Dear Sir

I have just read your notice on bent cleavage;² & it has occurred to me that you might possibly like to hear that I observed the same fact in Chili. You will find a brief notice of this subject in my Geological Observations on South America 1846 footnote page 160.³ In case you thought it worth while to refer to the passage, you will find a copy of this book at the Geolog. Soc.⁴ I have suggested as a conjectural explanation the action of earthquakes. I presume that in a district lying for instance south of a volcanic focus the vibrations w^d travel across the country in a nearly regular manner.

Pray do not trouble yourself to acknowledge the receipt of this as I do not know whether it is worth sending, & I beg leave to remain, dear Sir, | yours faithfully | Charles Darwin