(reference photo)
reference photo a
Finally, halftones are added to the cliffs on the left and the foreground foliage. Halftones are inbetween the light and shadow values. By bridging the light and shadow values, they help to round out the forms. A few small dark accents are also added to complete the painting.

If you haven't already looked at Tutorial 1, the same technique is used there to paint a still life.