Peñasco Blanco is the third largest great house in Chaco Canyon, the important ancient Puebloan archaeological area.
The site is located on the south side of the canyon, three miles west of the important site of Pueblo Bonito, the largest great house of the region.
Peñasco Blanco Architecture
Peñasco Blanco has an oval plan different from the typical D-shape recognizable in other Chacoan great houses such as Pueblo Bonito, Pueblo Alto and Chetro Ketl. The site is composed by four great kivas, two in the main plaza and two outside the building.
Tree ring dating shows that construction at Peñasco Blanco began around A.D. 900, when a series of rooms was constructed near the center of the main building, forming an arc. As in other great houses, the buildings along the perimeter of the site are 2 floors tall, whereas the row of rooms facing the plaza are single story.
A third floor was added in a second construction phase, around A.D. 1000, along with additional rooms.
Archaeological Research at Peñasco Blanco
Peñasco Blanco was never extensively excavated during archaeological investigations at Chaco Canyon. However, some rooms were tested during the excavation at Pueblo Bonito by Richard Wetherill at the end of the 19th century, to verify the reported presence of huge quantities of turquoise in the site. Later on, in the 1920s Frank Roberts, a graduate student under the supervision of Neil Judd, organized the pottery types found in some trash mound at Peñasco Blanco, helping the reconstruction of the Chacoan chronological sequence.
Near Peñasco Blanco passed also one of the famous Chacoan Road, The Ahshislepah Road, connecting the great house to the Chaco and Escavada washes at the bottom of the canyon.
Peñasco Blanco Environment and Decline
Peñasco Blanco was constructed atop the mesa, on the rim of the canyon. Archaeologists believe that a salty lake existed in the canyon below the site before AD 900 and that this explained the location of Peñasco Blanco. When the water level started to decrease due to lake sedimentation and increase of rainfall which breached the dune that bounded the lake, soil erosion hindered farming activities.
This event marked also a period of decline in great house construction.
Sources
This glossary entry is a part of the About.com guide to the Guide to Anasazi, and the Dictionary of Archaeology.
Kantner, John, 2004, Ancient Puebloan Southwest, Cambridge University Press, Cambridge. UK
Vivian, R. Gwinn and Bruce Hilpert, 2002, The Chaco Handbook. An Encyclopedic Guide. The University of Utah Press, Salt Lake City.