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
The Pleistocene is the geological epoch which lasted from about 2,588,000 to 11,700 years ago, spanning the worlds most recent period of repeated glaciations. The end of the Pleistocene corresponds with the end of the last glacial period, the Pleistocene is the first epoch of the Quaternary Period or sixth epoch of the Cenozoic Era. In the ICS timescale, the Pleistocene is divided into four stages or ages, all of these stages were defined in southern Europe. In addition to this subdivision, various regional subdivisions are often used. Charles Lyell introduced the term pleistocene in 1839 to describe strata in Sicily that had at least 70% of their molluscan fauna still living today and this distinguished it from the older Pliocene Epoch, which Lyell had originally thought to be the youngest fossil rock layer. The Pleistocene has been dated from 2.588 million to 11,700 years before present and it covers most of the latest period of repeated glaciation, up to and including the Younger Dryas cold spell.
The end of the Younger Dryas has been dated to about 9640 BC, the IUGS has yet to approve a type section, Global Boundary Stratotype Section and Point, for the upper Pleistocene/Holocene boundary. The proposed section is the North Greenland Ice Core Project ice core 75°06 N 42°18 W, the lower boundary of the Pleistocene Series is formally defined magnetostratigraphically as the base of the Matuyama chronozone, isotopic stage 103. Above this point there are notable extinctions of the calcareous nanofossils, Discoaster pentaradiatus, the Pleistocene covers the recent period of repeated glaciations. The name Plio-Pleistocene has, in the past, been used to mean the last ice age. The revised definition of the Quaternary, by pushing back the date of the Pleistocene to 2.58 Ma. Pleistocene climate was marked by repeated glacial cycles in which continental glaciers pushed to the 40th parallel in some places and it is estimated that, at maximum glacial extent, 30% of the Earths surface was covered by ice.
In addition, a zone of permafrost stretched southward from the edge of the sheet, a few hundred kilometres in North America. The mean annual temperature at the edge of the ice was −6 °C, during interglacial times, such as at present, drowned coastlines were common, mitigated by isostatic or other emergent motion of some regions. The effects of glaciation were global, antarctica was ice-bound throughout the Pleistocene as well as the preceding Pliocene. The Andes were covered in the south by the Patagonian ice cap, there were glaciers in New Zealand and Tasmania. The current decaying glaciers of Mount Kenya, Mount Kilimanjaro, glaciers existed in the mountains of Ethiopia and to the west in the Atlas mountains. In the northern hemisphere, many glaciers fused into one, the Cordilleran ice sheet covered the North American northwest, the east was covered by the Laurentide
Geology of the Pacific Northwest
The geology of the Pacific Northwest includes the composition, physical properties and the processes that shape the Pacific Northwest region of the United States and Canada. The geology of the region much of the areas scenic beauty and causes periodic catastrophes. There are at least five provinces in the area, the Cascade Volcanoes, the Columbia Plateau, the North Cascades, the Coast Mountains. The Cascade Volcanoes are a volcanic region along the western side of the Pacific Northwest. The Coast Mountains and Insular Mountains are a strip of mountains along the coast of British Columbia, the geology of the Pacific Northwest is vast and confusing. Most of the region was formed about 200 million years ago as the North American Plate started to drift westward during the rupture of Pangaea. Since that date, the edge of North America has grown westward as a succession of island arcs. The Cascades Province forms a band extending from southwestern British Columbia to Northern California. Within this region, nearly 20 major volcanic centers lie in sequence like a string of explosive pearls, rising above this volcanic platform are a few strikingly large volcanoes that dominate the landscape.
The Cascade volcanoes define the Pacific Northwest section of the Ring of Fire, the Ring of Fire is known for its frequent earthquakes. The volcanoes and earthquakes arise from a source, subduction. Beneath the Cascade Volcanic Arc, an oceanic plate plunges beneath the North American Plate. As the oceanic slab sinks deep into the Earths interior beneath the continental plate, the water vapor rises into the pliable mantle above the subducting plate, causing some of the mantle to melt. This newly formed magma rises toward the Earths surface to erupt, a close-up look at the Cascades reveals a more complicated picture than a simple subduction zone. Not far off the coast of the North Pacific lies a spreading ridge, on one side of the spreading ridge new Pacific Plate crust is made, moves away from the ridge. On the other side of the ridge the Juan de Fuca. There are some features at the Cascade subduction zone. The probable explanation lies in the rate of convergence between the Juan de Fuca and North American Plates and these two plates converge at 3–4 centimeters per year at present
The Pacific Ranges are the southernmost subdivision of the Coast Mountains portion of the Pacific Cordillera. Located entirely within British Columbia, they run northwest from the lower stretches of the Fraser River to Bella Coola and Burke Channel, the Coast Mountains lie between the Interior Plateau and the Coast of British Columbia. The Pacific Ranges include four of the five major coastal icecaps in the southern Coast Mountains and these are the largest temperate-latitude icecaps in the world and fuel a number of very major rivers. One of these contains Mount Waddington, the highest summit entirely within British Columbia, within this region is Hunlen Falls, among the highest in Canada, located in Tweedsmuir South Provincial Park. Other than logging and various hydroelectric developments, and a ski resort at Whistler. The belt is the extension of the Cascade Volcanic Arc in the United States. The eruption styles in the range from effusive to explosive. Morphologically, centers include calderas, cinder cones and small isolated lava masses, due to repeated continental and alpine glaciations, many of the volcanic deposits in the belt reflect complex interactions between magma composition and changing ice configurations.
