To Charles Lyell [November–December 1851]1
– p. 36.2 —pozzolana I actually found bolts of iron embedded with conglomerate at the C. Verds. p. 21 Volcanic Islds.3 p. 40 is it correct that wood in the ground (not peat-bog) lasts longer than in water— this sounds very strange to me.—4 p. 66. The opening sentence makes me groan, viz your saying denudation is owing to “running water”, for breakers cannot be called running water— you seem to preclude beach or tidal action— I know it is only in expression.—5 p. 81. ought you not to add earthquakes to causes of formation of alluvium.—6 It strikes me that a very little more ought to be said about sand-dunes—coral-sand—Laterite Kunkaer.7 p. 85. “In some cases, the alluvium in which” &c— Surely is not the tendency of all researches to show that in most cases, the alluvium or superficial drift, (even so-called vegetable black mould in S. America) is of marine origin.—8
Ought not a short account to be given of the Aralo-Caspian deposits of Murchison?9 p. 88. Even in shortest account of Glen Roy, notice ought to be taken of the intermediate shelf, of Tom Brahn which so clearly proves that the roads or beaches are not at all necessarily conterminous with the old expanses of water.—10 p. 113 At Coquimbo there is another case of (1) a bed with all recent shells in same proportion as on beach— (2) of a bed with recent shells, but in different proportion (3) of nearly all extinct species.11 p. 208. I think the S. American Tertiaries deserve a paragraph, if merely from area; where else can you travel uninterruptedly for at least 42o Lat: or 1620 over Tertiaries, without a sign of disturbance, fault or flexure: for 600 miles the formation contains only extinct shells— How grand is the superimposed contemporaneous basaltic lava, which has extended in a sheet 100 miles from source, & at end is 130 ft thick. In Chile it appears to me very interesting to find old, apparently Eocene, tertiaries, not indicating a hotter climate than that of Latitude in which they occur.—12 p. 217. The coral-mud is actually seen to be transported out of the opening, discoloring the sea, from the Maldivas atolls.—13 p. 228 “Cypris, an animal allied to the Crustacea”— you might as well say a seal or whale was allied to the mammalia.14 p. 282. Those who do not know you to be an Entomologist, would think fromap-position of words, that you fancied that “Carabus” was a “wood-eater”.—15 p. 273. I wish you had grappled with d’orbigny & others who speak of every species as distinct in the stages of the Chalk & Oolites16 p. 301 The Permian Chapter strikes me as rather short: one wants to hear a bit more about Russia17 p. 362. I will always protest against your distinction of Recent & Post-pliocence.—18 I declare, I think it wd be a good thing if your most useful Table had been printed at the beginning as well as at the end of the Chapters describing special Formations.19 p. 376. In the list, Palagonite of Bunsen ought to be introduced20 ramme
If you intend your Manual to serve as an Introduction to a student going to a Volcanic district & as a guide to him what to observe, the Chapters strike me as very scanty & incomplete: (by incomplete I do not mean to say a word against all that is, which strikes me as excellent, only I think more is wanted.) surely particulars about “fluidity of lavas” inclination of streams—preexisting crystals—details on nature of amygdaloids—inclined strata within craters—obsidian—dolerite—Bombs—vaulted streams—ejected granitic fragments—tuff which has flowed as mud—blown up masses—subsided masses—state of surface of lava—effects of hot lava on underlying matter. &c &c.21
In Cleavage discussion, it appears to me to be the gravest omission to leave out all allusion to Dan. Sharpes facts about change in shape in shells, with Mr Hopkins discussion on subject, which latter I presume you do not disbelieve in—22 I cannot doubt that Sharpes facts are most important with respect to origin of cleavage— Do you bring out prominently enough, the vast areas with uniform strike, but varying dip of cleavage;23 its parallelism to ranges of mountains & areas of elevation?.— I presume you do not believe in the Fan-like structure as held by Sharpe, & as stated to be case with foliated rocks by Studer.24
With respect to foliated rocks, I wish you had read my few pages on subject which I see you have not; I do not at all suppose that all gneiss has actually flowed: the analogy from the obsidian layers is not by any means my chief argument.— In fact you seem at end of discussion willing to grant almost all I want, when you state that cleavage planes might be converted into the layers of various mineralscom-posing the metamorphic schists; for then these wd not be due to deposition.—25 p. 468. I am astonished at your comparing the undulations in these schists to ripple-marks: is not d’Aubuissons explanation of expansion by heat far more probable?—26 Does it not appear odd to you that the outline & diverse composition of pebbles not being preserved, when, on your view, millions of layers of sediment have been perfectly preserved?
You know that even Sedgwick admits a grain in Plutonic rocks; & such I most certainly have seen, where it was very difficult to make any clear distinction from gneiss.— But enough, & too much you will say.— I will only add that the fact, which I clearly saw in T. del Fuego, that in simple clay-slate there were slight mineralogical differences in the cleavage laminæ, seem to me important.27 p. 472.— The passage quoted from me had better be struck out: I told you so before, but I presume you forgot.— I am fearful I may have blundered.—28
In your capital Mineral vein Chapter, might you not give some facts of the wide diffusion of the metals; some chemists have, I think, detected Copper in sea-water.— As illustrating the adhesion of metal to plutonic & hot volcanic districts; would it not be worth contrasting the entire ignorance of all metals in the inhabitants of the Pacific islands, with the aborigins of S. America.—29
P.S. I earnestly beg you to read just 5 pages in my vol. on S. America, p. 162 et Seq. on Foliation, for I am interested on the subject.—30
Detailed critique of CL’s A manual of elementary geology [3d ed. (1851), used in editing 4th ed. (1852)].
Please cite as
Darwin Correspondence Project, “Letter no. 1384,” accessed on 25 May 2016, http://www.darwinproject.ac.uk/DCP-LETT-1384