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Chapter 2

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Western University
Geography 2010A/B
Suzanne Greaves

Chapter 2: Physical Geography Physical Variations Within Canada  Physiography: study of landforms, their underlying geology, and the processes that shape these landforms: geomorphology  Physical geography has distinct and unique regional patterns across Canada  Physiographic regions are one aspect of this physical diversity  Climate, soils, and natural vegetation are another aspect and provide basis for biodiversity  Impact of human activity is changing the natural environment and, in the case of air, soil, and water pollution, there are long-term negative implications for all life forms  Physical geography has a powerful impact on Canadians by making certain areas more attractive for settlement and urban / industrial development. This relationship between the natural environment and the human world forms the basis of the core / periphery model  5 basic elements: geology, physiography (shape of the surface), climate, vegetation, soil The Nature of Landforms  Denudation: process of breaking down and removing loose material found at the surface of the earth. In this way, erosion and weathering lead to a reduction of elevation and relief in landforms o Ex: Appalachian Uplands are prime example of denudation of an ancient mountain chain  Weathering: decomposition of rock and particles in situ  Erosion: displacement of loose material by geomorphic processes such as wind, water, and ice by downward movement in response to gravity  Deposition: Deposit of material on the earth’s surface by various processes such as ice, water, and wind  Earth’s crust consists of 3 types of rocks: igneous, sedimentary, and metamorphic  Igneous Rocks: rock formed when the earth’s surface first cooled or when magma or lava that has reached the earth’s surface cool o Cools from molten state and is very hard / resisting to weathering and erosion, tends to contain minerals  Sedimentary Rocks: rocks formed from the layer accumulation in sequence of sediment deposited in the bottom of an ocean o Made up of particles of pre-existing rock, created when existing rock is exposed to process of weathering and then erosion, deposited in layers and then subjected to increasing heat / pressure and compacted together (fossil fuels, but no minerals) o Ex: Alberta Badlands are unique type of terrain found only in Alberta, horizontal in original form o Strata: layers of sedimentary rock  Metamorphic Rocks: rocks formed from igneous and sedimentary rocks by means of heat and pressure o Changes its very nature due to extreme heat and pressure, also contains minerals  Faulting: breaking of the earth’s crust as a result of differential movement of the earth’s crust (associated with earthquakes)  Folding: bending of the earth’s crust  Fault Line: crack or break in the earth’s crust  Continental Drift: movement of the earth’s crust (plate tectonics) Major Elements of North America  Canadian Shield – igneous and metamorphic, core of North American continent, oldest portion, mostly built on this stable area  Platform Rocks – sedimentary, represent the interior plains of North America (Western Canada, Southwestern Ontario & Quebec), largely undisturbed, fairly flat  Folded Belts – igneous and metamorphic, mountains o Western are youngest on the continent, still growing and getting higher, being created by collision of two plates in Earth’s crust o Appalachians are folded mountains, oldest, rounded hills covered by vegetation o Innuitian are very isolated, next to no population, covered by snow and ice – middle age  Coastal Plain – Arctic coastline near mouth of Mackenzie River, made up of material that has been weathered and eroded from Canadian Shield and mountains Physiographic Regions  Physiographic Region: large geographic area characterized by a single landform o Extends over a large, contiguous area with similar relief features o Its landform has been shaped by a common set of geomorphic processes o It possesses a common geological structure and history  Canada has 7 physiographic regions  Pleistocene Epoch: minor division of the Geological Time Chart nearly 2 million years ago. The glaciation of the Pleistocene Epoch was not continuous but consisted of several glacial advances interrupted by interglacial stages during which the ice retreated and a comparatively mild climate prevailed  Glaciation has been a dramatic force in shaping the landscape that we see in Canada  Last Glaciation was in Wisconsin were ice retreated from Southern Ontario between 10 – 15,000 years ago (went as far south as Missouri and Ohio River) o All of the surface was covered by ice – ice doesn’t always move from North to South, just depends on the condition at time o Glaciation begin when there is more snow / ice accumulating than will melt in the next season o Ice at the bottom of the pile becomes plastic in nature (more pliable)  Continental glaciers covered Eastern Canada, near the centre glaciers were 4 km thick (anything in its path is obliterated)  Glacier is a massive erosive tool carrying material away  Alpine glaciers on the West, form high up in the mountains as snow / ice accumulate those glaciers push their way down the mountain valley  Southern hemisphere has much less land than water, northern Hemisphere is where you find all the land mass  Canada experienced one of the most significant surface shaping impacts by glaciation  Largest glaciers in Canada are in the mountains of Ellesmere Island The Canadian Shield  Largest physiographic region of Canada, rugged and dotted by vast multitude of small lakes and rivers  Glacial Erosion: scraping and plucking action of moving ice on the surface of the land  Till: unsorted glacial deposits  Ice Age: geological period of severe cold accompanied by the formation of continental ice sheets  Drumlins: landforms created by the deposit of glacial till and shaped by the movement of the ice sheet  Eskers: long sinuous mounds of sand and gravel deposited on the