ILLUSTRATIONS. 



PLATES. 



PAGE. 



PLATE 1. 



A. Bottomless pits near Flagstaff, illus- 



trating drainage through lime- 

 stone 12 



B. Yellow pine forest of northern Ari- 



zona 12 



PLATE 2. 



Cross-identification of rings of growth 



in yellow pine (Pinus ponderosa) . 24 

 PLATE 3. 



A. Section of Scotch pine from Southern 



England 30 



B. Section of Scotch pine from coast of 



Norway 30 



PLATE 4. 



A. Section of Scotch pine from 6s, Nor- 



way 36 



B. Section of Scotch pine from Dalarne, 



Sweden 36 



PLATE 5. 



A. Upland contours, above Camp 6 in 



Sequoia Grove: D-19 46 



B. Basin contours, Indian Basin, look- 



ing S. E. : D-12 and 13 in center. 46 

 PLATE 6. 



A. Cutting radial sample from end of 



log, Converse Hoist, D-20, age 

 2800 years 50 



B. Site of oldest tree, Converse Hoist, 



D-21, age 3200 years 50 



PLATE 7. 



A. Cutting sample from stump, Enter- 



prise: D-22, age 3000 years 52 



B. Centennial stump, Enterprise; cut in 



1874, D-23, age 3075 years 52 



PLATE 8. 



A. Section of Scotch pine from Ebers- 



walde, Prussia, showing solar 

 rhythm 74 



B. Another section from the same forest, 



showing same rhythm 74 



PLATE 9. 



A. Periodogram of the sunspot numbers, 

 1755-1911. Corrugations show 

 periods. The numbers give length 

 of period in years. The white 

 line is the year 1830 and shows 

 Phase 88 



PAQK. 

 PLATE 9 continued. 



B. Differential pattern used in making 



the periodogram, consisting of 

 the sunspot curve mounted in 

 multiple 88 



C. Same pattern photographed out of 



focus to show discontinuities in 

 the vertical lines 88 



D. Sweep of sunspot numbers, 1755-1911 88 



E. Differential pattern of sunspot num- 



bers made b5' the periodograph 

 process 88 



PLATE 10. 



A. The automatic optical periodbgraph. 94 



B. Differential patterns of Sequoia rec- 



ord, 3200 years at 11.4 94 



PLATE 11. 



A. Periodogram of standard 5-year 



period 96 



B. Periodogram of mixed periods 96 



C. Periodogram of sunspot numbers 



1610-1910 96 



D. Periodogram of Flagstaff 500-year 



record to show cycles between 



4 and 15 years of length 96 



E. Periodogram of same continued to 



25 years 96 



PLATE 12. Differential patterns: 



a. Sunspot numbers, 1610-1910 at 11.4. 108 



h. 57 European trees, 1830-1910 at 11.4. 108 



c. 80 European trees, 1800-1910 at 11.4. 108 



d. South Sweden, 1830-1910 at 12.0. . . 108 



e. Vermont group, 1650-1910, at 11.3. 108 

 /. Flagstaff group, 500 years, at 11.4 ... 108 



g. Flagstaff group at 23.5 years 108 



h. Norway, 1740-1910, at 23.8 years.. . 108 



i. Austria, 1830-1910, at 22.0 years. . . 108 



j. Norway, N-2 400 years, at 33.0 .... 108 



k. Vermont, 250 years, at 32.5 108 



/. Sweden, 1740-1910, at 37.0 108 



m. Sequoia, 1300-250 B. C., at 33.0 108 



n. Flagstaff, 500 years, at 33.0 108 



u. Sequoia, 3200 years at 101 108 



p. Flagstaff, 500 years at 120 108 



q. Standard 5-year period at 5.0 years. 108 

 r. 5 to 10 year logarithmic variable 



period at 8.0 108 



