ANALYSIS OF TERRESTRIAL RECORDS 



107 



Central Pueblo Chronology — Concluded 



were very gladly recognized. It should perhaps be repeated that the value 

 was realized of this continuous ring sequence 1900 years long in a dry region 

 where the trees were giving approximate rainfall records. It also seemed to 

 the writer that it more than doubled the value of the sequoia chronology 

 because it supplied a second sequence for comparison purposes. It also lays 

 a foundation for estimates of yearly rainfall values in prehistoric times. 

 It should be added that this chronology is not yet in completely final form. 

 Improvement is coming through a better understanding of the climatic 

 characters in the growth rings. It is not probable that any important 

 changes will be required. 



Mr. Schulman is quoted in the following report on cycle comparisons 

 between Arizona and California chronologies: 



"Simultaneous analysis of the two long chronologies shows some striking 

 points of agreement in the cycle patterns, in spite of the difference of some 

 600 miles in the source areas of the respective specimens. At many settings 

 the patterns show such fine resemblance in the details as to leave the strong 

 impression that the same forces causing fluctuations are operating in both 

 regions. However, emphasis on different cycles is visibly different in many 

 cases in the two regions, hence there is no perfect correspondence in the con- 

 current maxima. Agreement is seen in the entire 1900 years; there is a 

 strong suggestion that it is successively better in more recent times. 



"In the settings showing some of the best points of correspondence, given 

 below, there is usually not only agreement in the particular cycle setting, but 

 also in other cycles evidenced by slant alignments in the cyclogram. The 

 following analyses made in five overlapping intervals show cycles common to 

 the two chronologies; the cycle lengths listed are of course in years. 

 1500 to 1900: 10, 11£ (1750-1900), 13.5 (1750-1900), 17, 19 

 1100 to 1600: 10 (1100-1250), 12 (1300-1600), 15 (1100-1300), 19-20, 27 

 700 to 1200: 13£ (700-850), 16£ (950-1200), 19, 23 (700-1000) 

 450 to 900 : 7, 13 or 14, 27 

 10 to 500 : 7, 13 or 14 

 "Simultaneous analysis of the compressed curves of the two chronologies 

 (5 year means), viewing 1900 years at once, yields even better results. The 

 following cycles were found to agree well. 



