Origin of Species Variorum

→ by atmospheric degradation and by the action of the sea during 1866 1869 1872

during 1861

→ a long period. 1866 1869 1872

an extremely long period,— a consideration which I formerly overlooked. 1861

→ also expresses his belief that 1866 1869 1872

in commenting on this subject, states that he believes the entire destruction of any 1861

→ rarely been completely destroyed. 1866 1869 1872

been of rare occurrence. 1861

→ these latter rocks 1869 1872

rocks of this nature must 1866

→ denuded on 1866 1869

stript of their covering to 1872

↑ 4 blocks not present in 1859 1860 1866 1869 1872; present in 1861

My remarks apply solely to beds rich in fossils: I have admitted that sediment accumulated in extremely thick, solid, or extensive masses would escape denudation. The point in question is, whether widely extended formations, rich in fossils, and of sufficient thickness to last for a long period, would be formed except during periods of subsidence? My impression is that this has rarely been the case. As the subject of complete denudation has been broached by Mr. Hopkins, I may remark that all geologists, excepting the few who believe that they see in the metamorphic schists and plutonic rocks the heated primordial nucleus of the globe, will probably admit that rocks of this nature must have been largely denuded.

→ whilst uncovered; 1866 1869 1872

in a naked condition; 1861

→ protecting mantle of rock 1869 1872

mantle 1861

protecting mantle 1866

→ OMIT 1869 1872

such rocks as 1861 1866

→ of this nature as 1866 1869 1872

as 1861

overlying

over- lying

formations, so that it would run a good chance of being worn away →by atmospheric degradation and by the action of the sea during subsequent oscillations of level. It

has

has,

been

however, been

suggested by Mr. Hopkins, that if one part of the area, after rising and before being denuded, subsided, the deposit formed during the rising movement, though not thick, might

become

afterwards become

protected by fresh accumulations, and thus be preserved for →a long period.

Mr.

Hopkins,

Hopkins

→also expresses his belief that sedimentary

bed

beds

of considerable horizontal extent

....

have →rarely been completely destroyed. But all geologists, excepting the few who believe that our present metamorphic schists and plutonic rocks once formed the primordial nucleus of the globe, will

probably

....

admit that →these latter rocks have been →denuded on an enormous

extent.

scale.

↑ For it is scarcely possible that

these

such

rocks

should

could

have been solidified and crystallized →whilst uncovered; but if the metamorphic action occurred at profound depths of the ocean, the former →protecting mantle of rock may not have been

thick.

very thick.

Admitting then that →OMIT gneiss, mica-schist, granite, diorite,

&c,

&c.,

were once necessarily covered up, how can we account for the

extensive

naked

and

naked

extensive

areas of such rocks in many parts of the world, except on the belief that they have subsequently been completely denuded of all overlying strata? That such extensive areas do exist cannot be

doubted;

doubted:

the granitic region of Parime is described by Humboldt as being at least nineteen times as large as Switzerland. South of the

Amazon

Amazon,

Boué colours an area composed of

such

....

rocks →of this nature as equal to that of Spain, France, Italy, part of Germany, and the British Islands, all conjoined. This region has not been carefully explored, but from the concurrent testimony of travellers, the granitic area

must be

very

large;

large:

thus, Von Eschwege