Earth Structure

Four Main Layers

• Inner core• Outer core• Mantle• Crust

Crust

• Thinnest Layer• Two types of crust :

Oceanic: made mostly igneous rock and Basalt. Found under ocean, thin

Continental: made mostly of granite. Found under continents, thick

Mantle

• Located above the outer core • Below the crust is where the mantle starts• Largest Layer• 80% of Earth’s volume & 68% of Earth’s mass• Composed of iron• Density, Temperature, And pressure increases the

deeper you go into the mantle• Lithosphere :upper, solid part of mantle• Asthenosphere: under lithosphere, solid rock flows very

slowly

Outer Core

• Surrounds inner core• Temp. : 2200c-5000c• Iron and Nickel, Liquid

Inner Core

• Solid, iron and nickel• Temp. can reach to 5000c• Solid, because of the pressure put on the

core• Solid core is the source of Earth’s

magnetic field

Continental Drift

Alfred Wegener

• First proposed the theory of continental Drift• Continental Drift was his theory that continents were

joined together then drifted apart• Named Pangaea a supercontinent• Theory was rejected because he couldn’t explain which

force pushes or pull continentsFound pieces of evidence: Geologic Climate Fossil1940s: Technology was developed

Climate

evidence in the changing climates during the past.

Geologic

• evidence in layers of rocks across continents.

FossilEvidence of fossils are found

in certain places

Fossil

Fossil

• Remains or physical evidence of an organism preserved by geological processes

• Preserved in sedimentary rock• Sediment slows down decay• Bones and shells are resistant to decay,

more commonly preserved tissue

Examples

• Fossils in rock• Fossils in Amber• Petrification• Fossils in asphalt• Frozen fossil• Trace Fossil• Mold• Cast• Index Fossil

Amber

• Harden tree sap

Bugs, lizard, and frogs

Petrified Fossil

• A process in which minerals replace organism tissue

Types:• Space in bone/wood fills up with mineral• Organisms are replaced

by minerals

Frozen

• Cold temperatures slow down decay• Many frozen fossil are preserved from last

ice age

Fossil in asphalt

• Wells up in sticky, thick pools• Traps and preserves fossil in asphalt

Trace Fossil

• Naturally preserved evidence of animal activity

• Footprints fill with sediment

Shows how big their

Footprint was.

Molds And Cast

• Mold: a cavity in a rock where a plant and animal was buried.

• Cast: an object created when sediment fills mold and becomes a rock.

Index Fossil

• Fossils of organisms that lived during a relatively short, well-defined geologic time span.

Geologic Time

Geologic scale

• Divisions

Largest division is epoch

Second largest division- periods

Third largest division- eras

Eras

• Three eras:• Cenozoic: means “New Life”• Mesozoic: means “middle animals”• Paleozoic: means "ancient life"

Cenozoic

Mesozoic

Paleozoic