Grey Stone (Moria) Base
Paint the sand with watered down Abbadon Black.
(This just gives a nicer base to work with than raw sand.)
Heavy dry brush the base with Rhinox Hide
(This gives the base a rich undertone.)
Medium dry brush with Gorthor Brown.
(This gives a bit more colour, and an extra layer of undertone.)
Light/medium dry brush with Dawnstone.
(The aim here is to pick up the larger grains of sand/small rocks.)
Light dry brush with a mix of Whitescar and Dawnstone.
(This is to give the rocks a highlight.)
Paint the sides of the base with Dawnstone.
(Much nicer than the black and fits in perfectly with any game board done with similar colours.)