Forces of ChangeForces of Change

Why is the Earth not Flat?Why is the Earth not Flat?

Savage EarthSavage Earth• What caused this?

Savage EarthSavage Earth• What is this?

Savage EarthSavage Earth• What caused this?

Savage EarthSavage Earth• What caused this?

Let’s ReviewLet’s Review• What is physical geography?

The study of understanding the processes and patterns of the natural environment.

In other words……how the earth works!!

Earth SystemsEarth Systems• Atmosphere – air

and gasses

• Lithosphere – Earth’s surface and interior

• Biosphere – living things

• Hydrosphere – water (all forms)

Earth’s InteriorEarth’s Interior

• Inner Core – Very hot very dense.

• Outer Core – Hot molten liquid.

• Mantle – Mix of liquid and solid.

• Crust – Thin solid top layer.

Plate TectonicsPlate Tectonics• Has the Earth always looked the same?

• Observe an animation of the breakup of Pangaea.

Continental DriftContinental Drift• The theory that the earth’s crust is divided into

“plates” that slowly drift apart over time

What “fits” together?

Plate TectonicsPlate TectonicsThe study of plate movement and its consequences.

There are 3 types of plate movement

-Subduction

-Spreading

-Transformation

SubductionSubduction• A geologic process in

which one edge of one crustal plate is forced below the edge of another.

SpreadingSpreading• The process by which plates are moving

apart and new crust is created by magma pushing up from the mantle

TransformationTransformation• The process by which plates slide

horizontally past one another.

Changing the face of natureChanging the face of nature

• Are these “constructive” forces the only ones at work on the Earth?

• Imagine the world if only these forces existed…

Destructive ForcesDestructive Forces

• There are 3 types of “destructive” forces:

- Erosion

- Weathering

- Deposition

ErosionErosion• the process by

which the surface of the earth is worn away by the action of water, wind, waves, glaciers

WeatheringWeathering• the various mechanical

and chemical processes that cause exposed rock to decompose.

Mechanical Weathering caused by windblown particles

Chemical Weathering caused by acid rain

DepositionDeposition• The process of accumulating or laying

down of matter by a natural process.

Alluvial fan after a flash floodMississippi river delta