Earth's Natural Phenomenon

Earth's Natural Phenomenon

Layers of the Earth

Layers of the Earth

• The Earth is composed of four different layers.

• Many geologists believe that as the Earth cooled, the heavier, denser materials sank to the center and the lighter materials rose to the top.

• Because of this, the crust is made of the lightest materials (rock- basalts and granites) and the core consists of heavy metals (nickel and iron).

Multiple Choice

Where would you find the layer of earth with the lightest materials?

• The center

• The surface

• The middle

Multiple Choice

Let's be more specific. In which layer would you find the lightest materials?

• The crust

• The mantle

• The inner core

• The outer core

Layers of the Earth

The crust is the layer that you live on, and it is the most widely studied and understood. The mantle is much hotter and has the ability to flow. The Outer and Inner Cores are hotter still with pressures so great that you would be squeezed into a ball smaller than a marble if you were able to go to the center of the Earth!!!!!!

Multiple Choice

What would most likely happen to you if you travelled to the center of the earth?

• Nothing

• You would freeze to death

• You would be squeezed into the size of a marble

• You would double in size

The Crust

Earth's Crust is like the skin of an apple. It is very thin compared to the other three layers. The crust is about 3-5 miles thick under the oceans and about 25 miles thick under the continents. The temperatures of the crust vary from air temperature on top to about 1600*F (870*C) in the deepest parts. You can bake chocolate lava cake in your oven at 350 degrees Fahrenheit, at 1600 degrees F. rocks begin to melt into magma.

The Crust Continued

• The crust is about 3-5 miles deep under the ocean - this is called oceanic crust

• The crust is about 25 miles deep on land - the is called continental crust.

Tectonic Plates

• The crust of the Earth is broken into many pieces called plates.

• The plates "float" on the soft, plastic mantle which is located below the crust.

• These plates usually move along smoothly but sometimes they stick and build up pressure.

• The pressure builds and the rock bends until it snaps. When this occurs an Earthquake is the result!

Multiple Choice

What happens when the pressure builds up along tectonic plates?

• An earthquake

• A thunderstorm

• A hurricane

• A volcanic eruption

The Crust and Tectonic Plates

• Notice how thin the crust of the Earth is in comparison to the other layers.

• The seven continents and ocean plates basically float across the mantle which is composed of much hotter and denser materials

Crust Composition

The crust is composed of two basic rock types granite and basalt. The continental crust is composed mostly of granite. The oceanic crust consists of a volcanic lava rock called basalt.

Multiple Choice

What is the crust mostly made of?

• Granite and obsidian

• Granite and basalt

• Basalt and obsidian

• Pumice and Marble

Lithosphere

• Basaltic rocks of the ocean plates are much denser and heavier than the granitic rock of the continental plates. Because of this the continents ride on the denser oceanic plates. The crust and the upper layer of the mantle together make up a zone of rigid, brittle rock called the Lithosphere.

Multiple Choice

What are the combined crust and mantle known as?

• hydrosphere

• atmosphere

• lithosphere

• asthenosphere

Asthenosphere

The layer below the rigid lithosphere is a zone of asphalt-like consistency called the Asthenosphere. The asthenosphere is the part of the mantle that flows and moves the plates of the Earth.

Multiple Choice

The __________________ is the part of the mantle that flows and moves the plates of the Earth.

• hydrosphere

• atmosphere

• lithosphere

• asthenosphere

The Mantle

The mantle is the layer located below the crust. It is the largest layer of the Earth, 1800 miles thick. The mantle is composed of very hot, dense rock. This layer of rock even flows like asphalt under a heavy weight. This flow is due to great temperature differences from the bottom to the top of the mantle. The movement of the mantle moves the earth! The temperature of the mantle varies from 1600*F at the top to about 4000* F near the bottom!

Multiple Choice

What causes the flow (convection currents) from the bottom to the top of the mantle.

• Extreme temperature differences

• The appearance and disappearance of rainbows

• Little leprechauns stirring up earth's gold

Multiple Choice

Which layer of the Earth is the largest?

• Crust

• Mantle

• Outer Core

• Inner Core

The Mantle

The mantle is made of much denser, thicker material, because of this the plates "float" on it like oil floats on water.

Many geologists believe that the mantle "flows" because of convection currents. 

Multiple Choice

What causes tectonic plates to float?

• Their light weight

• Their oily consistency

• The type of rock they are made of.

• Convection currents

Convection Currents

 Convection currents are caused by the very hot material at the deepest part of the mantle rising, then cooling, sinking again and then heating, rising and repeating the cycle over and over. If you were to boil a pot of water and place wooden blocks on the surface, you could watch the convection currents move in the liquid.

Convection Currents

When the convection currents flow in the mantle they also move the crust. The crust gets a free ride with these currents. A conveyor belt in a factory moves boxes like the convection currents in the mantle moves the plates of the Earth.

Multiple Choice

Convection Currents are caused when...

• Hot material rises and cool material sinks

• Cool material rises and hot material sinks

The Outer Core

The core of the Earth is like a ball of very hot metals. (4000 degrees F. to 9000 degrees F.) The outer core is so hot that the metals in it are all in the liquid state. The outer core is located about 1800 milesbeneath the crust and is about 1400 miles thick. The outer core is composed of the melted metals nickel and iron. This layer makes the earth like a giant magnet.

 

Multiple Choice

Which layer causes the earth's magnetism?

• Crust

• Mantle

• Outer Core

• Inner Core

The 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 about like a liquid, but are forced to vibrate in place as a solid. The inner core begins about 4000 miles beneath the crust and is about 800 miles thick. The temperatures may reach 9000 dgrees F. and the pressures are 45,000,000 pounds per square inch. This is 3,000,000 times the air pressure on you!

Multiple Choice

What causes the earth's inner core to be a solid?

• Temperature

• Pressure

• Convection Currents

Start Exploring Plate Tectonics

https://www.amnh.org/explore/ology/earth/plates-on-the-move2