World Geography

Structure of the Earth

I. Inside the Earth

A. Core- solid metallic center of the earth, made up of iron & nickel

B. Mantle- lying on the core, a soft layer of molten rock

1. Magma (molten rock) is created when the mantle melts the underside of the crust

2. crust- thin layer of rock at the earth's surface

II. On and above the earth

A. atmosphere- layer of gases surrounding the earth

1. contains oxygen, protects the earth, provides weather and climate

B. lithosphere- solid rock portion of the earth's surface

1. some is below water, forms the floor of the ocean

2. continents- huge land masses above water

C. hydrosphere- the water elements on earth

1. oceans, seas, rivers, lakes, water in the atmosphere

D. biosphere- the atmosphere, lithosphere and hydrosphere together, which is where plants and animals live

E. continental drift- Alfred Wegner- the earth was once a super-continent (Pangea)

1. as the super-continent split, the continents drifted

III. Forces that Shape the Earth

A. Plate Tectonics

1. tectonic plates- enormous moving pieces that form the earth's crust

2. 3 forms of plate movements

a. divergent boundary- plates move apart or spread

b. convergent boundary- plates collide, causing one plate to either dive under or ride up over the other plate

c. transform boundary- plates slide past one another

B. Earthquakes

1. violent movement of the earth that occurs when the plates grind or slip past one another

a. results in the squeezing, stretching, and shearing motions of the earth's crust- causes damage

2. can sometimes cause tsunamis- giant wave in the ocean

C. Volcanoes

1. a crack in the earth's surface where magma, gases, and water pour out of the crust

a. magma that flows slowly then cools is called lava

b. volcanoes do not erupt on a schedule and can be inactive for long periods of time before erupting

4.Ring of Fire- a zone around the rim of the Pacific, location of the vast majority of active volcanoes

a. along plate boundaries

b. Hot Spot- volcano where the crust is very thin and magma melts through- Hawaiian Islands

D. Weathering

1.physical and chemical processes that change characteristices of rock on the earth's surface

a. occurs over many years, creates sediment

2. mechanical weathering- changes the size of the rock

3. chemical weathering- changes the rock into a new substance

E. Erosion

1. when weathered material is moved by the wind, water, ice or gravity- a transporting agent must be present

F. Building Soil

1. process of forming soil caused by weathering and erosion

a. soil is a loose mixture of weathered rock, organic matter, air and water

b. detemine the types of vegetation that can grow in a location