82 CLIMATIC CYCLES AND TREE-GROWTH 



southwest of Russia, New Mexico. Mr. C. W. Cherry measured 

 these specimens by auto-plot method. They were approximately 

 standardized by assigning added weight to the slower-growing trees 

 in forming the averages. The resulting curve from 1736 to 1920, 

 smoothed by a careful geometric Harm and mostly shown in figure 5, 

 presents strong variations which have much in common with the 

 Pike's Peak curves. The cycles are 11.2 (oc. £), 13-4, 15.3 (2), 17.8, 

 22.1 (i or i), 27.5 (i), and 36 (i). 



SANTA FE GROUP (SF) 



This group was collected on September 5, 1922, with the aid of Mr. 

 B. Z. McCullough, who took me some 4 or 5 miles up the canyon 

 east of Santa Fe, New Mexico. The trees selected had usually a 

 north exposure and were in the general vicinity of the ranger station. 

 They were chosen at considerable height above the brook, so as not 

 to be influenced by it. All of the six cores were readily dated by 

 resemblance to the Flagstaff series. Mr. C. W. Cherry measured 

 these rings by the auto-plot method. After standardizing, he plotted 

 their average in a curve from 1749 to 1921 and smoothed it by a careful 

 geometric Hann. The result given in figure 5 shows excellent varia- 

 tions with distinct apparent similarity to curves of the Flagstaff area, 

 but the cycles conform more to the Rocky Mountain zone, being 

 10.2, 11.9, 18.4 (2), 22.4, 27.5, and 35 (2, oc. $). The absence of a 

 14-year period places it with the Rocky Mountain groups, although 

 the absence of the 17-year period is unusual in that zone. 



BASIN MOUNTAIN UPPER GROUP (BMH) 



The collection of this and the two following groups is due to the 

 cooperation of the archaeologists. In August 1919 I visited the Aztec 

 ruins, New Mexico; thence Mr. Morris took me to Sullivan's saw- 

 mill on Basin Mountain, in Colorado, nearly 40 miles north of Aztec 

 and perhaps 15 southwest of Durango. The mountain has a per- 

 fectly flat top about a mile across, covered with pines. The saw-mill 

 is 2 or 3 miles away, in the basin to the east. The pine trees extend 

 down to the mill and a few scattered ones are found even lower 

 down. Two v-cuts were taken from logs at the mill; five more were 

 cut from stumps on the mountain-top before it got dark, and on the 

 way down we cut the three which made the lower group, of which 

 the last was cut by the light of matches long after nightfall. This 

 division into upper and lower groups was made on account of varying 

 water-supply in the soil. The date was August 13, 1919. Mr. J. F. 

 Freeman measured all these specimens by the standard cathetometer 

 method and the seven from the mountain- top have been combined 

 without standardizing to form a curve beginning 1588 and ending 

 1919, which cross-identifies minutely with the Flagstaff tree-growth. 



