E ARTH ’ S L AYERS Notes

E ARTH ’ S L AYERS The Earth can be divided into different layers based on either composition or based on their different physical properties. Density and temperature both increase for deeper layers of the Earth.

E ARTH ’ S C OMPOSITIONAL L AYERS Composition: what something is made of

T HE C RUST The crust is the outermost, thinnest, least dense layer. Continental crust is made mostly of the rock granite and is thicker and less dense than oceanic crust. Oceanic crust is made mostly of the rock basalt. Overall, crustal rocks are rich in the elements silicon (Si) and oxygen (O).

M ANTLE The mantle is the hot, middle, thickest layer and accounts for most of the Earth's bulk. It is denser than the crust, but not as dense as the core. The density of the mantle increases with depth due to increasing pressure. Mantle rocks are richer in iron (Fe) and magnesium (Mg) than crustal rocks. Diamonds form in the high pressure conditions of the mantle.

T HE C ORE The core lies at Earth's center. The core is made mostly of iron and nickel, and it is the hottest, densest layer.

E ARTH ’ S P HYSICAL L AYERS

L ITHOSPHERE The lithosphere is the cold, brittle layer at Earth's surface. It is a solid layer that contains all of the crust and a very thin part of the mantle's top. Overall, the lithosphere is a stiff, rigid layer that is broken into large pieces called tectonic plates. These plates move around on top of the less rigid layer below them.

O UTER C ORE The outer core is the liquid, outer portion of the Earth's core. The slow, gradual flow in the outer core produces the Earth's magnetic field.

I NNER C ORE The inner core is the solid, inner portion of the Earth's core.

E ARTH ’ S F ORMATION

H OW DID E ARTH F ORM ? About 4.6 billion years ago. Materials from a large cloud of gas and dust formed together. This was because of GRAVITY!

G RAVITY ? Gravity: The force that every object exerts on all other objects because of its mass. The closer the objects, the more gravity. The bigger (or more mass) the more gravity. Those dust and gas particles… well, they began to gravitate, and create planets. The larger the objects, the more pull.

E ARTH ’ S L AYERS FORMED Because of DENSITY! The more dense something is, the more it will sink. All of the materials that made up the Earth in it’s early years were “sorted” by their densities. Most dense (Heaviest) to the bottom. That is why the core is iron!!!

M AGNETOSPHERE

E ARTH ’ S M AGNETIC F IELD The inner core spins faster than the outer core This produces streams of flowing, molten iron in the outer core. This creates magnetism from the iron flowing. Over time, the magnetism can change!

M AGNETOSPHERE – W HAT IS THAT ? Protects us from cosmic rays and charged particles from the sun.

T HE E ND