CHAPTER 1 SECTION 2Changes Within the Earth

Physical Characteristics

Geology- study of the earth’s physical structure and history- looks at changes of the earth, causes and effects, predictions- all from the history of the earth (about 4.6 billion years)

Physical Characteristics(The Earth’s Layers)

page 44

The inside of the earth is made up of three separate layers- core- mantle- crust

Physical Characteristics(The Earth’s Layers)

Core- center of the earth consists of very hot metal (mainly iron/some nickel)- inner core- dense, solid- outer core- molten, liquid

Mantle (1,800 miles thick)- located around the core- thick layer of rock- mostly solid

Crust- thin, rocky surface- located below the oceans (5 miles thick)- located below continents (22 miles thick)

Physical Characteristics(Land, Air, and Water)

page 45

Physical geographers study elements of the earth’s natural environment (spheres)- and look at how they operate and interact with each other and with people- lithosphere- atmosphere- hydrosphere- biosphere

Physical Characteristics(Land, Air, and Water)

Land- continents (7)- large landmasses in the oceans

Water- 70% of the earth’s surface

Physical CharacteristicsLandforms

Land covers about 30% of the earth’s surface

Land is made up of four main kinds of Landforms – natural features of the earth’s land surface- Mountains - Plateaus- Hills - Plains

*Each landform is described by:- Elevation – height above sea level- Relief – the difference in elevation between the highest and lowest points

Landforms - Mountains

Mountains are the highest of the world’s landforms

*mountains generally have a high relief

Landforms - Hills

Hills are lower than mountains*generally, have a low relief

Landforms - Plateaus

Plateaus are raised areas of flatland (or almost flat)

*most of them have a low relief

Landforms - Plains

Plains are large areas of flat or rolling land

*they have a low relief

Physical Processes

Forces that shape landforms- Volcanoes

- forms when magma breaks through earth’s crust

- lava- molten rock located on the surface

- Movements in the Crust- fold- rock layers bend and buckle- faults- breaks in the earth’s crust

Understanding the Pastpage 46

Plate Tectonic Theory

Understanding the Pastpage 47

Continental Drift Theory- Alfred Wegener (1900s)

- German scientist- Pangaea-

supercontinent - it began

to break up into separate continents about 180 million years ago

*What evidence was believed to be found to support his theory?

Understanding the Pastpage 48-49

Plate Movement- convection

When Plates Meet- spreading- subduction- convergence- faulting

Understanding the Past

Explaining Volcanoes-Ring of Fire- a circle of volcanoes surrounding the Pacific Ocean

- “Hot Spots”- hot regions deep within the earth’s mantle- as molten rock rises towards earth’s surface, the magma may heat underground water and produce hot springs or geysers