Origin of Species Variorum

→ on the prodigious 1859 1860 1861 1866

and on the great 1869 1872

→ gone on accumulating for a very 1859 1860 1861

to go on continuously accumulating during a very 1866 1869

gone on continuously accumulating during a 1872

→ in order to have given sufficient time 1859 1860

so that there may have been time sufficient 1861

so that there may be time sufficient 1866 1869

sufficient 1872

→ will generally have to 1859 1860 1861

will have to 1866 1869

must 1872

→ modification will have had to live on 1859 1860 1861

modification will have to live in 1866

change will have to live in 1869

change must have lived in 1872

→ fossiliferous formation 1859 1860

formation, fossiliferous throughout its thickness, 1861

formation, 1866 1869 1872

→ can only be accumulated 1859 1860 1861

fossiliferous throughout its thickness, can accumulate only 1866

fossiliferous throughout its entire thickness, can accumulate only 1869 1872

→ in order to enable 1859 1860

that 1861 1866 1869 1872

and likewise to reflect on the

~~great~~

great

changes of level, on the

extreme

inordinately great

change of climate, →on the prodigious lapse of time, all included within this same glacial period. Yet it may be doubted

whether,

whether

in any quarter of the world, sedimentary deposits,

including

including

fossil

fossil

remains,

remains,

remains ,

have gone on accumulating within the same area during the whole of this period. It is not, for instance, probable that sediment was deposited during the whole of the glacial period near the mouth of the Mississippi, within that limit of depth at which marine animals can

best flourish:

flourish;

for we know

that

what

great

vast

geographical changes occurred in other parts of America during this space of time. When such beds as were deposited in shallow water near the mouth of the Mississippi during some part of the glacial period shall have been upraised, organic remains will probably first appear and disappear at different levels, owing to the

migrations

migration

of species and to geographical changes. And in the distant future, a

geologist,

geologist

examining these beds,

would

might

be tempted to conclude that the average duration of life of the embedded fossils had been less than that of the glacial period, instead of having been really far greater, that

is,

extending from before the glacial epoch to the present day.

In order to get a perfect gradation between two forms in the upper and lower parts of the same formation, the deposit

will

must

have →gone on accumulating for a very long period, →in order to have given sufficient time for the slow process of

modification;

variation;

hence the deposit →will generally have to be a very thick one; and the species

under- going

undergoing

→modification will have had to live on the same

district

area

throughout

the

this

whole time. But we have seen that a thick →fossiliferous formation →can only be accumulated during a period of subsidence; and to keep the depth approximately the same, which is necessary →in order to enable