I would toss in some fake stones in strata layers, each with different sets of stones because it all still looks like hard dirt only. Keep the stones more flat though as if embedded will into the hard dirt. The stones could be a very similar close color the the per strata layer. More color variations per each strata layer, some in very similar color shades while others could be more apart yet keeping the colors close in hue. Some strata could be more or less displaced in variation.