In the Cordillera, I estimated one mass of conglomerate at ten thousand feet; and although conglomerates have probably been accumulated at a quicker rate than finer sediments, yet from being formed of worn and rounded pebbles, each of which bears the stamp of time, they are good to show how slowly the mass must have been heaped together.

Professor Ramsay has given me the maximum thickness, from actual measurement in most cases, of the successive formations in DIFFERENT parts of Great Britain; and this is the result:-- Feet Palaeozoic 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 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, blank periods of enormous length.

So that the lofty pile of sedimentary rocks in Britain gives but an inadequate idea of the time which has elapsed during their accumulation.

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.
Nevertheless this impression is partly false.