Changes Within the Earth

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