A FOREST TOUR AMONG THE DUNES OF GASCONY. 313 
rence, and cause much loss of life and property. At a short 
distance above Barreges our attention was called to a large mass 
of snow, which, during the month of April last, fell into the 
valley, and completely blocked it up. On the opposite side 
works are in progress with a view to clothe the hill-sides above 
the cultivation and villages, and thus to reduce the danger from 
avalanches. 
We were now in a communal beech forest, which has a thin 
crop of old trees, with very good naturally-sown young growth on 
the ground; but there were many windfalls. We entered a 
nursery where young beech trees are raised for filling up places 
where the young crop is incomplete; and we then descended to 
inspect the large weir (barrage), which forms part of a system of 
works constructed in order to reduce the slope of the torrent bed. 
On one side of the main valley the strata are exceptionally 
loose, and the water, cutting its way into them, causes the sides 
to fall in; thus, not only is an ever-increasing area of the hill-sides 
themselves ruined, but much damage is done lower down by the 
rush of water, and the deposit of silt carried down by it. This is 
an example on a small scale of what occurs, with such disastrous 
results, in the Southern Alps. The system adopted for the treat- 
ment of this evil may be briefly described as consisting of a series 
of obstacles erected in the bottom of the ravine, and behind 
which the rocks, gravel, and mud brought down by the water are 
retained. The slope of the bed being thus reduced, while, at the 
same time, it is raised, and consequently widened, by these de- 
posits, the unstable sides receive support; and when they have 
been sufficiently consolidated, they are planted up. In this 
manner the forces of nature are directed and employed by man, 
to restore the damage they caused, when uncontrolled; much in 
the same way as they are in the treatment of the dunes, described 
a few pages back. The weir we inspected is constructed of 
masonry, and has a total height of 65 ft., including 20 ft. of 
foundations. It is one of those made when works of this nature 
were undertaken for the first time in 1862; and it was in the 
nature of an experiment. It is now seen that its design is 
faulty in many ways, and it cannot be taken as a model of what 
such constructions should be.! 
1 On a future occasion the writer hopes to give a more complete account of 
the works undertaken in the Southern Alps, which are much more extensive 
and interesting than those which were visited near Barreges. 
