chapter 1 section 2. geography – the study of the earth’s physical structure and history...
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Changes Within the EarthChapter 1Section 2
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
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
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
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
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
Understanding the PastPlate Tectonics – theory states the earth’s
outer shell is not one solid sheet of rock
Continental DriftContinent
al drift theory – Pangaea One large
continent that broke apart
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
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
Expanding VolcanoesRing of Fire – circle of volcanoes surrounding
the Pacific Ocean
Changes on the Earth’s Surface
Chapter 1Section 3
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
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
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
Glaciers- huge, slow-moving sheets of ice
Moraines – ridge like piles of rocks and debris
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