Typically a poly chrome cave painting was created in three basic stages, which might vary significantly according to the experience and cultural maturity of the artist, the nature and contours of the rock surface, the strength and type of light, and the raw materials available. Take a picture of a bison, for instance. First, the outline and basic features of the animal are drawn on the cave wall, either by scoring the surface of the rock with a sharpened stone, or by applying a black outline using charcoal or manganese. Second, the completed drawing<span> of the animal would be colored or filled in with red ocher or other pigments. Third, the edges of the animal's body would be shaded with black or another pigment to increase its three- dimensional. Alternatively, depending on whether or not the contour of the cave wall made it necessary, additional engraving or even sculpting would be applied to boost volume and relief.</span>
