Plate tectonics And Continental drift Pangea Plate tectonics And Continental drift

Layers of the earth crust The crust is made of light elements eg. Silicon which is sand It floats on top It is solid It is made of several different plates or pieces These are called tectonic plates.

Mantle The mantle is made of heavier minerals. It is liquefied because of pressure and heat. The heat from the core causes a convection current.

Convection currents and the link to density Density= Mass/Volume Increase the volume you decrease the density. Heating fluids makes them expand. This means the volume gets bigger and it becomes less dense. fluids that are less dense float. fluids that are more dense sink.

Convection currents make the tectonic plates move The core heats the liquid mantle. The lower mantel gets less dense and rises This pushes the crust The top of the mantle cools and becomes more dense and sink This pulls the crust

Pre lab Wood chips Crust Water Mantle and coffee with convection current Hot plate Core

Evidences of continental drift The edges of the continents fit together like a jig saw puzzle.

Evidence of continental drifts Mountain ranges and special rocks are formed in one place when the continents were together Now we see the same rocks or mountain ranges on the opposite sides of the ocean.

Evidences of continental drift Fossils of the same animal are found in South America and Africa They used to live in the same area then the continents moved apart

Evidences of continental drift Glaciers are made in arctic cold regions Glacial scratches on the rocks in Africa Therefore Africa used to be in a cold place Coal is made in tropical swamps Arctic regions have coal Therefore the Arctic used to be in a warm place

How plates move When plates spread apart this is called divergence When they push together its called convergence When they slip past each other its called transformation

DIVERGENCE The Atlantic ocean is spreading 2 cm per year Causes rift valley’s and underwater volcanoes.

Convergence When plates collide there is mountain building

Subduction When two crusts collide and one goes under the other It causes trenches and volcanoes

Slip faults or transformations This shifting of crusts is happening in California on the San Andreas fault . It causes earthquakes

Read text book Pages 317-325 Answer the Memory check questions P325