Plate Motion Unit

-Convergent Boundary

-Divergent Boundary

-Transform Boundary

-Convection

-Pangea

-Sea-Floor Spreading

-Plate Tectonics

-Tectonic Plates

​What connections can you make from these words or their parts?

• Alfred Wegner - Continental Drift

• Common Fossil Species

• Mountain Ranges and Climactic Conditions

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In 1915, a German scientist named Alfred Wegener (VAY-guh-ner) proposed the theory of continental drift. According to this theory, the landmasses once were joined into a supercontinent called Pangaea. The landmasses then slowly drifted to their current positions.

-Wegner's ideas initially dismissed.

-Mapping of sea floor lead to the discovery of mid-ocean ridges.

-This brought validity to the theory of plate tectonics.

-Revealed the youngest rock is closest to the ridge and the oldest was farther away.

​-Scientists discover magnetic patterns on sea floor match equidistant on the ridge from both sides.

-This proposed the idea of sea-floor spreading.

-As the sea floor moves moves, so do the continents on the same piece of crust.

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• Old ocean floor moves edges of continents

• Trenches push ocean floor back to mantle

• RECYCLED!

• SUBDUCTION: crust pushing down into the mantle

• The lithosphere is made from the crust and the uppermost part of the mantle

• The lithosphere is rigid, brittle rock

• These plates float on the asthenosphere

• Heat from within the mantle rises, cools as it reaches the top, and falls back down.

• This concept, Convection, slowly moves the plates on top to move.

In the theory of plate tectonics, the earth's crust is broken into plates that move around relative to each other. As a result of this movement, three types of plate boundaries are formed: divergent, convergent, and transform boundaries.

Divergent boundaries are boundaries where plates pull away from each other, forming mild earthquakes and volcanoes as magma comes to the surface.

Convergent boundaries are boundaries where two plates are pushing into each other. They are formed when two plates collide, either crumpling up and forming mountains or pushing one of the plates under the other and back into the mantle to melt.

The third type is transform boundaries, or boundaries where plates slide past each other, forming strong earthquakes. All of this crashing, banging, and erupting are one reason why the surface of the earth has such a variety of landforms and features.

force created by rising mantle of ocean ridges that creates potential for plates to move away from the ridge

force created by sinking of a plate, or slab, that pulls on the rest of the plate