



 
Hi Duncan.
A cubic yard of gravel is one yard × one yard × one yard, perhaps looking like this:
If we slice it into 2 inch slices, we have 36/2 = 18 slices, each of them 2 inches thick, with a top surface that measures one yard × one yard hence with an area of one square yard.
So if we just lay them out, the total area is 18 × 1 yard^{2} = 18 yards^{2}. Hope this helps,  


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