DOI Page / Citation link:
https://doi.org/10.11588/diglit.5542#0323
Chap, xi.viii.]
OOLITIC FORMATION.
309
not account for until I found, further north, a large mass,
horizontally stratified, detached from the cliff itself, and
the intervening chasm gradually filling up with the same
substances, deposited by the water as it trickled down the
side, thus producing an appearance of vertical stratification.
Near this chasm the incrustations and stalactites overhang-
ing the cliff have assumed very singular forms, being
regularly jointed and curled under, like the feelers of an
encrinite, or the curled-up extremities of a star-fish. In
some places the saline springs, falling over the cliff, have
formed, by rapid evaporation, thin tubes of salt, full of
water, which, however, were too delicate and slender to bear
the slightest touch; a breath of wind would have dissolved
them.
While examining the various phamomena of these springs,
and particularly the basins in which the mineral waters were
collected, I observed a fact which seemed to throw light
on the cause and origin of the oolitic structure, where the
concentric layers have not been deposited round a pre-
existing nucleus. In some of these pools many little glo-
bular incrustations were floating on the surface, produced
by bubbles of gas which successively rose to the surface,
and which appeared to have been formed in the following
manner:—When the bubble comes in contact with the at-
mosphere, evaporation takes place, and the film of water,
which enclosed the gas, is replaced by a still thinner film
of the matter with which the water was saturated, and
which, from its extreme tenuity, continues for some time
floating on the surface, until it gradually acquires greater
solidity, from the cohesion of other matter contained in the
water. I saw many of these hard bubbles floating on the
surface, but of such a fine and delicate texture that they
did not bear any handling. By degrees, however, they
become thicker, and acquire greater strength, when their
specific gravity no longer allowing them to float, they sink
to the bottom of the pool; here they soon become ag-
glomerated together, some remaining hollow, and others
OOLITIC FORMATION.
309
not account for until I found, further north, a large mass,
horizontally stratified, detached from the cliff itself, and
the intervening chasm gradually filling up with the same
substances, deposited by the water as it trickled down the
side, thus producing an appearance of vertical stratification.
Near this chasm the incrustations and stalactites overhang-
ing the cliff have assumed very singular forms, being
regularly jointed and curled under, like the feelers of an
encrinite, or the curled-up extremities of a star-fish. In
some places the saline springs, falling over the cliff, have
formed, by rapid evaporation, thin tubes of salt, full of
water, which, however, were too delicate and slender to bear
the slightest touch; a breath of wind would have dissolved
them.
While examining the various phamomena of these springs,
and particularly the basins in which the mineral waters were
collected, I observed a fact which seemed to throw light
on the cause and origin of the oolitic structure, where the
concentric layers have not been deposited round a pre-
existing nucleus. In some of these pools many little glo-
bular incrustations were floating on the surface, produced
by bubbles of gas which successively rose to the surface,
and which appeared to have been formed in the following
manner:—When the bubble comes in contact with the at-
mosphere, evaporation takes place, and the film of water,
which enclosed the gas, is replaced by a still thinner film
of the matter with which the water was saturated, and
which, from its extreme tenuity, continues for some time
floating on the surface, until it gradually acquires greater
solidity, from the cohesion of other matter contained in the
water. I saw many of these hard bubbles floating on the
surface, but of such a fine and delicate texture that they
did not bear any handling. By degrees, however, they
become thicker, and acquire greater strength, when their
specific gravity no longer allowing them to float, they sink
to the bottom of the pool; here they soon become ag-
glomerated together, some remaining hollow, and others