"Marcus Fox" wrote in message ...
I am trying to calculate a formula to determine approximately how much
earth/material I would need to create a "pile" - for want of a better word -
of a given height I could use just earth, but I could also have a pile of
rocks covered by earth.

The pile will be approximately cone shaped, and I know the formula to
calculate the volume of a cone. 1/3 pi r2 (base radius) x height. However,
since the soil will spread out and the base gets wider as the height
increases, I need to know to what degree this will happen, for example what
is the smallest slope in degrees where the pile will remain stable? 45? If
this is the case then the radius of the base will be the same as the height.

Thanks for any input.

Marcus

This is a how long is a piece of string question. In your mind
compare the 'fluidity' of fine grained sand, to that of good ol'
London clay.

I have seen the spoil form workmens trenches with 80 degree sides ie
only 10 degrees off the vertical. I have also tried to make sand
castles in the dunes and noticed that 45 degrees is about the limit.

The answer probably lies somewhere between the two. In truth you will
only find out by testing the proposition yourself to see what results
you get.

Maybe you could tell us more about the purpose of said pile, and we
might be able to deliver more practical advice.