bottom of a stream flowing under a glacier  Glacial Striations: scratches or grooves in the bedrock caused by rocks embedded in the bottom of a moving ice sheet / glacier The Cordillera  Complex region of mountains, plateaus, and valleys  North American tectonic plate slowly moved westward and collided with the Pacific plate causing the compression of sedimentary rocks into the Cordillera  Cirques: large, shallow depressions found in mountains at the head of glacial valleys that are caused by the plucking action of alpine glaciers  Arêtes: narrow serrated ridges found in glaciated mountains, form when two opposing cirques erode a mountain ridge  Glacial Troughs: U-shaped valleys carved by alpine glaciers  Along Pacific coast, tectonic plate movement continues making coast of BC vulnerable to both earthquakes and volcanic activity  Alpine glaciation has sharpened features of mountain ranges and broadened its river valleys The Interior Plains  Vast sedimentary plain, wedged between Canadian Shield and Cordillera  Most of the population lives in the southern area where a longer growing season permits grain farming and cattle ranching  Stable geological region, little effect by tectonic forces  Basins: structural depressions in sedimentary rock caused by a bending of sedimentary strata into huge bowl-like shapes  Oil and gas deposits are the result of the capture of the sun’s energy by plants and animals in earlier geologic time (non-renewable resources)  Lake Agassiz: largest glacial lake in North America that covered much of Manitoba, northwestern Ontario, and eastern Saskatchewan  Glacial Spillways: deep and wide valleys formed by the flow of massive amounts of water originating from a melting ice sheet or from water escaping from glacial lakes  Changes in elevation create 3 sub-regions within the Canadian Prairies: Manitoba Lowland, Saskatchewan Plain, and Alberta plateau  Nunataks: unglaciated area of a mountain that stood above surrounding ice sheet The Hudson Bay Lowland  Vast wetland with lack of slope and permafrost  At one time the whole area had a lower elevation than today and submerged  Lies mainly in northern Ontario, though small portions stretch into Manitoba and Quebec  Muskeg: wet marshy area found in areas of poor drainage, contains peat deposits  Tyrell Sea: prehistoric Hudson Bay as the Laurentide Ice Sheet receded. Its extent was considerably greater than that of present-day Hudson Bay because land had been depressed by the weight of the ice sheet  Because of its almost level surface and the presence of permafrost, much of the land is poorly drained  With few resources to support human activities, the region has only a handful of tiny settlements  One of the least favourably endowed physiographic regions of Canada, also youngest  Terraces: old sea beaches left after the sea has receded, old flood plains created when streams / rivers cut downward to form new and lower flood plains  Isostatic Rebound: gradual uplifting of the earth’s crust following retreat of an ice sheet that because of its weight depressed the earth’s crust  Restrained Rebound: first stage of isostatic rebound  Postglacial Uplift: gradual rising of the earth’s crust following the retreat of an ice sheet that because of its weight depressed the earth’s crust  Residual Uplift: final stages of isostatic rebound Artic Lands  Artic Circle: imaginary line that signifies the northward limit of the sun’s rays at the time of the winter solstice (sun does not rise above the horizon for one day of the year)  Complex composite of coastal plains, plateaus, and mountains  Ground is permanently frozen to great depths, never thawing, except at the surface  Permafrost: permanently frozen ground  Patterned Ground: natural arrangement of stones and pebbles in polygonal shapes found in the Artic where continuous permafrost is subjected to frost-shattering as the principal erosion process  Pingos: hills / mounds that maintain an ice core and that are found in areas of permafrost  Climate in this zone is cold and dry, no vegetation grows  Most people live in the coastal plain in the western part of the physiographic region The Appalachian Uplands  Its terrain is a mosaic of rounded uplands and narrow river valleys, with the exception of PEI  Remnants of ancient mountains that underwent a variety of weathering and erosion processes  Peneplain: more or less level land surface caused by the wearing down of ancient mountains, represents an advanced stage of erosion  Coast area has been slightly submerged, ocean waters have invaded the lower valleys creating bays / estuaries The Great Lakes-St Lawrence Lowlands  Smallest physiographic region in Canada  Landscape is flat to rolling, reflects the underlying sedimentary strata and its thin cover of glacial deposits  As a result of its southerly location, its proximity to the industrial heartland of the US, and its favourable physical setting, the region is home to Canada’s main ecumene and manufacturing core The Impact of Physiography on Human Activity  Exerted a powerful influence over the geographic pattern of early settler’s land selection o In 17 century, St Lawrence Lowland was an attractive area for the establishment of a French colony because of its agricultural lands and its accessibility by water to France. Few settlers ventured beyond this favoured area o None of the surrounding physiographic regions offered attractive land for farming o Instead, Aboriginal groups forced from their more productive land occupied these rather marginal lands where they hunted game for food and trapped furs to barter with French traders for European goods  Friction of Distance: effect of distance on spatial interaction (as distance increases, the number of spatial interactions diminishes)  Obstacles presented by physical barriers and distance have been greatly diminished in contemporary world Geographic Location  Bounded by Artic, Atlantic and Pacific oceans makes Canada a maritime nation, shipping routes are crucial  Sea Ice: ice formed from ocean water o “Fast Ice” – frozen along coasts and extend out from