the lower beds of a formation having been upraised, denuded, submerged, and then re-covered by the upper beds of the same formation,— facts, showing what wide, yet easily overlooked, intervals have occurred in its accumulation. In other cases we have the plainest evidence in great fossilised trees, still standing upright as they grew, of many long intervals of time and changes of level during the process of deposition, which would
never even never even 1859 1860 1861 1866 1869 | not 1872 |
have been
suspected, suspected, 1859 1860 1861 1866 1869 | sus- pected, 1872 |
had not the trees
chanced to have chanced to have 1859 1860 1861 1866 1869 |
OMIT 1872 |
been preserved:
thus thus 1860 1861 1866 1869 1872 | thus, 1859 |
Sir C. Sir C. 1866 1869 1872 | Messrs. 1859 1860 1861 |
Lyell and
Dr. Dawson Dr. Dawson 1866 1869 1872 | Dawson 1859 1860 1861 |
found carboniferous beds 1400 feet thick in Nova Scotia, with ancient root-bearing strata, one above the
other, other, 1859 1860 1861 1866 1869 | other 1872 |
at no less than sixty-eight different levels. Hence, when the same species
occur occur 1859 1860 1861 1866 1869 | occurs 1872 |
at the bottom, middle, and top of a formation, the probability is that
they have they have 1859 1860 1861 1866 1869 | it has 1872 |
not lived on the same spot during the whole period of deposition, but
have have 1859 1860 1861 1866 1869 | has 1872 |
disappeared and reappeared, perhaps many times, during the same geological period.
So that, if such species So that, if such species 1866 1869 |
So that if such species 1859 1860 1861 |
Consequently if it 1872 |
were to undergo a considerable amount of modification during
any any 1859 1860 1861 1866 1869 |
the deposition of any 1872 |
one geological
period, period, 1859 1860 1861 1866 1869 | formation, 1872 |
a section would not
probably probably 1859 1860 1861 1866 | probably 1869 1872 |
include all the fine intermediate gradations which must on
my my 1859 1860 1861 1866 | our 1869 1872 |
theory have
existed existed 1859 1860 1861 1866 1869 | existed, 1872 |
between them, between them, 1859 1860 1861 1866 1869 | between them, 1872 |
but abrupt, though perhaps
....... 1861 1866 1869 1872 | very 1859 1860 |
slight, changes of form. |
It is all-important to remember that naturalists have no golden rule by which to distinguish species and varieties; they grant some little variability to each species, but when they meet with a somewhat greater amount of difference between any two forms, they rank both as species, unless they are enabled to connect them together by
the closest the closest 1866 1869 1872 | close 1859 1860 1861 |
intermediate
gradations. gradations. 1859 1860 1861 1866 1869 | gradations; 1872 |
And And 1859 1860 1861 1866 1869 | and 1872 |
this this 1859 1860 1861 1866 1869 | this, 1872 |
from the reasons just
assigned assigned 1859 1860 1861 1866 1869 | assigned, 1872 |
we can seldom hope to effect in any one geological section. Supposing B and C to be two species, and a third, A, to be found in an
underlying underlying 1859 1860 1861 1866 |
older and underlying 1869 1872 |
and older bed; and older bed; 1861 1866 |
bed; 1859 1860 1869 1872 |
even if A were strictly intermediate between
|