Centennial Museum gecko logo

Desert Diary

Archaeology/Pictograph Ages


This page was designed with CSS, and looks best in a CSS-aware browser--which, unfortunately, yours is not. However, the document should still be readable, though not presented in the most sophisticated manner.

Pictographs drawn with pigments on rock surfaces are known to archaeologists as rock art. Such drawings are common throughout the Chihuahuan Desert and may last for thousands of years. Problems are twofold, though—meanings and ages.

Addressing the question of age, some of the more recent art can be dated based on historic knowledge of Native American and European styles. However, it's only been in relatively recent years that we have been able to bring technology to bear on older images. With improvements in radiocarbon dating technology, we now need only minute amounts of carbon for dating. This requires that the carbon is derived from organisms or from minerals in balance with atmospheric radiocarbon at the time of their formation. In the first case, charcoal used for black is ideal, though other organic matter can bind pigments. In the second case, ideally, the minerals should be both beneath and over the drawing, bracketing the time of creation. Technical problems are common, but finally we can begin to put such art into chronological order.

pen and ink

Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.



Rowe, M. W., and K. L. Steelman. 2003. Dating rock art. Mammoth Trumpet, 18(2):4-7, 14-15.