220
THE BIOLOGY OF FISHES
mountain ranges and ice—covers. These conditions have
‘
prevailed since the beginning‘of the geological epochs‘, but
the lithosphere has become probably three times as thick
'
'
as it was then, Whilst parts of the land surface have been
rolled or folded together and other parts have separated from
,
—
one another.
At the earliest periods the lithosphere probably
':
covered the entire globe and above_it was a layer of water.
.
This agrees with the general belief among biologists, that
living organisms had their origins in the sea and that animals
'
preceded plants.
'
"
ï
This theory of the shifting of land-masses in the past has
been suggested by various geologists (VVettstein, Pickering,
'
Taylor, and others) and has been developed more especially
.
by Wegener (1912, 1922). As an example of what the
.
theory; means, the following illustration given by the last—
..
mentioned author may be Cited.
If» we eXamine' the southWest corner of Europe on the, map, it looks as if the Iberian
Peninsula Thas rotated down from the Bay of Biscay in a
'
southerly direction, with the result that the Pyrenees have
_
been folded together from- the level land previously there;
The point of the fold is in the north with the broader base
in the south;
Similarly, the great mountain ranges, Alps,
5
Himalayas, Rocky 'Mountains, etc.,, have come
'
fault or break in the magma whereby theneighbouring
land, it might be for hun‘dreds of miles around, has been
.
drawn together with thedierent;strata fol‘dëd
each other, nOt lying= over one jâ‘nOtherï
case
_
under the
rOlled -
'
back t0wards,
its—former “level and
the;
,
above Ÿ'the plains and valleys.
1
_
'_Again,:Whethe;greatiCe_—She€tscame down in the Glacial ,
:
_
down the lithosphere *
:
ÎSO “that»many' _“ parts ;o_f=the- land iwere ooded and deposits
:
'
'
“were
the ice receded, the land gfadually
: _
_
Î
…rOse,r:but-, notquite to,—its former level, Where the -deposits;
',
_
*
Q
' ,
The sliding—, theory of the Continents has thus …anw
…
Î_
important bearingontheinterpretation of fossil remainèî.
THE BIOLOGY OF FISHES
mountain ranges and ice—covers. These conditions have
‘
prevailed since the beginning‘of the geological epochs‘, but
the lithosphere has become probably three times as thick
'
'
as it was then, Whilst parts of the land surface have been
rolled or folded together and other parts have separated from
,
—
one another.
At the earliest periods the lithosphere probably
':
covered the entire globe and above_it was a layer of water.
.
This agrees with the general belief among biologists, that
living organisms had their origins in the sea and that animals
'
preceded plants.
'
"
ï
This theory of the shifting of land-masses in the past has
been suggested by various geologists (VVettstein, Pickering,
'
Taylor, and others) and has been developed more especially
.
by Wegener (1912, 1922). As an example of what the
.
theory; means, the following illustration given by the last—
..
mentioned author may be Cited.
If» we eXamine' the southWest corner of Europe on the, map, it looks as if the Iberian
Peninsula Thas rotated down from the Bay of Biscay in a
'
southerly direction, with the result that the Pyrenees have
_
been folded together from- the level land previously there;
The point of the fold is in the north with the broader base
in the south;
Similarly, the great mountain ranges, Alps,
5
Himalayas, Rocky 'Mountains, etc.,, have come
'
fault or break in the magma whereby theneighbouring
land, it might be for hun‘dreds of miles around, has been
.
drawn together with thedierent;strata fol‘dëd
each other, nOt lying= over one jâ‘nOtherï
case
_
under the
rOlled -
'
back t0wards,
its—former “level and
the;
,
above Ÿ'the plains and valleys.
1
_
'_Again,:Whethe;greatiCe_—She€tscame down in the Glacial ,
:
_
down the lithosphere *
:
ÎSO “that»many' _“ parts ;o_f=the- land iwere ooded and deposits
:
'
'
“were
the ice receded, the land gfadually
: _
_
Î
…rOse,r:but-, notquite to,—its former level, Where the -deposits;
',
_
*
Q
' ,
The sliding—, theory of the Continents has thus …anw
…
Î_
important bearingontheinterpretation of fossil remainèî.