land o “Pack Ice” – floating, consolidated sea ice detached from land o “Ice Floe” – floating chunk of sea ice that is less than 10 km in diameter o “Ice Field” – chunk of sea ice more than 10 km in diameter  Polynyas: areas of open water surrounded by sea ice  Northwest Passage: sea route(s) through the Artic Ocean connecting the Atlantic and Pacific Oceans that can be traversed only in the summer o World’s most important ocean route between Asia and Europe if predictions of global warming resulting in more open water (ice-free Artic Ocean) are accurate  Latitude: imaginary line parallel to the equator that encircles the globe  Longitude: imaginary line that runs through both the North and South poles  As the equator represents 0 latitude, the prime meridian represents 0 longitude  Within Canada, latitude and longitude vary enormously  Variation in latitude has considerable implications for the amount of solar energy received at the surface of the earth Climate  Climate: average condition of weather in a particular area over a very long period of time (long-term average – minimum 30 years) o What we can expect while weather is what we get (refers to the current state of the atmosphere with a focus on weather conditions that affect people living in a particular place)  Lines on climate map are called isolines – joins places having the same value o Temperatures are increasing south and decreasing north (isotherms) o Differences between the line are 2.5°C – helps interpretation (lines packed together – temperature changes quickly)  Since climate is relatively stable over a long period of time, it plays a key role in the formation of soils and natural vegetation  Emergence of global pattern of soils and natural vegetation Moisture  West coast is the wettest part of the country (receives most precipitation) o In terms of annual precipitation, West coast gets the most on average from orographic rainfall  In the middle (interior plains up to where the Canadian Shield starts), one of the two driest parts in Canada o Bulk of precipitation that occurs in the middle section is convectional in nature  East is humid (adequate moisture), Eastern Canada from Manitoba- Ontario eastward has adequate moisture (supports tree formation), cyclonic storms  North is the second dry area, due to low temperature (cold air is dry air, doesn’t hold much moisture) o Area of the North is essentially cold and therefore, little precipitation falls (polar desert if you go far enough North) Temperature  Driven by latitude o Equator is 0° and poles are 90° latitude (how far from the equator) o Further from the equator = cooler it tends to be  Exceptions to this pattern are the mountains, particularly Western mountains (higher up in the mountains = colder it gets) o Temperatures might be a cooler at a certain latitude than you’d expect due to the location being high up in the mountains  East and West Coast breaks the rule of latitude as well o Moderation – presence of large body water may influence temperature up or down (moderate that temperature) o Continentality is the opposite, absence of large bodies of water so there is nothing to influence temperature Climate Controls  7 climate controls: latitude, distribution of land and water, global wind and pressure belts, ocean currents, topography, altitude, air masses  Variations in the amount of solar energy reaching different parts of the earth’s surface correspond with latitude and temperature o Lower latitudes receive more solar energy and therefore have higher temperatures than higher latitudes  Distribution of land & water leads to moderation, land heats up and cools down much more quickly than water does o As a result, water is capable of moderating temperature over and adjacent land mass o In order for the water to significantly moderate temperature, the wind has to be blowing onshore o City of Vancouver tends to have a reputation for a very mild climate, moderation of the ocean = narrow temperature range o Winnipeg is in the middle of the continent, no moderation = large annual temperature range o Winnipeg > Halifax > Vancouver  Global wind & pressure belts – prevailing winds are from the West, southern proportion  Altitude – higher up you go, the colder it’s go  Ocean Currents: o Alaska Current (warm), flowing through a relatively cold environment o Gulf Stream (warm) bringing heat from the tropics northward up the east coast o Labrador Current (cold) brings cold water down from the eastern artic  Topography – mountains can represent a physical barrier, in order to have orographic rainfall you must have physical barriers  Global circulation of air masses causes a westerly flow of air across Canada, although invasions of air masses from the Artic and the Gulf of Mexico can temporarily disrupt this general pattern of air circulation  Continental effect refers to the effect of distance from oceans on temperature and precipitation o As distance from ocean increases, the annual temperature range increases and annual amount of precipitation decreases Global Circulation System  Regional climates are controlled by the amount of solar energy absorbed by the earth and its atmosphere and then converted into heat  Low latitudes around the equator have a net surplus of energy, but in high latitudes around the North and South poles, more energy is lost through re-radiation than is received, and therefore annual average temperature are extremely low  Global Circulation System: movement of ocean currents and wind systems that redistribute energy around the world  Atmospheric circulation system travels in a west-to-east direction in the higher latitudes of the northern hemisphere, causing air masses that develop over large water bodies to bring mild and moist weather to adjacent land masses  Marine Air Masses: large homogenous bodies of air with moisture and temperature characteristics similar to the ocean where they originated. Normally moist and relatively mild in both winter and summer  Continental Air Masses: homogenous bodies of air th
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