88 CLIMATIC CYCLES AND TREE-GROWTH 



staff dates in their rings. The average growth was nearly 50 per cent 

 larger than the Flagstaff growth and many rings were immense. 

 The specimens were measured by Mr. Cherry, using the auto-plot 

 method. They were individually standardized by him and the result- 

 ing curve from 1719 to 1919, smoothed by geometric Hann, is shown in 

 part in figure 6. It agrees exceedingly well with the Sierra Nevada 

 collection, which extends from Calaveras Grove to Mount Wilson. 

 The cycles are 8.4, 11.2 (oc. %), 13.5, 17.4, 21.7 (3), and 35 (oc. J), 

 which classify as of Coast type. 



SPRINGVILLE GROUP OF PINES (EP») 

 The visit to Springville in early August 1925, and the collection 

 of sequoia records, has already been described on page 54. The 10 

 pine borings came from elevations between 5,000 and 6,000 feet, that 

 is, from Camp Lookout to the lower edge of the sequoias, about 4 

 miles away. Most of the pines had a local south exposure toward a 

 canyon sloping toward the west. Some of these trees were on isolated 

 points, where they could get no possible water except the rain or snow 

 which fell immediately about them. Two could not be used; one was a 

 magnificent 5-foot tree whose growth was too small to allow dating 

 in the core and whose age therefore is probably very great; the other 

 had an extensive fire injury and the rings were too erratic. Mr. Austin 

 measured this group, using the long-plot method. The trees were 

 standardized individually and the curve, 1720 to 1924, smoothed by 

 graphic Hann, is shown (since 1750) in figure 6. It shows excellent 

 variations agreeing most satisfactorily with the other Sierra Nevada 

 curves between Calaveras and Mount Wilson. It is interesting to 

 recall that the sequoias from Calaveras to Springville which show uni- 

 form cross-identification, to a considerable extent cross-identify with 

 the pines nearby. The cycles classify in the Coast type as follows: 

 8.7, 11.4, 13.4 (2), 17.4 (oc. £), 23.1, 27.6 (2, oc. £), and 34 (oc. £). 



MOUNT WILSON GROUP (W) 

 This group of 22 increment-borings, of which 8 are used, was made 

 July 25, 1925, by courtesy of the Toll Roads Company and the Mount 

 Wilson Solar Observatory, who gave permission to bore the trees. 

 The top of the mountain, about 6,000 feet elevation, is a rough semi- 

 circle of ridge, convex toward the west and south, with the inner area 

 in the form of an amphitheater of gentle slope toward the central 

 drainage wash, which flows down past Strain's Camp. Sixteen trees 

 were tested in this area, of which 8 are used, all yellow pines except 

 one sugar pine and one Douglas fir, each of which gives apparently 

 the same record as the yellow pines. The 6 Douglas firs tested on the 

 road down the mountain were defective, perhaps in part injured by 

 the road building. 



♦Elster's pines. 



