INTRODUCTION 



11 



In connection with cross-dating, figure 2 has been arranged to show simi- 

 larity in measured values over a small area by comparing the growth records 

 of five pine trees collected within an acre near Prescott, Arizona, in 1911. 

 The mean mutual correlation coefficient of each to the other four is 0.85 ± 

 0.02. Better agreement is noticed in the rings of deficient years than in the 

 wider rings. Figure 3a shows the agreement between curves obtained from 

 two groups 70 miles apart; one consists of seven pine trees near Fort Defiance 

 (LCFD) ; the other has three Douglas firs (group name PNN) from a location 

 called Pinyon in the south central part of Black Mesa. 



;ott 



90 1800 10 20 30 40 1850 60 70 80 90 1900 10 



Fig. 2 — Cross-identity (similarity of growth in each year) in Prescott trees. 



The examples of cross-dating over this area are so tremendously numerous 

 and the similarities so striking that these ring resemblances over the Pueblo 

 Area assume the proportions of a phenomenon which has been overlooked 

 because of the stronger human interest in the dating of prehistoric ruins that 

 became possible through its agency. Up to the present time only a few 

 miscellaneous examples of cross-identification have been published out of 

 many thousands. It is hoped that a large display of it will be made in a forth- 

 coming volume. 



RING TYPES AND TOPOGRAPHY 



The importance of cross-identification described above was first thoroughly 

 realized in 1911 after comparing ring records in trees near Prescott, Arizona. 

 An excellent group from near town, whose location I visited at the time, gave 



