TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 85 



of 40 years. The cycles are 6.4, 11.6 (3, oc. £), 17.2 (oc. £ or J), 23.0 



(oc. \ or -J-), and 36. This strong emphasis on the single sunspot 



cycle, especially in the higher latitudes, is very characteristic of the 



Coast cycles. 



BAKER, OREGON. GROUP (BO) 



The higher parts of the pass between Baker, Oregon, and the 

 Columbia River are pine-covered, and at distances from Baker vary- 

 ing between 60 and 90 miles 8 increment-cores were obtained. 

 These are complacent, and the dating, though probably right, has 

 not the certainty of the Arizona and Rocky Mountain pines. One 

 core had to be omitted because it was erratic, probably from injury. 

 There was some cross-identification with the Boise and the Klamath 

 Falls groups. The rings were measured by Mr. Austin, using the long- 

 plot method. The records were standardized and a curve produced 

 extending from 1660 to 1924. This was smoothed by the usual graphic 

 Hann and is shown in part in figure 6. It is a trifle less complacent 

 than the Boise group and, like it, tends to show a long period of the 

 order of 40 years. The cycles are 6.8, 9.1, 11.3 (2, oc. £), 15.0, 21.8 

 (2, oc. %), and 28.4 (oc. -J). These have some of the Rocky Mountain 

 characteristics. 



DALLES GROUP (DL) 



The most beautiful part of the Columbia River Highway passes 

 through the mountain range between Portland and The Dalles. On 

 the west side of this range the rainfall is heavy and the vegetation 

 profuse; the east side of the mountains is dry, looking out onto the 

 arid areas of central Oregon. A narrow belt of yellow pine runs north 

 and south along this eastern slope. This small group of three incre- 

 ment-cores came, therefore, from a point 8 miles west of the rapids in 

 the river which gave the name, several hundred feet above the river 

 on its very steep south side. The dating between these three trees 

 was very satisfactory. The rings were measured by Mr. Austin, and 

 the standardized curve from 1765 to 1924 was smoothed in the usual 

 way and is shown in figure 6. This curve has a trace of similarity 

 to those at Baker and Boise, especially in respect to the apparent long 

 period and its phases, but its real conformity is with the California 

 curves to the south. This group shows a profound depression from 

 1890 to 1894, which suggests fire or injury of some sort. The cycles 

 are 7.2 (2), 12.6, 14.2 (3, oc. -*-), 16.4 (2), 18.3, 22.5, and 35. 



OREGON COAST GROUP (OC) 



This is the group of Douglas fir described in Volume I, which 

 came from the low coast hills 25 miles northwest of Portland, where 

 the rainfall is large and the snows of winter very rare. No real like- 

 ness in rings or in smoothed curve (graphic Hann) has been found here 

 to the groups farther inland. The smoothed curve is shown in figure 6. 



