Comparison with 1859 |
|
to last to an
age, age, 1859 | age 1860 1861 1866 1869 1872 |
as distant in futurity as the secondary formations lie in the past, only
during periods of subsidence. These periods of subsidence would be separated from each other by enormous
intervals,
during
which the area would be either stationary or rising; whilst rising, each
fossiliferous formation
would
be destroyed, almost as soon as accumulated, by the incessant coast-action, as we now see on the shores of South America.
↑1 blocks not present in 1859 1860 1861 1866 1869; present in 1872 | Even throughout the extensive and shallow seas within the archipelago, sedimentary beds could hardly be accumulated of great thickness during the periods of elevation, or become capped and protected by subsequent deposits, so as to have a good chance of enduring to a very distant future.
|
During the periods of subsidence
there would probably be much extinction of life; during the periods of elevation, there would be much variation, but the geological record would then be least
perfect. |
|
It may be doubted whether the duration of any one great period of subsidence over the whole or part of the archipelago, together with a contemporaneous accumulation of sediment, would
exceed the average duration of the same specific forms; and these contingencies are indispensable for the preservation of all the transitional gradations between any two or more species. If such gradations were not fully
preserved, transitional varieties would merely appear as so many distinct
species. It is,
also,
probable that each great period of subsidence would be interrupted by oscillations of level, and that slight climatal changes would intervene during such lengthy periods; and in these cases the inhabitants of the archipelago would have to
migrate, and no closely consecutive record of their modifications could be preserved in any one formation. |
|
Very many of the marine inhabitants of the archipelago now range thousands of miles beyond its confines; and analogy leads me to
believe
that it would be chiefly these far-ranging species
which
would oftenest produce new varieties; and the varieties would at first generally
be local or confined to one place, but if possessed
|
to last to an
age age 1860 1861 1866 1869 1872 | age, 1859 |
as distant in futurity as the secondary formations lie in the past,
only only 1859 1860 1861 |
would generally be formed in the archipelago only 1866 1869 1872 |
during periods of subsidence. These periods of subsidence would be separated from each other by
enormous enormous 1859 1860 1861 1866 | immense 1869 1872 |
intervals, intervals, 1859 1860 1861 | intervals 1866 1869 1872 |
during during 1859 1860 1861 |
of time, during 1866 1869 1872 |
which the area would be either stationary or rising; whilst rising,
each each 1859 1860 | the 1861 1866 1869 1872 |
fossiliferous
formation formation 1859 1860 | formations 1861 1866 1869 1872 |
would would 1859 1860 |
on the steeper shores would 1861 1866 1869 1872 |
be destroyed, almost as soon as accumulated, by the incessant coast-action, as we now see on the shores of South
America. America. 1859 1860 1872 |
America; even throughout the extensive and shallow seas within the archipelago sedimentary beds could not, during the periods of elevation, be accumulated of great thickness, or become capped and protected by subsequent deposits, so as to have a good chance of enduring to an extremely distant future. 1861 1866 |
America; even throughout the extensive and shallow seas within the archipelago sedimentary beds could hardly be accumulated of great thickness during the periods of elevation, or become capped and protected by subsequent deposits, so as to have a good chance of enduring to a very distant future. 1869 |
↑1 blocks not present in 1859 1860 1861 1866 1869; present in 1872 | Even throughout the extensive and shallow seas within the archipelago, sedimentary beds could hardly be accumulated of great thickness during the periods of elevation, or become capped and protected by subsequent deposits, so as to have a good chance of enduring to a very distant future.
|
During the periods of
subsidence subsidence 1859 1860 | subsidence, 1861 1866 1869 1872 |
there would probably be much extinction of life; during the periods of elevation, there would be much variation, but the geological record would then be
least least 1859 1860 1861 1866 1869 | less 1872 |
perfect. |
|
It may be doubted whether the duration of any one great period of subsidence over the whole or part of the archipelago, together with a contemporaneous accumulation of sediment, would
exceed
exceed
1859 1860 1866 1869 1872 | exceed 1861 |
the average duration of the same specific forms; and these contingencies are indispensable for the preservation of all the transitional gradations between any two or more species. If such gradations were not
fully fully 1859 1860 | all fully 1861 1866 1869 1872 |
preserved, transitional varieties would merely appear as so many
distinct distinct 1859 1860 1861 1866 |
new and distinct 1869 |
new, though closely allied 1872 |
species. It
is, is, 1859 1860 | is 1861 1866 1869 1872 |
also, also, 1859 1860 | also 1861 1866 1869 1872 |
probable that each great period of subsidence would be interrupted by oscillations of level, and that slight climatal changes would intervene during such lengthy periods; and in these cases the inhabitants of the archipelago would
have to have to 1859 1860 | have to 1861 1866 1869 1872 |
migrate, and no closely consecutive record of their modifications could be preserved in any one formation. |
|
Very many of the marine inhabitants of the archipelago now range thousands of miles beyond its confines; and analogy
leads me to leads me to 1859 1860 |
plainly leads to the 1861 1866 1869 1872 |
believe believe 1859 1860 | belief 1861 1866 1869 1872 |
that it would be chiefly these far-ranging
species species 1859 1860 1861 | species, 1866 1869 1872 |
which which 1859 1860 1861 |
though only some of them, which 1866 1869 1872 |
would oftenest produce new varieties; and the varieties would at first
generally generally 1859 1860 1861 1866 1869 | generally 1872 |
be local or confined to one place, but if possessed
|