The most recent major eruption in the Garibaldi Volcanic Belt was from Mount Meager 2,350 BP. The Garibaldi Volcanic Belt contains 2 extra volcanic fields, the Franklin Glacier Volcano and the Silverthrone Caldera, the Cascadia subduction zone is a 680 mi long fault, running 50 mi off the west-coast of the Pacific Northwest from northern California to Vancouver Island. The plates move at a rate of over 0.4 inches per year at a somewhat oblique angle to the subduction zone. Unlike most subduction zones worldwide, there is no oceanic trench present along the margin in Cascadia. Instead and the wedge have been uplifted to form a series of coast ranges. A high rate of sedimentation from the outflow of the three rivers which cross the Cascade Range contributes to further obscuring the presence of a trench. However, in common with most other subduction zones, the margin is slowly being compressed. For a full listing of rivers in the Pacific Ranges, see List of rivers of the Pacific Ranges, canadian Mountain Encyclopedia article on the Pacific Ranges
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
The far southeast end of the Camelsfoot is extremely rugged, and dropping to one last point at 7000-plus before plunging into the gorge of the Fraser Canyon at Fountain, near Lillooet. For 45 km NW from there, the range is rocky and lightly forested with pine, breaking into high benchlands. The historic Empire Valley Ranch is near the mouth of Churn Creek and is protected for heritage. It is on a high side-valley above the Fraser Canyon, north of it beyond Churn Creek is the historically significant Gang Ranch, Camelsfoot Peak and the range itself take their name from an odd episode in the story of the Fraser and Cariboo Gold Rushes. Frank Laumeister, a United States veteran of the Camel Corps, bought 23 camels from the US military, which was ending their use. He used the animals to carry freight on the Douglas Road and the Old Cariboo Road from Lillooet to Fort Alexandria, after this, he finally discontinued using the camels. Horses could not stand their smell, the soft feet were hurt by the rocky soils of the BC Interior and the canyon trails.
Many escaped retirement into the wilds, the last confirmed sighting was in the Ashcroft area in 1905, possibly 1910 by some claims. Barroom stories recount sightings elsewhere in the southern Interior into the 1930s, the original Log Cabin Theatre in Lillooet, still exists today, originally was used by Laumeister for a camel barn. No one knows if the camels roamed the Camelsfoot, the new highway bridge in Lillooet is named the Bridge of the Twenty-Three Camels to commemorate their role in local history. The name of the Yalakom River is a version of the Chilcotin word for the ewe of the mountain sheep. Shulaps, the name of the range to the west of the Camelsfoot, is a version of the Chilcotin for the ram. Poison Mountains name comes from the leaching of its orebodies into local streams while Reds comes from the colour of its cuprous earth. Reds flanks show ziggurat-like scars that are evidence of the scale of ore-sampling that at one time was underway and these have never been brought forward in the public planning process, nor are they likely to be given the scope of First Nations land claims in the immediate region.
Red has a summit, French Mountain 2231 m, originally named French Bar Mountain after a rich gold-bearing bar on the Fraser just east. North of them is a remote, gentle summit known as Black Dome Mountain 2252 m, China Head 2125 m and Nine Mile Ridge 2422 m are southeast of Red and are large, wide ridges covered in meadow, Nine Mile Ridge is a protected area. The term head in 19th-century frontier usage was a synonym for mountain or ridge or headland, east of Yalakom Mountain is Hogback Mountain 2149 m, whose name is not descriptive but concerns Cheng Wons hog ranch on its shoulders from which the pigs would run wild onto the mountain. South of Hogback and Leon Creek the range becomes much more rugged as it narrows, Mount Birch 2232 m, just south of Leon Creek, is named after the Lieutenant-Governor who ran the Crown Colony of British Columbia for most of the alcoholic Frederick Seymours term as Governor
Garibaldi Volcanic Belt
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, 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 these diverse formations were created by different styles of volcanic activity, including Peléan and Plinian eruptions. Eruptions along the length of the chain have created at least three volcanic zones. The first began in the Powder Mountain Icefield 4.0 million years ago, the Mount Cayley massif began its formation during this period. These major volcanic zones lie in three segments, referred to as the northern and southern segments. Each segment contains one of the three volcanic zones. Apart from these volcanic zones, two large poorly studied volcanic complexes lie at the northern end of the Pacific Ranges, namely Silverthrone Caldera.
They are considered to be part of the Garibaldi Volcanic Belt, prior to Garibaldi Belt formation, a number of older, but related volcanic belts were constructed along the Southern Coast of British Columbia. This includes the east-west trending Alert Bay Volcanic Belt on northern Vancouver Island, the Pemberton Belt began its formation when the former Farallon Plate was subducting under the British Columbia Coast 29 million years ago during the Oligocene epoch. At this time, the portion of the Farallon Plate was just starting to subduct under the U. S. state of California. Between 18 and five years ago during the Miocene period. After this breakup, subduction of the Juan de Fuca Plate might have been coincident with the end of Vancouver Island eight million years ago during the late Miocene period. This is when the Alert Bay Belt became active, a brief interval of plate motion adjustment about 3.5 million years ago may have triggered the generation of basaltic magma along the descending plate edge.
Bedrock under the Garibaldi chain consists of granitic and dioritic rocks of the Coast Plutonic Complex and this is a large batholith complex that was formed when the Farallon and Kula plates were subducting along the western margin of the North American Plate during the Jurassic and Tertiary periods. It lies on island arc remnants, oceanic plateaus and clustered continental margins that were added along the margin of North America between the Triassic and Cretaceous periods. The Garibaldi Belt has formed in response to ongoing subduction of the Juan de Fuca Plate under the North American Plate at the Cascadia subduction zone along the British Columbia Coast. This is a 1,094 km long fault zone running 80 km off the Pacific Northwest from Northern California to southwestern British Columbia, the plates move at a relative rate of over 10 mm per year at a somewhat oblique angle to the subduction zone
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
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