90 CLIMATIC CYCLES AND TREE-GROWTH 



ferent gears in the measuring instrument. However, each tree-record 

 was subsequently standardized in the usual way and the resulting 

 curve, 1402 to 1923, was smoothed by graphic Hann. The part since 

 1750 is shown in figure 6. This curve is strongly of the Flagstaff type 

 in the last century or so, except that 1818 to 1821 have large growth 

 instead of small. The cycles are 7.3, 11.4, 14.4 (oc. £), 17.8 (3), 21.3, 

 25.9, 29.0, and 34. This is a Coast type. 



PINE VALLEY GROUP (PV) 



The Pine Valley here referred to is in the mountains some 50 miles 

 east of San Diego, California, at an elevation of over 5,000 feet. 

 The trees are more numerous at the southern end of the 2-mile valley, 

 and of five increment-cores, three come from the vicinity of the 

 summer resort there; one which could not be dated comes from the 

 northern end and one comes from a very large tree about midway. 

 Four were secured in the summer of 1923 and the undated one in 

 August 1925. The rings cross-identify readily with those at Flagstaff. 

 Mr. Hawkins measured the rings, using the auto-plot method. Stand- 

 ardizing was effected by reducing mathematically each tree-record to a 

 set of departures from its own mean. The resulting curve, 1736 to 

 1923, smoothed as usual, is given in part in figure 6. This curve 

 matches the Charleston group with great exactness and therefore is 

 closely like the Flagstaff-type curve. The cycles are 6.6, 10.1, 14.4, 

 18.4, 25.2 (oc. ^ or -J-), 32 (2, oc. £), and 35, which rather resemble 

 the Arizona cycles. 



MISCELLANEOUS GROUPS 



The groups mentioned below have been collected for various pur- 

 poses, but for one reason or another do not lend themselves to the 

 study of cycle distribution. They are added here because reference 

 has been or will be made to them. 



SEQUOIAS 



Calaveras group (CVS) — This group consists of two increments- 

 cores, three v-cuts on fallen trees collected in 1924, and a tracing 

 (recently measured and plotted by Mr. Austin) made by Mr. Manson 

 in the 1880 's. This was copied from an original tracing, which, with 

 a separate copy, was filed in the library of the University of Cali- 

 fornia. A copy was loaned to me by the Department of Agriculture 

 of the University of California, and another was sent me by Professor 

 C. F. Marvin, chief of the United States Weather Bureau. This 

 "longitudinal" record is probably from the Dance Hall tree; it goes 

 back to 621 a. d. The specimen which I collected from the "Old 

 Maid" goes back to 525 a. d. My record from the "Father of the 

 Forest" begins at 922 a. d. 



