Layers of the Earth

Geosphere

The Earth as a System

• Integrated system of rock, air, water, and living things.

• This system is divided into four parts:– atmosphere (air)– hydrosphere (water)– biosphere (living things)– geosphere (rock)

Geosphere

• Solid part of the Earth’s crust that consists of all rock, and the soils and sediments on Earth’s surface.

• Most located in Earth’s interior

Earth’s Interior

• Seismic Waves: the waves that travel through the Earth’s interior during an earthquake.

• Altered by the type of material that it travels through.

Seismologists

• Scientists who measure changes in these waves to determine that the earth’s interior is made in layers.

Composition of the Earth

• Three layers:– crust– mantle– core

• Density increases towards the center of the Earth

Crust

• Thin, outer layer.• Made up of light

elements• less than 1% of Earth’s

mass• 5-70km thick

Mantle

• Layer beneath the crust

• 64% of mass of Earth• 2,900 km thick• Made of

– lithosphere– asthenosphere– mesosphere

Lithosphere

• Outer layer• cool, rigid• divided up into

huge tectonic plates

Asthenosphere

• 250 km thick• solid, plastic layer

made of rock• flows very slowly

and allows tectonic plates to move across

Mesosphere

• 2,250 km thick• “middle” sphere• lower part of mantle

Core

• 3,248 km radius• sphere of hot, dense

nickel and iron• 4,000 - 5,000 °C• 1/3 of the Earth’s mass• Made of

– Outer Core– Inner Core

• Outer Core; 2,200 km thick, outer shell, made of liquid nickel and iron

• Inner Core: 1,228 km radius; a sphere of solid iron and nickel

First Life???

• First life may have first evolved deep in the crust and then migrated to the surface when conditions became favorable.

• “extremophiles”• Hypothesized that the biomass below the

surface far exceeds the biomass at the surface.

• Be able to draw and label the three layers of the earth (crust, mantle, and core) as well as the 5 layers based on physical properties (lithosphere, asthenosphere, mesosphere, outer and inner core).