Among these relict forms in the Krummholz may be mentioned 

 V actinium pennsylvanicum an gusti folium, V. uliginosum, V. 

 Vitis-Idaa, Kalmia angustif olia, K. glauca, and Ledum latifo- 

 lium. But as the forest advances and the conditions become 

 mesophytic, these relicts gradually disappear, forced out by the 

 other forms better adapted to the new conditions of soil and 

 decreasing light supply beneath the canopy of thickly and almost 

 impenetrably woven branches of spruce and fir. 



Of the forest itself it is not the trees which first encroach upon 

 the alpine mat, but rather the lower forms which, pushing out 

 gradually advance the tension line before the forest which closely 

 follows. This advance zone is never very conspicuous, but 

 among its members Cornus canadensis, Maianthemum cana- 

 dense. Coptis tri folia, and Linncea borealis may be mentioned. 



The North Basin. Under this discussion of the Krummholz 

 it may be advantageous to introduce the conditions as they exist 

 in the North basin. This amphitheatre of over 320 acres 

 presents an appearance even more xerophytic and alpine than 

 some of the upper limits of the mountain itself. A great 

 morainic dump of granite boulders, forming kettles, completes 

 the picture of chaotic desolation. All this is in vivid con- 

 trast with the Great basin whose altitude it approximates 

 and which supports a well developed Picea-Abies meso- 

 phytic forest. The Alpine-Tundra here reaches an extreme yet 

 characteristic development, the stages of succession being prac- 

 tically identical with those of the crest and summits. Here the 

 Krummholz also reaches an excessive development, lying in 

 most places perfectly prostrate and gnarled and twisted to a high 

 degree. Pice a is noticeably predominant, Abies being conspicu- 

 ously absent. 



At the mouth of the basin, as described above, is a moraine of 

 medium size. The Alpine-Tundra mat and the prostrate 

 Krummholz cover its northwestern side. The opposite face 

 fronting southward is, on the other hand, well clothed by a 

 Picea-Abies forest. Why has this basin and its slopes this 

 extreme xerophytic condition? It will be recalled that in the 

 discussion of the origin of the place it was stated that this basin 

 with others was the seat of local valley glaciers, and a theory 



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