There are two types of crust : 1.Continental crust forms the land which is mainly made of granite, which is a low density ignious rock. The continental crust is 30-35 km thick. 2.Under the oceans is the oceanic crust - usually 6-8 km thick. Its quite dense and made up of an igneous rock called basalt.
The asthenosphere is the top layer of the mantle.
The lithosphere is the uppermost layer of the Earth.
the Earths lithosphere is split into 15 large techtonic plates and over 20 small ones.
The plates move slowly on the assthenosphere.
Plate boundaries are where the 'action' is. Most earthquakes and volcanos are found on plate boundaries.
constructive plate boundaries - fromed when two plates move apart.
Destructive plate boundaries - formed when two plates collide.
Conservation plate boundaries- formed when two plates slide past each other.
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