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