January 08, 2003
The Big Bend National Park area (along the Rio Grande in southwestern Texas) is a patchwork quilt of geological formations that dates back millions of years. Some of the most striking formations along the southern regions of the park are at Cerro Castellan - Tuff Canyon. The narrow, deep canyon was carved out of consolidated volcanic ash (tuff). On the above photo, the tuff fields are strewn beside the roadway like solidified sand dunes. Tuffs can be classified as crystal tuffs, lithic tuffs, vitric tuffs (glass), or lapilli tuffs.