Paleo Slide Set: Tree Rings: Ancient Chronicles of Environmental Change
Keet Seel Ruins, Navajo National Monument, Arizona

The father of dendrochronology is widely acknowledged to be A.E. Douglass, 
who came to Arizona at the turn of the 20th century as an astronomer interested 
in sunspots and climate. A pioneer in the study of the relationships between 
tree growth, climate, and solar cycles, he was also instrumental in developing 
dendrochronology as a method to date archaeological remains. By matching the 
ring patterns in wood from roof beams and around door and window openings 
with the patterns in a dated tree-ring chronology derived from living trees, 
he and others were able to date many of the Anasazi ruins in the southwestern 
United States. The Anasazi ruin Keet Seel was built around AD 1250. The Anasazi 
are believed to be the ancestors of the modern Pueblo Indians of northern Arizona 
and New Mexico. They inhabited parts of Colorado, Utah, Arizona, and New Mexico 
from about AD 900-1300. During this time, they built many cliff dwellings 
and multi-storied towns in the canyon country of the southwestern U.S., 
of which Keet Seel is one example.

Photo Credits:
Peter Brown
Rocky Mountain Tree-Ring Research, Ft. Collins, CO