INTKODUCTION 



15 



(X 



1870 



1880 



1890 



1900 



1910 



1920 



data 



Fig. 3 — a. Cross-identity at 70 miles, Fort Defiance and Black Mesa groups. 



b. Winter rainfall with 2\ yr. lag in smoothed values, and tree growth. 



150 



100 



50 



1890 



1900 1910 1920 



Fig. 4 — Tree growth and river run-off. 



1930 



