These hills are a massif, somewhat triangular, of sandstone on top of a granite base. Erosion has carved the hills into terraces, with high plains dropping to steep gorges. The region has regular rainfall during the summer, with rivers flowing a few times a year. The rock art was produced over a long period of time and evolved considerably, having no less than fifteen distinct styles. These styles differ in the depictions of animals and humans, dress, weapons, and in the color scheme.
Some styles outline the subject matter, while others fill the image with dots or checks.
Other colors were, in decreasing order of use, white , black , and violet. Brown was used only in certain periods. Yellow, made from yellow ochre , appears rarely. The most common combination was red and white. These pigments were ground to a fine powder and mixed with fat, and were then applied to the rock walls.