hmmm
I like it as it is - however, if You would allow me to propose a possible improvement:
You use two kinds of rock structure
the edgy one, which could be sandstone, and the rounded one, that looks pretty similar to eroded granite. Now You could give the rounded boulders a slight touch of reddish/brownish, intensifying from top to bottom in order to simulate water runoff. then this would allude to different types of stone.
I am saying this only because Your work always looks very precise and authentic and You appear to go to the limits
