Origin of Species Variorum

→ countries! Professor Ramsay has given me the maximum thickness, in most cases from actual measurement, in a few cases from estimate, of each formation in different parts of Great Britain; and this is the result:— Feet. Palæozoic strata (not including igneous beds) .. 57,154 Secondary strata .. .. .. .. .. .. .. 13,190 Tertiary strata .. .. .. .. .. .. .. .. 2,240 1859

countries! Professor Ramsay has given me the maximum thickness, in most cases from actual measurement, in a few cases from estimate, of each formation in different parts of Great Britain; and this is the result:— Feet. Palæozoic strata (not including igneous beds) .. 57,154 Secondary strata .. .. .. .. .. .. .. 13,190 Tertiary strata .. .. .. .. .. .. .. 2,240 1860

countries! Professor Ramsay has given me the maximum thickness, in most cases from actual measurement, in a few cases from estimate, of each formation in different parts of Great Britain; and this is the result:— Feet. Palæozoic strata (not including igneous beds) .. 57,154 Secondary strata .. .. .. .. .. .. .. 13,190 Tertiary strata .. .. .. .. .. .. .. 2,240 1866

↑ 1 blocks not present in 1859 1860 1861 1866; present in 1869 1872

Professor Ramsay has given me the maximum thickness, in most cases from actual measurement, in a few cases from estimate, of each formation in different parts of Great Britain; and this is the result:— Feet. Palæozoic strata (not including igneous beds) .. 57,154 Secondary strata .. .. .. .. .. .. .. 13,190 Tertiary strata .. .. .. .. .. .. .. .. 2,240

→ periods. 1859 1860 1861 1866 1869

periods of enormous length. 1872

→ Good observers have estimated that sediment is deposited by the great Mississippi river at the rate of only 600 feet in a hundred thousand years. 1859 1860 1861 1866

The consideration of these various facts impresses the mind almost in the same manner as does the vain endeavour to grapple with the idea of eternity. 1872

→ may be quite erroneous; 1859

has no pretension to strict exactness; 1860 1861 1866

are the result and measure of the degradation which the earth's crust has elsewhere suffered. And what an amount of degradation is implied by the sedimentary deposits of many → countries! Professor Ramsay has given me the maximum thickness, in most cases from actual measurement, in a few cases from estimate, of each formation in different parts of Great Britain; and this is the result:— Feet. Palæozoic strata (not including igneous beds) .. 57,154 Secondary strata .. .. .. .. .. .. .. 13,190 Tertiary strata .. .. .. .. .. .. .. .. 2,240 ↑ — making altogether 72,584 feet; that is, very nearly thirteen and three-quarters British miles. Some of

the

these

formations, which are represented in England by thin beds, are thousands of feet in thickness on the Continent. Moreover, between each successive formation, we have, in the opinion of most geologists,

~~enormously long~~

enormously long

blank →periods. So that the lofty pile of sedimentary rocks in

Britain

Britain,

gives but an inadequate idea of the time which has elapsed during their

accumulation.

~~yet~~

~~what~~

~~time~~

~~this~~

~~must~~

~~have~~

~~consumed!~~

→Good observers have estimated that sediment is deposited by the great Mississippi river at the rate of only 600 feet in a hundred thousand years. This estimate →may be quite erroneous; yet, considering over what wide spaces very fine sediment is transported by the currents of the sea, the process of accumulation

over

any one

extensive area

area

must be extremely slow.

But the amount of denudation which the strata have in many places suffered, independently of the rate of accumulation of the degraded matter, probably offers the best evidence of the lapse of time. I remember having been much struck with the evidence of denudation, when viewing volcanic islands, which have been