Timber-Line. — Decline in Fruit Production, etc. 25 



injury to young timber, and these become more liable to occurrence 

 as the wood near the summit is destroyed. The snow then drifts 

 over and forms great overhanging masses on the leeward side, which 

 are liable to become detached and to slide down into the valleys, car- 

 rying every thing before them. 



1 06. Young seedlings when covered with the snow are sometimes 

 broken down by its weight, as it settles from melting on the under 

 side. 



107. The Timher-IAne is the upper limit of tree growth upon 

 mountains. Its height is greatest within the tropics, and it descends 

 as we go north or south, until it reaches the surface in the Arctic 

 zone.^ It also decreases as we approach the sea-coast, and it is often, 

 from local causes, higher on one side of a mountain than on the 

 other. In the Himalayas, this line is about 11,800 feet high. On 

 the Alp? it averages 6,400 feet, and in the Rocky Mountains it 

 varies from 9,000 to 12,000 feet.' 



108. lu ascending to the timber-line, no great difference in the 

 size of the timber is observed until within a few hundred feet of the 

 limit, when the trees begin to appear short and wide-spreading, and 

 at last almost flat, and leaning from the prevailing winds. Above 

 the line, no trees whatever are found, and but little vegetation of 

 any kind, the mountain rising bleak and barren to its summit, or 

 until it reaches the eternal snows. This snowline varies with the 

 seasons, and is in some years higher or lower than in others, accord- 

 ing as the prevailing conditions of the weather may have varied. 



Decline of Fruit Production mid its Cause. 



109. It is not unusual to hear old people recall the memories of 

 their youth, when peaches and other fruits grew luxuriantly and 

 ■without special care, in regions where they are now unknown, or 

 are raised only in fiiyorable seasons and with extraordinary care. 



(1) Prof. C. C. Parry, in Prof. Hayden's Report of 1872, gives the lieigh' 

 of the timber line in some twenty places, some of them being as follows: 



FEET. . FEET. 



Mount Shasta, Cal 8,000 Gilbert' Peak, Uintas 11,100 



Cascade Range, Or 7,000 Audobon's Peak, Colo 11,325 



Ward's Peak, Monta 8,784 Mt. Engelmann, Colo 11,518 



Bridger's Peak 9,002 Gray's Peak, Colo 11,643 



Near Henry's Lake, Idaho 9,36<i Pike's Peak 12,040 



Wind River Mts 10,100 Colorado generally 11,600 to 12,000 



Long's Peak, Colo 10,800 



