33^ PHYSICAL GEOGRAPHY. 



of one, two, or three feet high and trees available for the market. The 

 limit of the trees is not wholly dependent upon the elevation of the slope, 

 but is partly influenced by the ravines, and, to a much greater extent, by 

 the exposure of the mountain side, which causes a variation of from one 

 to two hundred feet in altitude. Upon Mt. Madison and the north-western 

 slope of Mt. Washington, the forest line, according to the measurements 

 of Prof. Guyot, reaches the height of 4150 feet above the sea, and, upon 

 the face of Mt. Clinton, which has a westerly exposure, it attains an eleva- 

 tion of 4250 feet; while, again, at the ledge (the most northerly extremity 

 of the sub-alpine region on Mt. Washington), its limit is reached at about 

 3900 feet. The alpine region occupies the summits of only the three 

 highest mountains, being limited to from one to two hundred feet of the 

 cones of Mts. Adams and Jefferson, and some seven or eight hundred 

 feet of Mt. Washington. 



On Plate C I have attempted to show by the red color the general area 

 of the alpine, and by the blue the limits of the sub-alpine region. Stand- 

 ing upon the summit of Mt. Washington, the main peak, and looking at 

 the mountains which lie to the north, it will be seen that, while the sub- 

 alpine region follows the main chain, it extends, also, a short distance 

 along the ridge running eastwardly from the peak of Mt. Madison, and 

 to a much greater distance north-eastwardly from Mt. Washington, in the 

 general direction of the carriage-road, terminating, at a lower level than 

 usual, at the ledge, around which the road abruptly turns just before it 

 enters the forest. South of Mt. Washington there are two ridges: the 

 more prominent and longer range, whose peaks bear the names of Amer- 

 ican statesmen, trends toward the south-west ; the other continues in the 

 direction of the main chain lying to the north of Mt. Washington, and its 

 northernmost peaks have received the names of Davis's and Boott's spurs. 

 A slight abutment to Mt. Washington divides the angle between these 

 two, but is nearer the latter. By the union of these ridges, at their 

 junction with Mt. Washington, there is formed a broad plateau, called 

 Bigelow's lawn, sloping gradually away to the south, where the sub-alpine 

 region finds its widest boundaries, and whose southern limits I have not 

 traced as carefully as upon the opposite side of Mt. Washington, but which 

 must have, approximately, the extent shown upon the map. Within this 

 sub-alpine region, which includes also the heads of all the deeper ravines, 



