To Charles Lyell 7 February 1
My dear Lyell
I am very much obliged for your note & the extract which have interested me extremely.2 I cannot disbelieve for a moment Agassiz on Glacial action after all his experience, as you say, & after that capital book with plates which he early published;3 as for his inferences & reasoning on the valley of the Amazon that is quite another question; nor can he have seen all the regions to which Mrs A. alludes.4
Her letter is not very clear to me & I do not understand what she means by “to a height of more than 3000 ft”.5 There are no erratic boulders (to which I particularly attended) in the low country round Rio. It is possible or even probable that this area may have subsided; for I cd detect no evidence of elevation or any tertiary formations or volcanic action.6
The Organ Mts. are from 6000 to 7000 ft in height & I am only a little surprized at their bearing the marks of glacial action.7 For some temperate genera of plants viz Vaccineum, Andromeda, Gaultheria, Hypericum, Drosera, Habenaria, inhabit these Mts. & I look at this almost as good evidence of a cold period as Glacial action.8 That there are not more temperate plants can be accounted for by the isolated position of these Mountains.
There are no erratic boulders on the Pacific coast North of Chiloe & but few glaciers in the Cordillera; but it by no means follows I think that there may not have been formerly gigantic glaciers on the Eastern & more humid side.9
In the 3rd Ed. of the Origin p 403, you will find a brief allusion, on authority of Mr D. Forbes, on the former much lower extension of glaciers in the equatorial Cordillera.10 Pray also look at p 407 at what I say on the nature of Tropical vegetation (which I could now much improve) during the glacial period.11 I feel a strong conviction that soon every one will believe that the whole world was cooler during the glacial period.12
Remember Hooker’s wonderful case recently discovered of the identity of so many temperate plants on the summit of Fernando Po & on the Mts. of Abyssynia:13 I look at as certain that these plants crossed the whole of Africa from E. to W. during this same period. I wish I had published a long chapter written in full & almost ready for the press on this subject which I wrote ten years ago.14 It was impossible in the Origin to give a fair abstract.15
My health is considerably improved, so that I am able to work nearly 2 hours a day & so make some little progress with my everlasting book on domestic varieties.16
You will have heard of my sister Catherine’s easy death last Friday morning.17 She suffered much, & we all look at her death as a blessing for there was much fear of prolonged & greater suffering. We are uneasy about Susan, but she has hitherto borne it better than we cd have hoped.18
Emma joins me in love to Lady Lyell19 & believe me dear Lyell | yours affectionately | Charles Darwin
Remember glacial action of Lebanon, when you speak of no glacial action in S. & on Himalaya & in S.E. Australia.—20
P.S. I have been very glad to see Sir C. Bunbury’s letter.21 If the genera which I name from Gardner are not considered by him, as usually temperate forms, I am of course silenced;22 but Hooker looked over the M.S chapter some ten years ago & did not score out my remarks on them,23 & he is generally ready enough to pitch into my ignorance, & snub me as I often deserve.— My wonder was how any, even so few, temperate forms reached the mountains of Brazil; & I supposed they travelled by the rather high land & ranges (name forgotten) which stretch from the Cordillera towards Brazil— Cordillera genera of Plants have, also, somehow reached the Silla of Caraccas.24
When I think of the vegetation of N. Zealand & W. coast of S. America, where glaciers now descend to, or very near, to the sea, I feel it rash to conclude that all Tropical forms wd be destroyed by a considerably cooler period under the Equator.—25
Discussion of Mrs Agassiz’s letter [to Mary Lyell, forwarded to CD] regarding S. American glacial action,
with comments on Bunbury’s letter on temperate plants.
Refers to opinions of Agassiz, David Forbes, Hooker, and CD on glacial period and glaciers.
Wishes he had published a long chapter on glacial period [Natural selection, pp. 535–66] written ten years ago.
Tells of death of his sister, Catherine, and other family matters.