Andes Mountains, South America

Evidence of Continental Drift

Earth’s Layers

Layers of the Earth

• There are two ways that scientists label the layers of the Earth.– Composition layers– Physical layers

Composition (What it is made of)

• Crust

• Mantle

• Core

Earth’s Layers

• How are the earth’s layers similar to an egg?

• Shell=crust• Egg white=mantle• Yolk=core

The Crust

• Outer layer• 5-100 km thick• Thinnest layer• 2 types of crust

– Oceanic (very dense, made of basalt)

– Continental (less dense, made of granite)

Oceanic and Continental Crust

The Mantle

• Middle layer• Very thick layer• Roughly 2800 km

thick• No one has ever

drilled to the mantle• It is VERY hot • composed of silicate

rocks that are rich in iron and magnesium

• Even though its solid it can flow

Convection Currents

Convection Currents Cause the Tectonic Plates to move

Movement of these plates Cause:

1.Earth Quakes2.Mountains3.Volcanoes4.Rift valleys5.Tsunamis

Tectonic Plates• Earth’s crust is broken into about 19

pieces

• These plates move on top of the asthenosphere

The Core

• Made mostly of Iron and Nickel

• 1/3 of the earth’s mass

• Very hot• The core’s diameter is

about the size of Mars (6856 km )

Physical Layers

• The less familiar layers are the physical layers.

• They are based on how the layer looks or acts.

Physical Structure of the Earth

• Lithosphere (Crust) - (15-300 km) rigid outer layer• The tectonic Plates• A combination of crust and the upper region of

the mantle• Cold and brittle (easily broken)

Physical Layers

• Asthenosphere

• weak sphere” (250 km)– Hard rock that acts

like warm tar or honey

– Ductile and highly Viscous

• involved in plate tectonic movements

Mesosphere

• Layer found between the asthenosphere and the outer core

Physical Layers Continued

• Outer Core- (2200 km)– liquid layer

• Inner Core- (diameter= 2456 km)• Solid, dense core of the planet• Densest layer of the planet

Side by side comparison

LithosphereLithosphere

AsthenosphereAsthenosphere

Outer CoreOuter Core

Inner CoreInner Core

CrustCrust

MantleMantle

CoreCore

The “spheres”

• Atmosphere– Least dense layer of the Earth– Made of mostly oxygen and nitrogen– Surrounds the Earth– Filters out harmful radiation

• Biosphere– Layer that all life is in– Not a specific location, just anywhere life is

found

Hydrosphere

– Density= ~1.0 g/mL• Describes the combined

mass of water found on, under, and over the surface of a planet.

• Approximately 75% of the Earth's surface, an area of some 361 million square kilometres (is covered by ocean.

Interesting fact…

• Did you know?...

– The center of the Earth’s core is hotter than the surface of the sun. The temperature of Earth’s inner core reaches 6000 °C whereas the surface of the sun is roughly 5500 °C.

• The sun’s core, however, is 15,000,000 °C