228
THE SEAS
fathoms in thickness, is sufcient to support the tremendous
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wealth of plant life that forms the pasturage of the sea,
and it is on the rain of dead plants and organisms that
have fed on them that the animals in the dark ocean depths
depend for their food.
It is hard for us to realize what the
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actual strength of the light is at different depths in the
sea;
but we might give as an example that in the open
waters of the English Channel the light at a depth of
about «
sixty feet corresponds to that found in the” heart of an
English beech wood and this is quite dim.
At such a depth
in the Mediterranean however the light would be
much Stronger, not only because the sun itself is so much
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moré powerful, but because the water is clear and lack…c
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that *sedimerrt of sand and mud that so
the
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water in the English Channel;
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The greatocean_s of the world are not merely masses of
.stationary
There exists within them a system
of
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gigantic currents whereby the water is continually cir—
culating and moving from place to place.
Am0ngst these currents is that known as the “ Gulf
Stream,” a name familiar to all on account of its bearing
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on
the climate of our islands.
In order to understand
roughly how the Gulf Stream takes its being and how it
moyes, it—is necessary to consider the whole of the North
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Atlantic ocean.
The Gulf Stream is a great oceanic current
that TeC€ives itsname from its place of Origin, the Gulf
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of Mexico, whence it issues through the Straits of Florida
stupendous river_of warm blue water fty miles in
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width and three hundred and fty fathoms deep:
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The forces that set and keep this great mass of water il!
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