The decaying, partially burned, piece of wood to which the field number HH39 was given was not impressive in appearance but it was a treasure, more valuable to those who found it than any buried pirate gold for which adventurers might dig. As it was examined the climatic conditions of year after year were revealed, new ring combinations were established and the chronology was carried back to 1237 A.D., the year in which this tree had begun its life. A comparison with the ring patterns of the floating chronology showed that its 551st ring checked with that for 1251 in Beam HH39. June 22, 1929, the date on which this beam was found, is a red letter day in the history of American archaeology, for from that day it became possible to date many ruins in the Southwest, not only in a comparative sense, but in terms of the Christian calendar. Actually, of course, the floating and the absolute chronology had already overlapped but the evidence had been based on such small fragments as to be unconvincing. Duplication of ring patterns may occur if only a few rings are used. It is only if a pattern covering fifty or more rings is available that one may be assured of correct dating. It was not until the discovery of Beam HH39 that final proof was available. In the years which have elapsed since 1929 much further work has been done by Dr. Douglass and his associates, who include many brilliant students whom he has trained. The tree ring chronology now stretches back to 11 A.D. Great as was the importance of being able to establish absolute dates for a people who had left no written records, this was not the only contribution made by what have been aptly called “the talkative tree-rings”.[23] The life of man, and particularly primitive man, is greatly influenced by climatic conditions and in an arid climate such as that of the Southwest the difference between drought and adequate rainfall may, quite literally, be the difference between life and death. It is naturally an inestimable boon to the archaeologist to know the conditions under which the people he is studying lived and it enables him to understand many things, such as periods marked by expansion or by the abandonment of certain areas, which would otherwise be unintelligible.