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Published byAbel Freeman Modified over 9 years ago
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GEOGRAPHY
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Study of the earth as the home of people(Yi-Fu Tuan, 1991) Study of variations in phenomena from place to place(Holt- Jensen, 1980) Definitions
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Physical Geography-study of physical features of the earth Human Geography-studies the man-made features of the earth Passive or static human geography-deals with the action of nature upon man Active or dynamic human geography-deals with reaction or action of man upon nature Types of Geography
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Factors influence, determine and condition the distribution and activities of man Physical features Climate Vegetation Animal life
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Evidences 1.Edge of shadow of the earth on the moon during eclipse. 2.Possibility of cirum-navigation. 3.The horizon appearing as a clear marked circle. Size and shape of the earth
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Physical features of earth
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Oblate spheroid or ellipsoid shape Polar radius-3950 miles, equatorial radius-3963 miles Diameter-7926 miles-equator, 7900 mile-poles Polar cirucumference-24,818 miles Equatorial circumference-24,860miles Physical features of earth
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Rotation Revolution Movements of Earth
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Formation of day and night Formation of sunset and sunrise Getting sense of time Moving body experiences coriolis force Caused bulge at equator flattened at poles Siderial day-earth takes 23 h, 56min, 4.09 sec for one rotation Effects of earth’s rotation
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Unequal length of the day and night Formation of seasons Tropical year-earth takes 365d, 5h, 48min and 45 sec for one revolution around the sun Effects of earth’s revolution
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Inner core-radius-1070km, solid, very dense, magnetized, rich in iron and nickel, 5000°C Outer core-4000°C, liquid –iron & nickel Mantle-2835km thick, 1500-3000°C, magnesium-iron silicates Crust-rigid, cold, thin-SIAL, SIMA STRUCTURE OF THE EARTH
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Moho –boundary between the crust and the mantle Lithosphere-rigid layer of the crust and upper mantle Asthenosphere - sub region of the mantle extending about 250km below the lithosphere
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Continental crustOceanic crust Average thickness-35kmAverage thickness-11km including overlying water Main rock type-graniteMain rock type-gabbro Density -2.8g/cm³Density-3.0g/cm³ Differences between continental crust and oceanic crust
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