…zoz_ç ,_:
THE BIOLOGY OF Frsnss“
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generally accepted, that the earth is much older than
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arid thegeologists of his time c0uld have believed. The
,
,
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following table (from A. Wegener, 1922) gives a summary .
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of the most recent estimates.
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=;Ït
.
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Time elapsed since the beginning of the
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Palæozoic period
.
.
.
.
500 million years
Mesozoic period
.
.
_.
.
.
‘
50
,,
,,'
’
_Cenozoic—
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.,
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,.
,
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Tertiary period ..
.
.
.
,
15
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j
.
,
—Eoœne,period
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.
.
..
zo
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‘
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_
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.'Oligocene period
.
.
.
.
.'
8
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,
:)
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‘
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,.
—.
..
6
,;,_",,
_
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Î
,
Pliocene period, .
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.'
.
=
2—4
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,
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Diluviumperiod
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.
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Post—diluviüm:period
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.
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10—50 thousand years
,
_
Palæ‘oZQic.period lay
age
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. _' ; Î _— of
_hegÿÿ _metals,_. lead, -
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—
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From ÿi ,
follOWig .ræb1è, 1shoWing — the
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', principal foSSil,shes—SO far discovered in the earlie'st forma— '
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tions,. it Willbe seen that the ‘age of shes may be placed
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,
_
,
400 millions of years.
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Fossils.
Country.
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-
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,
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,_Êÿ_
î)..î;.A1g‘cnkian;.
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.
—
.
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.' ‘ Cambrian '.
Fish remains
Rocky Mts., Canada
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Silurian
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Placoderms (P)
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Colorado, U_.S.A: '
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g
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Scotland,SWeden_—,
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’,
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Birkeniidæ
Seoànda‘NorwiäY;Canada,
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? i..î’Devonim
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Arthrodira,
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Europe1\Uämenca
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Scotland_ ?
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Pa]äùscidæë.î‘=—î£:'f‘i Eu“opeN5îê :
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SAïnca>Austfaha ' ï
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;î.fîCarb0mfefousCladoseïacheŒîasmo-NAmema
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Eur0pe, Aus-.
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…
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Otherformsoccnrm the D'eV0nian
many more
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but;those mentioned Will be
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pietuæ:bfïhe'01dæt.'shes“. Through
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as
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:f_ ._ such,
appear_üh”cil
{it,_;hæ=:gbæg
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generally '_ïbelieved, ibm. With someç=_'opposian_.;from,:
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