130 B. HE. Fernow—The Battle of the Forest. 
tions, which continually wrested the reconquered ground from 
the persistent advance guards of the arboreal army, annihilating 
them again and again. : 
Finally, when the more settled geologic and climatic condi- 
tions of the present era arrived and the sun arose over a world 
ready for human habitation, man found what we are pleased to 
call the virgin forest—a product of long continued evolutionary 
changes—occupying most, 1f not all the dry land, and ever intent 
upon extending its realm. 
This prehistoric review of the battle of the forest cannot be 
left without giving some historic evidences of its truth. 
Not only have paleobotanists unearthed the remnants of the 
circumpolar flora, which give evidence that it resembled that of 
present tropic and semi-tropic composition, but they have also 
shown that sequoias, magnolias, liquidambars and hickories ex- 
isted in Europe and on our own continent in regions where they 
are now extinct. We have also evidences of the repeated suc- 
cesses and reverses of the forest in its attempts to establish itself 
through long geologic transformations. 
One of the most interesting evidences of these vicissitudes in 
the battle of the forest is represented in a section of Amethyst 
mountain in Yellowstone National Park, exhibiting the remains 
of fifteen forest-growths, one above the other, buried in the lava. 
Again and again the forest subdued the inhospitable excoria- 
tions; again and again it had to yield to superior force. 
Among these petrified witnesses of former forest glory, mag- 
nolia, oak, tulip tree, sassafras, inden and ash have been iden- 
tified, accompanying the sequoia in regions where now only the 
hardiest conifer growths of pines and spruces find a congenial 
climate. 
As the forest formed and spread thus during the course of 
ages, so does it form and spread: today, unless man, driven by 
the increasing needs of existence, checks its progress and reduces 
its area by the cultivation of the soil. This natural extension 
of the forest cover or afforestation takes place readily wherever 
soil and climate is favorable, but it is accomplished just as 
surely, though infinitely slower, in unfavorable situations. On 
the naked rock, the coarse detritus and gravel beds, on the purely 
siliceous sand deposits of river and ocean, or in the hot dry 
plains, the preliminary pioneer work of the lower vegetation is 
required. Algze, lichens, mosses, grasses, herbs and shrubs must 
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