Plate Tectonics

David Rosero - 8th period

The Three Layers

The 1st layer is the core, then mantle, then crust. The core is important because it is the middle of the Earth and it keeps everything together. The mantle makes up 84% of the Earth's volume and 67% of its mass so it does add to the Gravity of the Planet. The crust is important because it is where we live and where all the animals and where water is.

Continental Drift

Continental drift was a theory by Alfred Wegener, it is that continents are all on tectonic plates and convection currents under the plates cause the plates to move around. The 2 pieces of evidence that Alfred used was that fossils from the same plants and animals were found on 2 different continents, another is that Africa and South America fit next to each like a puzzle piece.

Plate Movement and Theory of Plate tectonics

Convection helps plates move, beacause the currents in the magma help the plates move. The Theory of Plate Tectonics is that the earth is broken into shifting plates.

Sea-Floor Spreading

Sea-Floor spreading is the formation of new areas of oceanic crust, which happens when magma comes up at mid-ocean ridges, Henry Hess discovered this. Sea-floor spreading helps explain continental drift in the theory of plate tectonics.

Plate Boundaries

There are 4 different plate boundaries, transform, divergent, convergent, and convergent with subduction. Transform plates grind against each other. Divergent plates split apart or go away from each other. Convergent plates collide. Convergent with subduction is when two plates collide and the weaker plate goes under the heavier plate

Ring of Fire

This is a huge area in the Pacific ocean full of volcanoes and accounts for about 80% of the worlds seismic activity.

Impacts of Plate Boundaries

On Transform plates, when they grind against each other they begin to cause earthquakes. On Divergent plates, when they begin to split apart they cause volcanoes, and rift valleys and if it occurs in the ocean it creates mid-ocean ridges. Convergent plates, when they begin to collide create mountains. Lastly Convergent with subduction when occurs create trenches, volcanoes, and mountains