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18 MODE OF ACCELERATING
under-strata. On the contrary, in Savoy,
strata of similar formations occur nearly vertical,
and frequently conformable to the range
and dip of the granitic formations. These
facts would prove that the causes which
elevated the granite, have acted at different
epochs on various parts of the globe, unless
we are prepared to admit, that calcareous
formations, containing similar organic remains,
were not contemporaneous in different
countries, a supposition not altogether
void of probability.
That side of the Col de Balme which
declines south-west to the village of Tour,
is celebrated for the excellence of its herbage;
several rare and beautiful Alpine plants
also flourish there. In a ravine near Tour, a
deep section is made in a bed of very dark
schist, which was covered with a saline ef-
florence on many parts of its surface ; and
our guide informed us, that the chamois
frequently descended to lick the salt. It is
from this bed that the inhabitants procure
the black earth which they sprinkle over
the snow, to accelerate its solution in the
spring. As the summers in this elevated
situation are of short duration, it is of great
importance to save time in getting their
seed into the ground, and it was probably
accident which first discovered to them a
fact now well known in natural philosophy,
that dark surfaces are sooner heated by the
sun’s rays than white ones. It was proved
by the experiments of Dr. Franklin, that
black cloth laid upon snow, caused it to
melt faster than where it was uncovered,by
absorbing the sun’s rays, which are in a
great measure reflected from the surface of
the snow. The simple process of sprinkling
the surface of their fields with this
black earth, makes the snow melt many
days sooner than it would otherwise d o ;
but our guide informed us, it was sometimes
a tedious labour, for if any fresh
snow should fall, or be drifted over the
black earth, the operation must be repeated.
We saw several heaps of this black earth
collected near the cottages, to be ready for
the following spring. I wished to know
what kind of explanation our guide would
give of the action of the earth in dissolving
the snow, as he had constantly seemed
desirous of impressing us with the idea o f
his great knowledge. To my inquiry, in
what manner the effect was produced, he
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