china clay mining in cornwall, traditional method. ds has to write a pragraph on it, and i cant understand it. Help!

[vvvodka]

please

he has a rather nice diagram, with numbers, and a wheel. but i dont understand head or tail of it. (reasonably literate, i have a degree ) but i have no idea what overburden is, how its formed, what happens to it, or anything. can anyone please help?
Ive googled, but nothing useful has come up.

ds is in year four.

overburden is the surface soil that must be moved away to get at coal seams and mineral deposits.
Thank God it's only a paragraph, I think I would fall asleep after any more than that.
en.wikipedia.org/wiki/Overburden
books.google.co.uk/books?id=P94DAAAAMBAJ&pg=PA551&lpg=PA551&dq=%2B%22china+clay%22+%2B%22Removing+th e+overburden%22&source=bl&ots=I7Fiatd3ja&sig=q7uUMGzbBGtzE6wTixPXBU-VVE&hl=en&ei=mnNoS7XpIMKRjAfCpN i1CQ&sa=X&oi=bookresult&ct=result&resnum=7&ved=0CBsQ6AEwBg#v=onepage&q=%2B%22china%20clay%22%20%2B% 22Removing%20the%20overburden%22&f=false
Good luck

www.mineralszone.com/minerals/china-clay.html

I think that's probably as much as he wants to know about it for a lifetime

thank you