Where does soil come from?

[Mr Slappy]

I've been watching the Time Team for ages now and can't help wondering where all the soil comes from. It only seems to take a couple of hundred years before everything's covered two feet deep in soil. Where does it come from?

[spacechimp]

Dead skin. I'm not entirely sure, leaves? Could be to do with farming.

[andyjevs]

Yeah...basically it's broken down dead plant and animal material that's built up over many thousands of years.

But i'm sure logman will be along in a minute to contradict everything i've said as usual

[Clanad]

Discussed here;

http://www.theanswerbank.co.uk/Science/Question107665.html

[spacechimp]

Oh yeah, in South America there are birds and bats which do lots of droppings called guano. That stuff can build up really quickly.

[Clanad]

... and here:

http://www.theanswerbank.co.uk/Science/Question167313.html

[logman]

Its always amazed me too, mr slappy, how it can build up so much in just acouple of hundred years. Theres an archiological site not far from me, which dates back to the 15 hudreds and whats left of the building has about a metre of clay soil on top of it.

I put it down largely to the physical actions of man, ploughing, leveling and filling in but also the elements and weathering contributing in a smaller way and of course geological conditions must be considered too.

Conversely if you look at the paterns in the desert in Nasca Peru, (Which is extreamly hot and dry) these man made images of animals ect have survived and remained intact for hundreds of years, and all they are made of is a thin dark layer of sand, scraped away to reveal a lighter layer underneath, facinating stuff!..

[AB Editor]

Hi Andyjevs and others, please refrain from personal comments about other users - unless they are nice, of course. If we can just stick to answering questions without the belittling comments that would be great.

Cheerio