Inside the Earth What are we walking on?

The Center Of The Earth

Earth Layers The Earth is divided into four main layers. *Inner Core *Outer Core *Mantle *Crust

The Crust *The crust makes up 1% of the Earth. * The Earth’s crust is like the skin of an apple. It is very thin compared to the other three layers. *The crust makes up 1% of the Earth. * The crust of the Earth is broken into many pieces called plates.

The Crust The crust is only about 3-5 miles (8 kilometers) thick under the oceans(oceanic crust) and about 25 miles (32 kilometers) thick under the continents (continental crust).

The Crust OUTER LAYER 5-100 km thick 2 types of crust OCEANIC (very dense, made of basalt) CONTINENTAL (less dense, made of granite)

Oceanic and Continental Crust

Granite/older Basalt/Younger

The Mantle The mantle is the layer below the crust. The mantle is the largest layer of the Earth. The mantle is divided into two regions: the upper and lower sections.

Mantle Solid but capable of flow (like hot asphalt or fudge) Upper Mantle Convection Currents Middle Mantle Lower Mantle Mantle Solid but capable of flow (like hot asphalt or fudge) Thickest layer of the Earth (making up 70% of the Earth’s mass) The hot material (magma) in the mantle rises to the top of the mantle, cools, then sinks, reheats, and rises again. These convection currents cause changes in the Earth’s surface The movement of the lithospheric plates and the convection currents will be covered more in-depth during the next essential question.

Outer Core * The core of the Earth is like a ball of very hot metals. * The outer core is liquid. * The outer core is made up of iron and is very dense.

Inner Core * The inner core of the Earth has temperatures and pressures so great that the metals are squeezed together and are not able to move. * The inner core is a solid.

Density and Pressure increase as depth increases

Earth’s Layers How are the earth’s layers similar to an egg? Shell=crust Egg white=mantle Yolk=core

Physical Structure of the Earth Lithosphere- rigid outer layer (crust) Asthenosphere- solid rock that flows slowly (like hot asphalt)

Lithosphere The lithosphere (geosphere) is the "solid" part of Earth. It has two parts, the crust and the upper mantle The lithosphere “ sits on the” asthenosphere. The Earth’s Plates are the lithosphere. It is the rocky, solid portion of the crust. Made up of mostly Silicon( Si) and Oxygen (O).

The separate plates of the lithosphere (crust and upper mantle) move very slowly in response to the “convecting” part of the mantle.

Asthenosphere This is the layer below the lithosphere. This layer is “ plastic –like”. It is somewhat solid/liquid. You can say that it is malleable. Very important in terms of plate tectonics.

Tectonic Plates Earth’s crust is broken into about 19 pieces These plates move on top of the asthenosphere

The crustal plates move along smoothly but sometimes they get stuck and pressure builds up.

The pressure builds and causes an Earthquake as rocks break and crack.                                                                                 San Francisco City Hall after the 1906 Earthquake. (from Steinbrugge Collection of the UC Berkeley Earthquake Engineering Research Center) The pressure builds and causes an Earthquake as rocks break and crack.