Comparison with 1861 |
|
aware that two palæontologists, whose opinions are worthy of much deference, namely Bronn and Woodward,
have concluded that the average duration of each formation is twice or thrice as long as the average duration of specific forms. But insuperable difficulties, as it seems to me, prevent us coming
to any just conclusion on this head. When we see a species first appearing in the middle of any formation, it would be rash in the extreme to infer that it had not elsewhere previously existed. So again when we find a species disappearing before the uppermost
layers have been deposited, it would be equally rash to suppose that it then became wholly
extinct. We forget how small the area of Europe is compared with the rest of the world; nor have the several stages of the same formation throughout Europe been correlated with perfect accuracy. |
|
With
marine animals of all kinds,
we may safely infer
a large amount of migration during
climatal and other changes; and when we see a species first appearing in any formation, the probability is that it only then first immigrated into that area. It is well known,
for instance, that several species appeared
some-what some-what 1861 1866 1869 | somewhat 1859 1860 1872 |
earlier in the palæozoic beds of North America than in those of Europe; time having apparently been required for their migration from the American to the European seas. In examining the latest deposits of
various quarters of the world, it has everywhere been noted, that some few still existing species are common in the deposit, but have become extinct in the immediately surrounding sea; or, conversely, that some are now abundant in the neighbouring sea, but are rare or absent in this particular deposit. It is an excellent lesson to reflect on the ascertained amount of migration of the inhabitants of Europe during the
glacial glacial 1861 1866 1869 1872 | Glacial 1859 1860 |
period,
which forms only a part of one whole geological
period; period; 1859 1861 1866 1869 1872 | period: 1860 |
|
aware that two palæontologists, whose opinions are worthy of much deference, namely Bronn and
Woodward, Woodward, 1859 1860 1861 1872 | Wood-ward, 1866 | Wood- ward, 1869 |
have concluded that the average duration of each formation is twice or thrice as long as the average duration of specific forms. But insuperable difficulties, as it seems to me, prevent us
coming coming 1859 1860 1861 | from coming 1866 1869 1872 |
to any just conclusion on this head. When we see a species first appearing in the middle of any formation, it would be rash in the extreme to infer that it had not elsewhere previously existed. So again when we find a species disappearing before the
uppermost uppermost 1859 1860 1861 | last 1866 1869 1872 |
layers have been deposited, it would be equally rash to suppose that it then became
wholly wholly 1859 1860 1861 | wholly 1866 1869 1872 |
extinct. We forget how small the area of Europe is compared with the rest of the world; nor have the several stages of the same formation throughout Europe been correlated with perfect accuracy. |
|
With With 1859 1860 1861 1866 1869 |
We may safely infer that with 1872 |
marine animals of all
kinds, kinds, 1859 1860 1861 1866 1869 | kinds 1872 |
we may safely infer we may safely infer 1859 1860 1861 1866 1869 |
there has been 1872 |
a large amount of migration
during during 1859 1860 1861 1866 1869 | due to 1872 |
climatal and other changes; and when we see a species first appearing in any formation, the probability is that it only then first immigrated into that area. It is
well known, well known, 1859 1860 1861 1866 1869 | well-known, 1872 |
for instance, that several species appeared
somewhat somewhat 1859 1860 1872 | some-what 1861 1866 1869 |
earlier in the palæozoic beds of North America than in those of Europe; time having apparently been required for their migration from the American to the European seas. In examining the latest deposits
of of 1859 1860 1861 | in 1866 1869 1872 |
various quarters of the world, it has everywhere been noted, that some few still existing species are common in the deposit, but have become extinct in the immediately surrounding sea; or, conversely, that some are now abundant in the neighbouring sea, but are rare or absent in this particular deposit. It is an excellent lesson to reflect on the ascertained amount of migration of the inhabitants of Europe during the
Glacial Glacial 1859 1860 | glacial 1861 1866 1869 1872 |
period, period, 1859 1860 1861 | period; 1866 | epoch, 1869 1872 |
which forms only a part of one whole geological
period: period: 1860 | period; 1859 1861 1866 1869 1872 |
|