| → level, as well as the subsequent subaerial degradation. 1869 1872 |
| level. 1859 1860 1861 1866 |
|
| → OMIT 1869 1872 |
| judging from the researches of E. Forbes , we may conclude that 1859 1860 1861 |
| judging from the rescarches of E. Forbes , we may conclude that 1866 |
|
| → so many and such varied forms of life, as the more shallow seas; 1869 1872 |
| extremely few animals, 1859 1860 |
| few animals, 1861 1866 |
|
| → and the mass when upraised will give an imperfect record of the organisms which existed in the neighbourhood during the period of its accumulation. Or, 1872 |
| and the mass when upraised will give a most imperfect record of the forms of life which then existed; or, 1859 1860 |
| but it will not be, as we at last know from the telegraphic soundings, barren of life; consequently the mass when up-raised will give a most imperfect record of the forms of life which existed during the period of deposition. Or, 1861 |
| but it will not be, as we now know from telegraphic and other deep soundings, barren of life; consequently the mass when upraised will give a most imperfect record of the forms of life which existed during the period of deposition. Or, 1866 |
| and the mass when upraised will give an imperfect record of the organisms which existed throughout the world during the period of its accumulation. Or, 1869 |
|
|
consecutive. But we know, for instance, from Sir R.
great work on Russia, what wide gaps there are in that country between the superimposed formations; so it is in North America, and in many other parts of the world. The most skilful geologist, if his attention had been
to these large territories, would never have suspected
during the periods which were blank and barren in his own country, great piles of sediment, charged with new and peculiar forms of life, had elsewhere been accumulated. And
in each separate territory, hardly
idea can be formed of the length of time which has elapsed between the consecutive formations, we may infer that this could nowhere be ascertained. The frequent and great changes in the mineralogical composition of consecutive formations, generally implying great changes in the geography of the surrounding lands, whence the sediment
derived,
with the belief of vast intervals of time having elapsed between each formation. |
|
|
can, I think, see why the geological formations of each region are almost invariably intermittent; that is, have not followed each other in close sequence. Scarcely any fact struck me more when examining many hundred miles of the South American coasts, which have been upraised several hundred feet within the recent period, than the absence of any recent deposits sufficiently extensive to last for even a short geological period. Along the whole west coast, which is inhabited by a peculiar marine fauna, tertiary beds are so
developed, that no record of several
and peculiar marine faunas will probably be preserved to a distant age. A little reflection will explain
along the rising coast of the western side of South America, no extensive formations with recent or tertiary remains can anywhere be found, though the supply of sediment must for ages have been great, from the enormous degradation of the coast-rocks and from muddy streams entering the sea. The explanation, no doubt, is, that the littoral and sub-littoral deposits are continually worn away, as soon as they are brought up by the slow and gradual rising of the land within the grinding action of the coast-waves. |
|
| We may, I think,
conclude that sediment must be accumulated in extremely thick, solid, or extensive masses, in order to withstand the incessant action of the waves, when first upraised and during
oscillations of
→level, as well as the subsequent subaerial degradation. Such thick and extensive accumulations of sediment may be formed in two ways;
in profound depths of the sea, in which
→OMIT
the bottom will
inhabited by
→so many and such varied forms of life, as the more shallow seas;
→and the mass when upraised will give an imperfect record of the organisms which existed in the neighbourhood during the period of its accumulation. Or,
|
