the present ten provinces and three territories forming modern Canada.
With the Constitution Act 1982, Canada took over authority, removing the last remaining ties of legal dependence on the Parliament of the United Kingdom. Canada is a parliamentary democracy and a constitutional monarchy, with Queen Elizabeth II being the head of state. The country is officially bilingual at the federal level and it is one of the worlds most ethnically diverse and multicultural nations, the product of large-scale immigration from many other countries. Its advanced economy is the eleventh largest in the world, relying chiefly upon its abundant natural resources, Canadas long and complex relationship with the United States has had a significant impact on its economy and culture. Canada is a country and has the tenth highest nominal per capita income globally as well as the ninth highest ranking in the Human Development Index. It ranks among the highest in international measurements of government transparency, civil liberties, quality of life, economic freedom, Canada is an influential nation in the world, primarily due to its inclusive values, years of prosperity and stability, stable economy, and efficient military.
While a variety of theories have been postulated for the origins of Canada. In 1535, indigenous inhabitants of the present-day Quebec City region used the word to direct French explorer Jacques Cartier to the village of Stadacona, from the 16th to the early 18th century Canada referred to the part of New France that lay along the St. Lawrence River. In 1791, the area became two British colonies called Upper Canada and Lower Canada collectively named The Canadas, until their union as the British Province of Canada in 1841. Upon Confederation in 1867, Canada was adopted as the name for the new country at the London Conference. The transition away from the use of Dominion was formally reflected in 1982 with the passage of the Canada Act, that year, the name of national holiday was changed from Dominion Day to Canada Day
Types of volcanic eruptions
Several types of volcanic eruptions—during which lava 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. There are three different types of eruptions, the most well-observed are magmatic eruptions, which involve the decompression of gas within magma that propels it forward. Phreatomagmatic eruptions are another type of eruption, driven by the compression of gas within magma. Within these wide-defining eruptive types are several subtypes, the weakest are Hawaiian and submarine, followed by Vulcanian and Surtseyan. The stronger eruptive types are Pelean eruptions, followed by Plinian eruptions and phreatic eruptions are defined by their eruptive mechanism, and vary in strength.
An important measure of strength is Volcanic Explosivity Index, an order of magnitude scale ranging from 0 to 8 that often correlates to eruptive types. Explosive eruptions are characterized by gas-driven explosions that propels magma and tephra, effusive eruptions, are characterized by the outpouring of lava without significant explosive eruption. Volcanic eruptions vary widely in strength, on the one extreme there are effusive Hawaiian eruptions, which are characterized by lava fountains and fluid lava flows, which are typically not very dangerous. On the other extreme, Plinian eruptions are large, volcanoes are not bound to one eruptive style, and frequently display many different types, both passive and explosive, even the span of a single eruptive cycle. Volcanoes do not always erupt vertically from a crater near their peak. Some volcanoes exhibit lateral and fissure eruptions, many Hawaiian eruptions start from rift zones, and some of the strongest Surtseyan eruptions develop along fracture zones.
Scientists believed that pulses of magma mixed together in the chamber before climbing upward—a process estimated to several thousands of years. But Columbia University volcanologists found that the eruption of Costa Rica’s Irazú Volcano in 1963 was likely triggered by magma that took a route from the mantle over just a few months. The volcanic explosivity index is a scale, from 0 to 8 and it is used by the Smithsonian Institutions Global Volcanism Program in assessing the impact of historic and prehistoric lava flows. It operates in a way similar to the Richter scale for earthquakes, the vast majority of volcanic eruptions are of VEIs between 0 and 2. Volcanic eruptions by VEI index Magmatic eruptions produce juvenile clasts during explosive decompression from gas release, Hawaiian eruptions are a type of volcanic eruption, named after the Hawaiian volcanoes with which this eruptive type is hallmark. Hawaiian eruptions are the calmest types of events, characterized by the effusive eruption of very fluid basalt-type lavas with low gaseous content
A rockfall or rock-fall refers to quantities of rock falling freely from a cliff face. The term is used for collapse of rock from roof or walls of mine or quarry workings. Alternatively, a rockfall is the downward motion of a detached block or series of blocks with a small volume involving free falling, rolling. The mode of failure differs from that of a rockslide, a tree may be blown by the wind, and this causes a pressure at the root level and this loosens rocks and can trigger a fall. The pieces of rock collect at the bottom creating a talus or scree, rocks falling from the cliff may dislodge other rocks and serve to create another mass wasting process, for example an avalanche. A cliff that has favorable geology to a rockfall may be said to be incompetent, one that is not favorable to a rockfall, which is better consolidated, may be said to be competent. Typically, rockfall events are mitigated in one of two ways, either by passive mitigation or active mitigation, the rockfall still takes place but an attempt is made to control the outcome.
In contrast, active mitigation is carried out in the initiation zone, some examples of these measures are rock bolting, slope retention systems, etc. Other active measures might be by changing the geographic or climatic characteristics in the zone, e. g. altering slope geometry, dewatering the slope, revegetation. Design guides of passive measures have been proposed by Ritchie, Pierson et al, the effect of rockfalls on trees can be seen in several ways. The tree roots may rotate, via the energy of the rockfall. The tree may move via the application of translational energy, and lastly deformation may occur, either elastic or plastic. Dendrochronology can reveal a past impact, with missing tree rings, as the tree rings grow around and close over a gap, a macroscopic section can be used for dating of avalanche and rockfall events. Earthquake Kinetic energy Landslide Potential energy Protection forest Rockslide Slope stability SMR classification Q-slope
Traditional definitions require a topographic map to show both natural and man-made features. A topographic map is published as a map series, made up of two or more map sheets that combine to form the whole map. A contour line is a line connecting places of equal elevation, however, in the vernacular and day to day world, the representation of relief is popularly held to define the genre, such that even small-scale maps showing relief are commonly called topographic. The study or discipline of topography is a broader field of study. Topographic maps are based on topographical surveys, performed at large scales, these surveys are called topographical in the old sense of topography, showing a variety of elevations and landforms. This is in contrast to older cadastral surveys, which primarily show property, the first multi-sheet topographic map series of an entire country, the Carte géométrique de la France, was completed in 1789. Topographic surveys were prepared by the military to assist in planning for battle, as such, elevation information was of vital importance.
As they evolved, topographic map series became a resource in modern nations in planning infrastructure. Excluding borders, each sheet was 44 cm high and up to 66 cm wide, although the project eventually foundered, it left an indexing system that remains in use. TIGER was developed in the 1980s and used in the 1990, digital elevation models were compiled, initially from topographic maps and stereographic interpretation of aerial photographs and from satellite photography and radar data. Since all these were government projects funded with taxes and not classified for security reasons. Initial applications were mostly professionalized forms such as innovative surveying instruments, by the mid-1990s, increasingly user-friendly resources such as online mapping in two and three dimensions, integration of GPS with mobile phones and automotive navigation systems appeared. As of 2011, the future of standardized, centrally printed topographical maps is left somewhat in doubt, the various features shown on the map are represented by conventional signs or symbols.
For example, colors can be used to indicate a classification of roads and these signs are usually explained in the margin of the map, or on a separately published characteristic sheet. Topographic maps are commonly called contour maps or topo maps. In the United States, where the national series is organized by a strict 7. 5-minute grid. Topographic maps conventionally show topography, or land contours, by means of contour lines, contour lines are curves that connect contiguous points of the same altitude. In other words, every point on the line of 100 m elevation is 100 m above mean sea level