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Page 1: Changes Within the Earth

Changes Within the EarthChapter 1Section 2

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GEOGRAPHY – the study of the earth’s physical structure and history

Physical CharacteristicsThe Earth’s Layers

Core – center (inner/outer) Mantle – mostly solid Crust – rocky surface layer

Natural forces interact with the earth’s crust, creating landforms, or natural features, found on the earths surface

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Land, Air, and WaterGeographers often talk of the different

elements of the earth’s natural environment as a set of related “spheres” dominated by different physical forms Lithosphere – layer of soil, land, rock, landforms Atmosphere – layer of air, water, and other

substances above the surface Hydrosphere – consists of water, oceans, lakes and

rivers Biosphere – the world of plants, animals, and other

living things that occupy the land and water

70% water Continents – large landmasses in the oceans

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Landforms are commonly classified according to differences in relief – the difference in elevations between the highest and lowest pointsMajor landforms – mountains, hills, plateaus,

and plains

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Physical Processes – “What forces shaped the landforms here?”1st – internal forces that originated in the

earth’s interior Volcanism

•Form when magma breaks through the earth’s crust

•On the surface, molten rock is called lava

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Movement in the CrustBending and buckling breaks the earth’s crust

Results in a foldHardness of rock and strength of movement

determines whether a fault or fold

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Understanding the PastPlate Tectonics – theory states the earth’s

outer shell is not one solid sheet of rock

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Continental DriftContinent

al drift theory – Pangaea One large

continent that broke apart

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Seafloor SpreadingUsing sonar, scientists began to map the floor

of the Atlantic Ocean, discovering that it was not flat

Youngest rock was found nearest underwater ridge system

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Plate Movement/MeetingConvection - a circular movement caused when

a material is heated, expands and rises, then cools and falls

Subduction – when a denser plate slides beneath the other, an arc of volcanic islands may form along the plate boundary

When two oceanic plates collide, neither slides Buckling, bending, folding

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Expanding VolcanoesRing of Fire – circle of volcanoes surrounding

the Pacific Ocean

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Changes on the Earth’s Surface

Chapter 1Section 3

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Weathering- the breakdown of rock at or near the earth’s

surface into smaller pieces

Physical/Mechanical Weathering – when rock is actually broken or weakened physicallyFreezing waterFrost wedgingSeeds taking root in cracks of rock

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Chemical Weathering – altering a rock’s chemical makeup by changing the minerals that form the rock or combining them with new chemical elementsWater and carbon dioxideMoistureAcid Rain – chemicals in polluted air combine

with water vapor and fall back to earth

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Erosion- movement of weathered material such as

gravel, soil, and sandWater – largest canyons and deepest valleys

created by moving water Sediment – small particles of soil, sand, and gravel

Wind – 2nd major cause Loess – windblown deposits of mineral-rich dust and

silt Sandstorms

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Glaciers- huge, slow-moving sheets of ice

Moraines – ridge like piles of rocks and debris