The morning news. [volume] (Savannah, Ga.) 1887-1900, 1897-07-01

next, with the proper measurements, de-
termng the rate of growth.
On an average an inch year is about
the most rapid rate. This tremendous
growth of corals naturally depends upon
their getting out of their environment a
certain amount of carbonate of lime, of
which they build up their cells. The lime
is always in solution in the sea.
We find that in a square mile of sea
water 100 fathoms deep we have sixteen
tons of solid carbonate of lime in solution.
Spreading this over the surface of a
square mile we have a layer of carbonate
of lime 1-lO00O0 inch thick, or contracting
1t into a hundred yards square we will
have one-third of an inch thick. This has
has to be taken out of the water by the
cordls, and, of course is supplied to them
by the rivers that flow into the ocean.
There is a bank of coral rock upon the
sea bottom near the shores of many a
tropical island. Most of the Pacific Is
lands are volcanic. We find, however,
that the slope of the shores in deep water
is very gradual, which affords an oppor-
tunity for the growth of the coral
There are certain terms given to differ
ent kinds of reefs-barrier reefs, fringing
reef, and atoll Barrier and fringing reefs
are practically the same thing, only, In
the one case, the fringing reef is nearer
the shore and is accompanied by broad
platform running out from the shore to
the edge of the reef A barrier reef on
the other hand, is a barrier to the coast
as bordering Australia we have, fifty or
more miles from the coast, and deep water
in between, so that vessels can come in
between the barren reef and the coast
An atoll Is a circular barrier reef without
any land in the middle at ALA lagoon in
the middle is the open space and the outer
portion Of the reef or circle is the barrier
reef. They simply call it an atoll, from
the word atOll meaning to unite.
The extent of reefs varies. OF course,
sometimes we have only very little
patches, as in some of the West Indian
islands, while the barrier reef of Austria
liza is 1 900 miles long and forms a harbor
in Australia more than equal to the whole
eastern coast of the United States from
Florida to Newfoundland.
How did the coral get down to 1000 feet?
Darwin formulated the theory of coral
islands. The reefs are not found on steep
shores. We find them most commonly on
the slopes of volcanoes. We have open
ngs in an atoll where vessels can get into
the lagoon.
Murray's theory as to the formation of
coral islands is that we have volcano
from the bottom of the sea into
the air. The corals grow at the depth of
sixty to seventy feet and are broken up
and powdered, and the winds throw this
up and finally it accumulates and becomes
a mass, so that is is not reached except
in the very highest tides. This continuing,
we have a beach formed above the action
of the water; erything-cocoanuts and
nuts of other trees that are killed by the
action of salt water--is thrown up on this
beach, and gradually we have formed the
here; and once in a while ami
mails transported here will also gain
foothold and establish themselves.
Here is a volcano sticking out of the
water. The coral plants itself on the sides
or slopes of the volcano and grows up to
the surface. The ocean bed is gradually
sinking, and as it sinks, the corals keep
growing up to the surface all the time.
The sinking is generally much slower than
the growth of the coral. Consequently it
will grow laterally. AS this sinking goes
on we have here the fringing reef, here
the barrier reef, and the next slide we
have the atoll The mountain has gone
down out of sight. The shape of the
atoll depends on the shape of tine Volcano