My dear Lyell

It was very good of you to write me so long a letter which has interested me much; I sh^d. have answered it sooner, but I have not been very well for the few last days. Your letter has, also, flattered me much in many points.

I am very glad you have been thinking over the relation of subsidence & the accumulation of deposits:² it has to me removed many great difficulties; please to observe that I have carefully abstained from saying that sediment is not deposited during periods of elevation, but only that it is not accumulated to sufficient thickness to withstand subsequent beach action: on both coasts of S. America, the amount of sediment deposited, worn away & redeposited oftentimes must have been enormous, but still there have been no wide formations produced: just read my discussion (p. 135 of my S. American Book) again with this in your mind.—³

I never thought of your difficulty (ie in relation to this discussion) of where was the land whence the 3 miles of S. Wales strata were derived?⁴ Do you not think that it may be explained, by a form of elevation, which I have always suspected to have been very common (& indeed had once intended getting all facts together). viz thus

The frequency of a deep ocean close to a rising continent, bordered with mountains, seems to indicate these opposite movements of rising & sinking close together: this w^d. easily explain the S. Wales & Eocene cases.— I will only add that I sh^d think there w^d be a little more sediment produced during subsidence than during elevation, from the resulting outline of coast after long period of rise.— There are many points in my vol^s. which I sh^d. have liked to have discussed with you, but I will not plague you: I sh^d like to hear whether you think there is anything in my conjecture on Craters of Elevation;⁵ I cannot possibly believe that St. Jago or Mauritius are the basal fragments of ordinary volcanos; I w^d sooner even admit E. de Beaumont’s view than that; much as I w^d sooner in my own mind in all cases follow you.— Just look at p. 232 in my S. America for trifling point,⁶ which however, I remember, to this day releived my mind of a considerable difficulty.—

I remember being struck with your discussion on the Missisippi beds⁷ in relation to Pampas, but I sh^d. wish to read them over again, I have, however, relent your work to M^rs Rich,⁸ who, like all whom I have met, have been much interested by it.— I will stop about my own geology.— But I see I must mention, that Scroope did suggest (& I have alluded to him, p. 118 but without distinct reference & I fear not sufficiently, though I utterly forget what he wrote⁹ ) the separation of basalt & trachyte, but he does not appear to have thought about the crystals which I believe to be the Keystone of the phenomenon: I cannot but think this separation of the molten elements has played a great part in the metamorphic rocks: how else c^d the basaltic dykes come in great granitic districts such as those of Brazil?— What a wonderful book for labour is D’. Archiac!¹⁰

We are going on as usual: Emma desires her kind love to Lady Lyell: she boldly means to come to Birmingham with me & very glad she is that Lady Lyell will be there:¹¹ two of our children have had a tedious slow fever.—¹² I go on with my aqueous processes & very steadily but slowly gain health & strength. Against all rules¹³ I dined at Chevening with L^d. Mahon,¹⁴ who did me the gr^t. honour of calling on me, & how he heard of me, I can’t guess— I was charmed with Lady Mahon, & anyone might have been proud at the praises of agreeableness which came from her beautiful lips with respect to you.— I liked old L^d. Stanhope¹⁵ very much; though he abused geology & zoology heartily— “To suppose that the omnipotent God made a world, found it a failure, & broke it up & then made it again & again broke it up, as the geologists say, is all fiddle faddle”.— Describing species of birds & shells &c is all “fiddle faddle”.¹⁶ But yet I somehow liked him better than L^d Mahon.—

I am heartily glad we shall meet at Birmingham, as I trust we shall if my health will but keep up.— I work now every day at the Cirripedia for 2$\frac{1}{2}$ hours & so get on a little but very slowly.— I sometimes after being a whole week employed & having described, perhaps only 2 species agree mentally with L^d. Stanhope that it is all fiddle-faddle: however the other day I got the curious case of a unisexual, instead of hermaphrodite, cirripede, in which the female had the common cirripedial character, & in two of the valves of her shell had two little pockets, in each of which she kept a little husband;¹⁷ I do not know of any other case where a female invariably has two husbands.— I have one still odder fact, common to several species, namely that though they are hermaphrodite, they have small additional or as I shall call them Complemental males:¹⁸ one specimen itself hermaphrodite had no less than seven of these complemental males attached to it. Truly the schemes & wonders of nature are illimitable.— But I am running on as badly about my Cirripedia as about Geology: it makes me groan to think that probably, I shall never again have the exquisite pleasure of making out some new district,—of evoking geological light out of some troubled, dark region.— So I must make the best of my Cirripedia.—

Remember me most kindly to M^r & M^rs Bunbury.— I am sorry to hear how weak your Father is—¹⁹ | Yours most sincerely | C. Darwin