EFFECTS OF BURNING FOREST. 363 
zes the rocks and stones upon and near the surface; * it con- 
sumes a portion of the half-decayed vegetable mould which 
served to hold its mineral particles together and to retain the 
water of precipitation, and thus loosens, pulverizes, and dries 
the earth; it destroys reptiles, insects, and worms, with their 
egos, and the seeds of trees and of smaller plants; it supplies, 
in the ashes which it deposits on the surface, important ele- 
ments for the growth of a new forest clothing, as well as of the 
usual objects of agricultural industry ; and by the changes thus 
produced, it fits the ground for the reception of a vegetation 
different in character from that which had spontaneously cov- 
ered it. These new conditions help to explain the natural 
succession of forest crops, so generally observed in all woods 
cleared by fire and then abandoned. There is no doubt, how- 
ever, that other influences contribute to the same result, be- 
cause effects more or less analogous follow when the trees are 
destroyed by other causes, as by high winds, by the woodman’s 
axe, and even by natural decay.t 
* Tn the burning over of a hill-forest in the Lower Engadine, in September, 
1865, the fire was so intense as to shatter and calcine the rocks on the slope, 
and their fragments were precipitated into the valley below.—Mivista Fo- 
restale del Regno @ Lialia, Ottobre, 1865, p. 474. 
{ The remarkable mounds and other earthworks constructed in the valley 
of the Ohio and elsewhere in the territory of the United States, by a people 
apparently more advanced in culture than the modern Indian, were overgrown 
with a dense clothing of forest when first discovered by the whites. But 
though the ground where they were erected must have been occupied by a 
large population for a considerable length of time, and therefore entirely 
cleared, the trees which grew upon the ancient fortresses and the adjacent 
lands were not distinguishable in species, or even in dimensions and character 
of growth, from the neighboring forests, where the soil seemed never to have 
been disturbed. This apparent exception to the law of change of crop in 
natural forest growth was ingeniously explained by General Harrison’s sugges- 
tion, that the lapse of time since the era of the mound-builders was so great 
as to have embraced several successive generations of trees, and occasioned, 
by their rotation, a return to the original vegetation. 
The successive changes in the spontaneous growth of the forest, as proved 
by the character of the wood found in bogs, are such as to have suggested the 
theory of a considerable change of climate during the human period. But 
