TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 89 



The trees which could be used were in the triangle between the 

 hotel, the Observatory museum, and Strain's Camp. One of the very 

 best, No. 14, is a large tree in the fork of the gulch just above Strain's 

 Camp, close to the upper hall. The ring record of this tree shows 

 strong Flagstaff characteristics. This group was measured by Mr. 

 Erickson, using the long-plot method. The records were standardized 

 and a curve, 1725 to 1924, smoothed by graphic Hann, is mostly 

 shown in figure 6. This curve has strong variations agreeing excel- 

 lently with the Sierra Nevada curves. The cycles are 7.7, 10.4 (2), 

 11.2 (oc. i), 15.2 (oc. $), 17.1, 22.5 (2, oc. £ or £), 29.4, and 34 (2, oc. 

 •J- or J-). These conform to the Coast type. 



SAN BERNARDINO GROUP (SB) 



The Forest Service in Los Angeles was kind enough to send me in 

 1922 some 13 increment-cores from the San Bernardino Mountains. 

 Mr. Patterson measured the rings, using the auto-plot method. Five 

 were omitted because they were too short; 2 were reserved because 

 they did not agree well with the others, which formed a real group, and 

 because there was a slight doubt of the dating before 1850; of these 

 one shows an unusually regular 17-year cycle. The remaining 6 were 

 combined into the present group. They were standardized and the 

 curve, 1819 to 1921, smoothed by graphic Hann, is shown in figure 6. 

 The very remarkable 23-year period is the most obvious thing in it. 

 In fact, a search for older trees in that region might give some very 

 interesting and valuable material. This periodic feature stands out 

 because certain maxima which show well in the Sierra Nevadas to 

 the north are here largely suppressed. The maxima which make this 

 curve interesting are all present in the Sierra Nevada curves. The 

 cycles here are 7.7, 9.8 (2), and 22.9 (4), the only case of assigning a 

 weight of 4 to any cycle. These belong to the Coast zone. 



CHARLESTON MOUNTAIN GROUP (CH) 



The collection of this group of seven cores and one 500-year v-cut 

 on July 18, 1924, has already been described on page 61. Saw Mill 

 Canyon starts just north of the main peak and cuts to the east. The 

 site of these trees is about 7,500 feet elevation and has something like 

 24 inches of rain. The canyon is narrow and composed largely of 

 gravel terraces. Three trees high up on the very steep terrace bank 

 to the south showed such slow growth that much of their records could 

 not be dated, but the other specimens from the flat canyon bottom 

 gave a fine agreement. The wash was dry. The 500-year stump was 

 close to its north edge. The rings readily cross-identify both with 

 Flagstaff trees and also with Sierra Nevada trees, thus corresponding 

 to the intermediate geographical location. Mr. Hawkins measured 

 them by the long-plot method, effecting partial standardizing by dif- 



