Layers Of The Earth and Plate Tectonics

Transform Boundary

A transform boundary is one where the two plates slide against each other in a sideways motion. These can be seen at fault lines and over cause earthquakes.

Pangea

200 million years ago all continents were joined as one supercontinent called Pangea. These continents slowly drifted away from each other to form the seven continents we know today.

Divergent Boundary

A divergent boundary is an area where two plates are separating. Most of these tectonic plate boundaries are located on the floor of the oceans. The separating plates form rift valleys on the ocean floor and causes sea-floor spreading

Mid-Ocean Ridge

A mid-ocean ridge is an underwater mountain system. A mid-ocean ridge marks the boundary between two plates which are moving apart. A mid ocean ridge is made by a divergent boundary.

Rift Valley

A rift valley forms when a two plates are pulling apart allowing and the land drops down between them. These valleys form when oceanic plates are moving apart at a divergent boundary.

Continental Drift Theory

Continental drift theory is the idea that the constant movement of the continents across the earth's surface caused one supercontinent called Pangea to break into the seven continents we know today. The movement is caused by by 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 and rising again. This causes the plates to move.

Convergent Boundary

Converge is a word that scientists use to describe two objects that come together. In the case of plate tectonics, the two objects coming together are large plate-like pieces of the Earth's crust. As these two plates push against each other at a convergent boundary, one is ultimately forced down beneath the other.

Plate Boundaries

Plate boundaries are where two plates meet each other. There are three types of plate boundaries: CONVERGENT --> <-- Plates move towards each other DIVERGENT <-- --> Plates move away from each other TRANSFORM --> Plates move past each other <--

Subduction Zone

Subduction zones are convergent boundaries where a continental crust converges with an oceanic crust. The heavier oceanic crust bends and begins moving downward toward the upper mantle.

Earth's Crust

The Earth's crust is the outermost and thinnest layer of the earth. It is made of solid rock and soil.

Asthenosphere

The asthenosphere is a layer of solid rock that has so much pressure and heat the rocks can flow like a liquid. The rocks are less dense than the rocks in the lithosphere. This allows the tectonic plates in the lithosphere to move around on the Earth's surface by "floating" on the rocks that are slowly flowing like a liquid.

Earth's Core

The core is split into the inner and outer core. The core is made of iron (Fe) and nickel (Ni). The inner core is solid due to the amount of pressure it is under.

Lithosphere

The lithosphere is the solid and rigid outer layer of our planet. It includes the crust and part of the upper mantle that contains rigid rocks. Beneath this layer is the asthenosphere where the rocks in this part of the upper mantle are not rigid. The rocks can flow like a liquid or break apart similar to silly putty.

Mantle

The mantle is the thickest layer of the earth. It takes up the most volume and mass of all Earth's layers.

Plate Tectonics

The plates that make up Earth's crust are all different shapes and sizes. The theory, or idea, of plate tectonics says that Earth's outer layer is made up of large, moving pieces called plates. All of Earth's land and water sit on these plates. The plates are made of solid rock.