The Cliff Base Trail provides the most diverse collection of petroglyphs in Boca Negra Canyon. It is the longest of the three trails in this canyon and takes visitors back in time to view petroglyphs ranging thousands of years in age from the ancient Indians to more recent Mexican and Spanish settlers.

Boca Negra Canyon is part of the 17-mile long 'escarpment' that makes up Petroglyph National Monument. The 'escarpment' is a long, precipitous, clifflike ridge of land or rock, commonly formed by faulting or fracturing of the earth's crust.

Serpent-like petroglyphs are common images due to the snakes which have inhabited the area for centuries

Only the artist knows the true significance of these petroglyphs giving visitors the chance to create their own meaning from abstract symbols like this one

Masks or symbolic faces are thought to have been used in ceremonies by the Ancestral Pueblo

Some believe this type of petroglyph to represent an important figure wearing a head-dress

Circles and Spirals are very common petroglyphs among all ancient Indian tribes - but their meaning is not known