170 
The cause of the more rapid weathering of south slopes (i. e., those fae- 
ing the south) is, no doubt, partially due to expansion and contraction. The 
massive rocks of the Niagara, Clinton and Madison beds of the Ordovician 
have been more rapidly broken to pieces on the south slopes than on the 
north, because of the much greater daily change of temperature on the 
south than on the north slopes. This is especially true during the winter 
season. 
The chief agent, however, in producing the variations in the sections 
noted, is that of frost. The action of frost in producing such variation is 
three fold. First, the almost daily thawing and freezing of the moisture 
in the rocks of the south slopes during the winter produces a more rapid 
disintegration of these rocks, than would take place on the north slopes, 
where thawing occurs but few times comparatively during the winter 
season. 
Again the surface soil of the slopes facing the south goes through the 
freezing and thawing process several scores of times during the winter, 
while that of the north slopes remains frozen almost continuously during 
the average wintry season. The “creeping of soils,” resulting from frost 
action, is too well known to need explanation here, and must, to a large 
degree, account for the variations noted. 
Again, the soil of the north slopes is frequently frozen, and even coy- 
ered with snow or ice, while that of the south slopes is unfrozen. Hence, 
the erosive action of many winter rains is almost nothing on the north 
slopes, while it may be quite marked on the south slopes. This is an addi- 
tional cause for the variation noted in the sections taken. 
With the exception of the north slope of Crowe Ravine and the east 
slope of Clifty, the region considered is all wooded, while the unwooded 
slopes have been so but for a few years. What the effect of weathering 
and erosive agencies may be upon north and south slopes of land from 
which the forest trees have long been removed, has not been investigated, 
but from the greater abundance of loose stones on the south slopes of 
cleared and more or less neglected land, it is probable that the variation 
in the effects of weathering and erosion on the north and south slopes is 
even more striking than in the case of land covered with forest growth. 
