 The most commonly harvested tree species was ponderosa pine; the Chacoans felled approximately 16,000 of them for use at Chetro Ketl, and the species is now absent from the canyon.Archeologists Florence M. Hawley and Neil Judd proposed that a plentiful forest may have existed in and around the canyon during the 10th and 11th centuries, but was eventually destroyed by over-harvesting.Dean and Warren believe this is unlikely, but the presence of trees in the canyon during the 20th century "suggests that some pines may have been locally available for use in the large towns".