The North American continent has a wealth of sites containing cave art, although they are unevenly distributed. The largest concentration, in number as well as in variety and richness, can be found in the west and southwest. Paintings predominate in certain areas, while others feature engravings. Sometimes, equal proportions of both techniques can be found. A predominance of naturalistic or representative motifs (stylized to some degree) can also be observed, above all in the east and northeast and in certain restricted areas of the southwest, including Baja California. However, in most of the west and southwest the trend is toward the abstract.