Geo 2010 Ch2.docx

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Geography 2010A/B
Suzanne Greaves

Chapter 2: Canada’s Physical Base Introduction  The earth provides a wide variety of natural settings for human beings  Physical geography helps us understand the regional nature of our world  Interrelationship between physical geography and human settlement, activity, and culture  Regions with a more favorable physical base are more likely to develop into core regions, while regions with less favorable physical base turn into periphery  Canada’s ecumene—which stretches along the US border—supports this argument Physical Variation within Canada  Climate o Climate affects the shape of landforms (mountains, plateaus, and lowlands) through a variety of weathering and erosion processes o Flat to rolling topography of the prairies is different from that found in the Canadian Shield which consist of rugged, rocking, hilly terrain  Physiography: study of landforms, their underlying geology, and the processes that shape these landforms o Landforms, bodies of water, climate, soils, and natural vegetation o Regional geographers are more interested in how physical geography varies and subsequently influences human settlement of the land o Also concerned about the effect of human activities on the natural environment  E.g. land developments have reduced the size of natural habitat  Natural environment and essential role to regional geography o Physical geography has distinct and unique regional patterns across Canada o Physiographic regions are one aspect of this physical diversity o Climate, soils and natural vegetations are another aspect that provide basis for biodiversity o Impact of human activity is changing the natural environment  Air, soil, water pollution—long term negative implication for all life forms o Physical geography has a powerful impact on Canadians by making certain areas more attractive for settlement and urban/industrial development  Core/periphery model The Nature of Landforms  The surface features a variety of landforms: mountains, plateaus, and lowlands  Landforms are subjected to change—and some processes create new landforms while others reduce them  Process known as denudation—process of breaking down and removing loose material found at surface of the earth—gradually wears down mountains by erosion and weathering o E.g. Appalachian uplands  Weathering: the decomposition of rock and particles in situ o Broke down the solid rock of ancient mountains into smaller particles  Erosion: displacement of loose material by geomorphic processes such as wind, water, and ice by downward movement in response to gravity o Transported these smaller particles by the means of air, ice, and water to lower locations where they were deposited  Denudation and deposition: deposit of material on the earth’s surface by various processes such as ice, water and wind o Then are constantly at work and over long periods of time dramatically reshape the earth’s surface  Earth’s surface consists of 3 types of rocks o Igneous  Formed from molten rock known as magma o Sedimentary  Formed from particles derived from previously existing rock  Through weathering and erosion rocks are broken down and transported by water, wind or ice then deposited in a lake or sea—these sediments form a soft substance and harden into rocks  Hardening occurs because of the pressure exerted by the weight of additional layers of sediments and because of chemical action that cements the particles together  Since sedimentary rocks are formed in layers (called strata) it form metamorphic rocks o Metamorphic  Igneous or sedimentary rocks have been transformed into metamorphic rocks by pressure and high temperature  Produced when the earth’s crust is subjected to folding and faulting  Faulting: process that fractures the earth’s crust while folding bends and deform the earth’s crust  Faultline: geographical terms refers to a crack in the earth’s crust  A complex faultline is known as a fault zone  Broken down into at least 14 huge slabs, each moving in response to the currents of molten material just below the crust  This motion is called continental drift (movement of earth’s crust) now known as plate tectonics—it can result in the folding and faulting Physiographic Regions  Physiographic region: a large geographic area characterized by a single landform o E.g. interior plains  Three key characteristics o It extends over a large, continuous are 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:  Canadian Shield: largest region, Precambrian crystalline rock—copper, gold, nickel  The Cordillera—most spectacular and varied topography  The Interior Plains—rivers deposited sediments in shallow sea including vegetation and dinosaur remains—have sedimentary structure that contains oil and gas deposits  The Hudson Bay Lowland—most uniform relief  Arctic Lands  The Appalachian Uplands  The Great Lakes—St. Lawrence Lowlands—smallest  Cordillera, interior plains and Appalachian uplands display strong north-south orientation to the topography of NA  Structural differences have produced particular set of mineral resources in each region  One common natural force affecting the topography of all Canadian physiographic regions was the last ice advance of the Wisconsin glaciations  Began at the end Pleistocene epoch: consisted of several glacial advances where ice retreated and mild temp prevailed  The ice advance consisted of two major ice sheets, the laurentide and cordillera  Laurentide ice sheet was centered in the Hudson Bay area o As mass increased, the weight of ice sheet caused it to move  A series of alpine glaciers coalesced into the cordillera ice sheet which spread westward into the continental shelf off the pacific coast and eastward  Glaciations from laurentide and cordillera altered geography of Canada  Laurentide ice sheet pushed southward across the Canadian shield, when the ice sheet began to melt, it deposited material in situ, and meltwaters formed glacial lakes which created a flat topography of the Manitoba lowland in western Canada  Lakes were formed from glacial scouring and then filled with meltwater from receging ice sheet The Impact of Physiography of Human Activity  Friction of distance: the effect of distance on spatial interaction; as distance increases, the number of spatial interactions (phone calls, trade in goods) diminishes Geographic Location  Canada is bounded by arctic, Atlantic and Pacific oceans making it a maritime nation  Shipping routes are crucial for Canada as a trading country  Arctic ocean mostly covered in ice, except small areas of open water surrounded by sea ice called polynyas that occur in the winter  Sea ice: ice formed from ocean water (4) types o Fast ice—frozen along coasts that extends 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 10km in diameter o Ice field—a chunk of sea ice more than 10km in diameter  In late summer, fast ice disappears leaving a narrow stretch of open water making coastal shipping possible  Under these conditions, the northwest passage would become most important route between Asia and Europe  Latitude: measure of distance north and south of equator  Longitude: distance east to west of the prime meridian Climate  Climate: describes average weather conditions for a specific place or region over a long period of time  Weather: refers to the current state of the atmosphere with a focus on weather conditions that affect people in particular place  “Climate is what we get, weather is what we expect”  Canada is associated with two northern climatic types—Arctic and Subarctic  Climate is relatively stable over long period of time, plays key role in formation of soils and natural vegetation  Climate Controls o 3 dominant climatic controls affect Canada’s weather  Variations in amount of solar energy—lower latitude receives more solar energy and therefore higher temperature than higher latitude  Global circulation of air masses  Continental effect refers to the effect of distance from oceans on temperature and precipitation—as distance from ocean increases, the annual temperature range increases and annual amount of precipitation decrease  Global Circulation System o Regional climates are contr
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