[paul.fr]

i hear that minerals will eventually become rocks, which inturn become soil. but how?

[Bass]

minerals + heat and pressure = rocks
rocks + erosion = soils

[pete_inthehills]

I like to think of this not as two seperate equations, but one big cyclical one.

rocks + erosion + organic matter = soil; soil + heat + pressure = rocks; rocks + erosion....round and round and round

pete
inthehills

[_Stefan_]

Can rock be formed by pressure without heat? Like the different layers of soil and rock you find as you dig deep deep down?

[eric l]

Can rock be formed by pressure without heat? Like the different layers of soil and rock you find as you dig deep deep down?

I remember being shown formations consisting of a kind of natural concrete. 
Wikipedia has an article on such agglomerates :  ...sorry, you cannot view external links. To see them, please REGISTER or LOGIN

[pete_inthehills]

often the pressure comes from burial and that causes heat as well, but I do remember something about pressure alone causing minerals to bond.  It was something like pressure melting or some such.  And there is the usual biological/chemical factors.  Oolites are a good example.  A grain of sand rolls around on a lime mud sea floor, gets a coating of lime mud and they eventually chemically bond to make an oolite.  So yeah, you don't need heat, but they often work together.

pete
inthehills