school help: i am doing an exam in school on science of the universe, it is my end of school exam and i am doing some research does anyone know: - Help.com

Look under Thermal Expansion and Freeze-Thaw Weathering: http://en.wikipedia.org/wiki/Weatheri…

freezing and cooling of rocks is a big subject.
You can imagine if a large mass of rock expands then even
a small expansion with enough rock can produce very large forces.
In the millions of pounds per square inch.
This is enough to crush rocks.
When you crush up rocks you get little rocks.
Crush up enough little rocks and you get sand.
Wear down the sand and you get mud or clay.
If you pile up the little pieces of rock and mud and sand until
it’s a very deep then the weight becomes once again very high
and the pressure is very high.
If this material goes far enough into the earth temperature heats up
in this material can be recycled by melting it into new rock.
This will go on indefinitely.
Only God knows when it will end.
It’s been going on for about 6 billion years.