RE+-+Why+is+the+earth's+crust+unstable

__**The structure of the earth**__

Inside the earth it's hot - really hot. We know that becasue of the molten lava that spews from volcanoes. Also, in some places, you get hot springs and geysers. The earth isn't a solid bal of rock. It's made up of different layers like an apple. The skin/peel is the crust, the white fleshy part the mantle and where the seeds are the core.

The earth's crust is divided into large pieces, called plates. It's unstable because these plates move very slowly. The different plates meets at plate margins, or boundaries. There are four main types of plate margins:


 * Constructive - where the plates are moving apart
 * Conservative - where the plates slide past each other
 * Collision - where the plates push against each other often forming mountains - Himalayas
 * Destructive - where the plates collide

Excellent Animations - []

__**Structure of the earth**__



__**Why do the plates move?**__

__**Types of crust**__

The Earth's crust is made up of:
 * Oceanic crust - is found under the ocean
 * Continental crust - is found underneath the continents or land masses

continental crust meet || Doesn't sink ||
 * **Oceanic Crust** || **Continental Crust** ||
 * 5-10km thick || 25-100kn thick ||
 * Dense || Less dense ||
 * Sinks into the mantle when oceanic and
 * The oldest is only 180 million years old || Very old - 3-4 billion years old ||
 * Forms constantly at constructive plate margins || New crust isn't formed ||
 * Destroyed at destructive plate margins || Cannot be destroyed ||