From Archibald Geikie   24 December 1871

My dear M^r. Darwin

You confer the favour on me instead of receiving it from me by writing to me such a request as is contained in your note of yesterday.¹ I only wish that anything written by me would be likely to be of any service in the enquiry you are carrying on— By today’s post I send for your acceptance a copy of the only paper of mine bearing on the subject.² You will see from it that I do not enter at all into the question, how flat surfaces are wasted. I deal in that paper with the sum total of denudation over the surface of a country, my object being to shew the unequal rate of waste and the way in which the total amount of material removed from a land surface may be estimated.

Believe me to remain | Yours very truly | Arch Geikie

Charles Darwin Esq | F.R.S. &^c. &^c.