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show how slowly they have been accumulated. Let him remember Lyell's profound remark that the thickness & extent of all sedimentary formations are the result & 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! Prof. Ramsay has given me the following measurements maximum thickness, generally from actual measurement, in a few cases from estimates of the each formation in Great Britain; & 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 & three - quarters British miles.

On the continent some formations are poorly represented in England, as thousands of feet in thickness, which are poorly represented in England.

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[there are two sets of pin holes where a note was attached here. Bottom of page excised with scissors where text was removed. The famous discussion of the denudation of the Weald (see Lyell 1833) is one page after this point in the draft.]

[pencil annotation in another hand:]

Charles Darwin