FORESTRY IN FRANCE. 257 
of the mountain-sides is produced with a constantly increasing 
intensity. The rain-water, no longer interrupted in its fall, retained 
by the spongy vegetable mould, nor hindered in its downward flow 
by the thousands of obstacles which a living covering would oppose 
to its progress, flows off the surface of the ground with extra- 
ordinary rapidity, and, carrying with it large quantities of loose 
soil, suddenly fills up the torrent beds. These latter, scoured out 
by the rush of water, charged with mud, stones, and rocks, cut their 
way deeper and deeper into the mountains; and their banks, deprived 
of support at the base, fall inwards, the débris being borne onwards 
to the level ground below. The cracks and slips occasioned in this 
manner extend to a great distance on either side of the torrent, 
especially on the side on which the strata slope towards it, and the 
effect is much increased when the upper layer of rock is loose, and 
lies upon an impermeable bed ; the water then saturates the loose 
rock, and, penetrating through it, and through the cracks and fis- 
sures, flows over the hard surface, the superincumbent mass being 
precipitated, either suddenly or by slow degrees, into the valley 
below. The same effect is produced in the whole net-work of 
watercourses, both principal and tributary, which traverse the 
mountain-sides ; the upper strata, over enormous areas, with fields, 
houses, and even entire villages, being carried down into the 
valleys, and the whole region, which presents little to the eye but 
a series of unstable slopes of black marl, has an indescribably deso- 
late appearance. It may be added that when the hill-sides are 
covered with trees, the snow, which has accumulated during the 
winter months, disappears gradually under the influence of the milder 
temperature which accompanies the advancing spring; but when 
the trees have been removed, and the masses of snow are conse- 
quently exposed to the full force of the sun’s rays, they melt rapidly, 
and produce results on the mountain-sides similar to those which 
follow the occurrence of heavy storms of rain. 
But the damage does not stop here, for on reaching the compara- 
tively level valleys which form the main lines of drainage of the 
mountain range, the stones, gravel, and sand, transported by the 
numerous torrents are deposited. These valleys being usually 
very fertile, are occupied by fields, villages, and towns, which are 
connected by roads and sometimes by railways, constructed with 
many bridges, retaining walls, and other masonry-works ; and as, 
by degrees, enormous areas become covered with débris—some- 
times this result is produced suddenly and without warning—the 
