, 1877-12-29

worn down by motion on the beach. With
these rounded grains are mixed portions of
sea-egg spines minute fragments Of coral ;
pieces of peculiar sea plants which extract
lime from the sea, stony vegetables as we
may call them, growing over the rocks
and the dead cOrals in white or red pat
ches and frequently countless shells of
small creatures called foraminifera. shells
having the form of microscopic biscuits.
Sometimes the sand consists entirely of
the scales of one particular sea-weed, a
weed which grows first green, but gradu-
ally filling up with lime its leaves become
white and hard, it finally dies, falls down
and breaks up, adding its minute contribu-
ton to the sand Of thc!shallow where itgrew.
Thus it is that countless animals and
plants are continually extracting lime
from the sea and leaving it behind them in
their death as a legacy added to the accu-
mulating masses of sand around our shores.
AS WE walk along the beach we FREE
quentiy perceive that large quantities of
the sand have been cemented firmly to.
gethcr and form stone: al observation
which prepares the way for another eXcur-
81 N which we will request the very
patient rradef who has come thus tar TO
make ia our company. From the appear.
ance of the lime stone and mari rocks OF
Santa Cruz we have a suspicion that they
have in some former years Neen accumu-
lated under the sea like the sands and
reefs of which we have been Just speaking,
and that they have by a subsequent up
lifting been brought to form the hills and
plains which we now see. To study this
question we mnst visit one of those places
when he solid structure Of the island has
ben laid open, either by the bea ting of
the waves on the shore, or by the hand
of man in other words we must visit the
cliffs on the coast, or the quarries and
road cuttings on the hill sides. A spot
lying on a main road and therefore fAmili-
or to mary will best serve our purpose.
Let US then pay a visit to Anna's Hope
and study the banks in the road cutting.
Here we will ind hat the rocks are ar
ranged in layers and contain corals here
and there. A close examination shows
that many layers are full of sand-grains
end little pebbles rounded in the waves.
One bed moreover contains myTiads OF the
little foraminifera already mentioned az
found on our beaches. Thus we ind that
the real origin OF limestone is 10 the sea.
1t is a striking reflection that a conside'
rable portion of the mass OF our island is
formed Of nothing else than layers OF the
remains of sea creatures piled over each
other to thickness of six ar seven hundred
feet, yet such is the fact. Since
their accumulation in the sea theyy
have been lifted, probably at q very slow
rate, and valleys have been cut out
by the rains, vegetation has covered the
slopes and rounded SUBMITS, aud it is On'y
by observation directed to the purpose
that we find out the real history of these
hills and da!es. Such then as illustrated
in our own island is the history OF lime
stones. Is this the history also of Marbles
aud other crystallized llmestones which
contain no trace of ~fosslls2 Such lime
stones arc always found near rocks which
have been changed by subterranean fire,
and biologists soon began to suspect that
these crystallized limestones had been form
ed from the common stone by the &C.
ton of heat but if so why had not the
heat driven off the ca"b1nic acid
as we know it does in the lime-kiln 1t
was assumed that perhaps the great pres
sure of the rocks over the limestone proven
ted the escape of the gas. A famous che
- ~ -. I'LL xo,f &hic fho0Pu m