to initialf lu-sv waiortourses aiui even river systems Even if 

 they did not actually produce such comparatively major topo- 

 graphical changes, they completely altered the vegetative cover 

 of enormous areas simply by raising or lowering the level of the 

 water table 



If you will climb the mountains and look down upon almost 

 any of the valleys leading northwest from the central massif of 

 Maine on a clear day. you will notice that they descend by a 

 series of gigantic steps, clearly defined by a difference in color 

 between the hardwoods that grow on the steps themselves and 

 the darker softwoods that grow on the surrounding slopes. A 

 great deal of this pattern is the work of beaver and has been 

 accomplished in a few thousand years. These animals, as we 

 have already described in more detail, require both standing and 

 running water, and the closer to the Arctic the more precise are 

 their requirements. By damming a stream here and cutting a 

 sluice or canal there, they tend to make the water flowing from 

 the heights proceed in a series of jerks. But once they have 

 brought part of it to a halt at any point, the water pushes out 

 into the surrounding soil and even into the rocks — for even 

 granite has a considerable free-water content— and thus raises 

 the water table even on steep slopes. Some trees and bushes 

 cannot grow with their tap roots in water; others not only can 

 but need to do so. Thus, when beaver make a dam. a large area 

 surrounding the resultant lake is apt to change its botanical face. 

 And it can do so in a surprisingly short time. 1 have carried on 

 a minor and haphazard experiment of this nature in northern 

 New Jersey by building two dams across a bottom pasture of 

 black earth underlaid by clay. In five years I have, instead of a 

 pasture, a twenty-foot forest of small trees and large shrubs, and 



Overleaf lell-luinJ ptige: Dogwood m the sprinf; in a typical 

 temperate broad-leafed woodland of Appalachta Right-hand 

 page: The glory of early autumn in the same province 



some acres of swamp. What is more, the dominant trees all 

 around the periphery of both have changed— those that predomi- 

 nated before having become sickly or even died, and others 

 having sprouted phenomenally. 



The speed at which vegetation can change is often, in fact. 

 grossly underestimated, and although crops are divided into four 

 classes — algae which you can harvest daily: leafy crops, once a 

 month; cereals and tubers, once a year; and trees, once every 

 half-century — all may proliferate at a multiple rate if the amount 

 of daylight, the temperature, or the water availability is in- 

 creased. There is an experiment, now in its tenth year, on the 

 eastern seaboard wherein a square mile of sandy soil previously 

 supporting only scrub pine and some holly has had its annual 

 rainfall artificially raised by means of sprinklers from 43 to 143 

 inches. It now supports a dense forest well over fifty feet tall, 

 containing all manner of animal life from worms and snails to 

 birds that were never seen in the area before, and some of them 

 not previously outside the subtropical belt. Water alone can 

 perform miracles. 



SUBURBAN ANIMALS 



It is in Appaladiia perhaps more than anywhere else that we 

 see the direct evidences of the last ice advance or crustal slip. 



Beaver can fell almost any tree and lay it in any desired spot, despite the tree's inclination or the 

 slope of the land. They then cut it into logs which they roll to water. 



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