NO. I ARCHITECTURE OF PUEBLO BONITO — JUDD VJ 



Bonito. — Thousands of pine logs had gone into the roofing of Pueblo 

 Bonito. We wanted to learn the source of those logs ; we hoped to 

 discover when they were felled. Toward this second objective, the 

 tree-ring method developed by Dr. A. E. Douglass, then director of 

 Steward Observatory, University of Arizona, as a means of measur- 

 ing the effect of sunspots upon climate and tree growth, seemed 

 most promising for our purpose. Using materials furnished by the 

 American Museum of Natural History he had previously correlated 

 Pueblo Bonito with Aztec Ruin and learned that sections of beams 

 then in hand showed Pueblo Bonito to be older than Aztec. 



In 1922 Dr. Douglass graciously agreed to aid the Society's search, 

 and I promptly sent him all the wood samples we had recovered from 

 Pueblo Bonito the year before. But I am reasonably sure that, as he 

 studied these specimens, his thoughts were focused more upon sunspot 

 influences than upon the age of Pueblo Bonito. It was 7 years until, 

 and largely in consequence of the National Geographic Society's 

 special Beam Expeditions of 1923, 1928, and 1929, he recognized the 

 feasibility of a tree-ring calendar reaching backward into unrecorded ' 

 history (Douglass, 1929, 1935). 



At the beginning of our search for the age of Pueblo Bonito 

 Dr. Douglass, who had been working with the giant redwoods of 

 California, assured me that any timber less than 6 inches in diameter 

 was scarcely worth saving. But it was not long thereafter before he 

 was eagerly scanning every scrap we salvaged — splintered door lintels, 

 beam borings, and charcoal paraffined and wrapped with twine. I 

 mention these facts because his early results, published in the National 

 Geographic Magazine for December 1929, and in the first number 

 of this series (Douglass, 1935), made the dating of Pueblo Bonito 

 seem such a simple achievement that few, even among his own stu- 

 dents, realize the discouragements initially encountered and overcome. 

 Now his method is commonly accepted as a trustworthy guide in 

 Southwestern archeology, and many minds have lengthened his 

 original list of dated tree rings (Douglass, 1935), 



The 97 specimens from Pueblo Bonito sent to Douglass in 1922 

 and following, together with the place of origin and his determina- 

 tions, are presented hereinafter, but individually they told us more 

 than their age. They told us that many had been cut in winter or 

 late autumn ; that many had grown where moisture was surprisingly 

 constant for a region now virtually waterless. Because the individual 

 specimens were generally from straight-grained timbers, clean, 

 smooth, and unscarred by transportation it was obvious the trees they 



