—
14
Introduction
;
The average depth of the oceans is 12,500 feet (nearly 2% miles)
‘
compared with an average height for the land of a mere 2,500 feet.
And at one of ‘ the deepest points, the Marianas Trench olï the
Philippines, the ocean oor lies over 36,000 feet beneath the surface,
deep enough to take the world’s highest mountain with some 7,000
feet to spare. At this great depth the water with its density of 64
pounds per cubic foot£»èxertS an overallipressure of some 7 tons per
square inch compared with an atmospheric pressure
at the surface of
only 15 ounds per square ih0h. However the Earth’s ocean canopy
is by no means u'niform; there are dilferent layers accordingto
temperature and salinity which together with currents add up to a
structure that still dees
.
«
The continents [seem to be nothing -more than large islands
scattered in an even larger global ocean…The Earth has»three major
oœas—thePacic, theAtlanti0 and the Indian—all of which share
but …di‘er,;markedly in…siz‘e and—shape.
The—Pacic Ocean dominates the Earth,-covering nearly a third of
its surface. Roughlycircular, its area at 64 million squaremiles, is
just
that of the »_S—shaped Atlantic or the oval Indian
Oceans—the Atlantic stretches over, some 31 million…square ;,miles
and the
miles. _, ; _
…In’addition to the three
maps of the world
show-a further
Antartic and Arctic
as
numerous—seas… These distinctions_àreas much accidents of history
as anything
of_t«three
groups :— marginal
oceans abyiisland arcs;
shallow
and deep
covering true :océa“nic parts} of the _.Earthîs
oceans,»the Arctic is, generally, considered {to be an?eXtensiori:,ofæthe
;
Atlantic Ocean and
to
three -
major ;oceans. Therefoæ, alth0ugh arbit‘rary'llinœ entending,.towards
the South
separate
‘
Cape of Good! Hope-(209- East) and from the
(1479 East), and
l?acic at -îlG‘ape Horn
(70° WeSt), the major. part of the :‘âEûfhîs sutfaceê is covered by »a
continuous mass of,water,a truly global ocean.
‘-‘a_>
‘ —
What is
to moVe
ocean
First comes
the continental shelf
witha;gradient of about 1 in…500
depth of 430 feet, although
limit,
14
Introduction
;
The average depth of the oceans is 12,500 feet (nearly 2% miles)
‘
compared with an average height for the land of a mere 2,500 feet.
And at one of ‘ the deepest points, the Marianas Trench olï the
Philippines, the ocean oor lies over 36,000 feet beneath the surface,
deep enough to take the world’s highest mountain with some 7,000
feet to spare. At this great depth the water with its density of 64
pounds per cubic foot£»èxertS an overallipressure of some 7 tons per
square inch compared with an atmospheric pressure
at the surface of
only 15 ounds per square ih0h. However the Earth’s ocean canopy
is by no means u'niform; there are dilferent layers accordingto
temperature and salinity which together with currents add up to a
structure that still dees
.
«
The continents [seem to be nothing -more than large islands
scattered in an even larger global ocean…The Earth has»three major
oœas—thePacic, theAtlanti0 and the Indian—all of which share
but …di‘er,;markedly in…siz‘e and—shape.
The—Pacic Ocean dominates the Earth,-covering nearly a third of
its surface. Roughlycircular, its area at 64 million squaremiles, is
just
that of the »_S—shaped Atlantic or the oval Indian
Oceans—the Atlantic stretches over, some 31 million…square ;,miles
and the
miles. _, ; _
…In’addition to the three
maps of the world
show-a further
Antartic and Arctic
as
numerous—seas… These distinctions_àreas much accidents of history
as anything
of_t«three
groups :— marginal
oceans abyiisland arcs;
shallow
and deep
covering true :océa“nic parts} of the _.Earthîs
oceans,»the Arctic is, generally, considered {to be an?eXtensiori:,ofæthe
;
Atlantic Ocean and
to
three -
major ;oceans. Therefoæ, alth0ugh arbit‘rary'llinœ entending,.towards
the South
separate
‘
Cape of Good! Hope-(209- East) and from the
(1479 East), and
l?acic at -îlG‘ape Horn
(70° WeSt), the major. part of the :‘âEûfhîs sutfaceê is covered by »a
continuous mass of,water,a truly global ocean.
‘-‘a_>
‘ —
What is
to moVe
ocean
First comes
the continental shelf
witha;gradient of about 1 in…500
depth of 430 feet, although
limit,