RECORD: Darwin, C. R. 1858.12.23. If a cliff of 500 ft high recedes 1 inch in century, how long would it take to each back a cliff one yard high. CUL-DAR205.9.341. (John van Wyhe ed., 2002-. The Complete Work of Charles Darwin Online, http://darwin-online.org.uk/)
REVISION HISTORY: Transcribed by Christine Chua and edited by John van Wyhe 10.2021. RN2
NOTE: See record in the Darwin Online manuscript catalogue, enter its Identifier here. Reproduced with permission of the Syndics of Cambridge University Library and William Huxley Darwin. The volume CUL-DAR205.9 contains notes on palaeontology and geology [regarding theory of evolution].
[341]
Dec. 23/58
63360 inches in one mile [x] 22 miles [=] 126720 [+] 126720. [=] 1393920 inches in whole distance [x] 220 years which 1 mile would require [=] 27878400 [+] 2787840 [=]
306,662,400 years for denudation of Weald.
If a cliff of 500 ft high recedes 1 inch in century, how long would it take to each back a cliff one yard high, one yard backwards? a little more than 21 years—
Say between 21 & 22 years 21 3/5
[Figures and calculations not transcribed]
This note is related to Darwin's famous estimate the age of the Earth based on the rate of the denudation of the Weald in Origin, pp. 285-286.
Citation: John van Wyhe, ed. 2002-. The Complete Work of Charles Darwin Online. (http://darwin-online.org.uk/)
File last updated 15 January, 2026