My dear Darwin

… What a change in 14 years—all the neolithic & paleolithic period, & your “Origin” since my 9^th Edition!¹ I shall be very curious to read what you will say on Man & his Races. It was not a theme to be dismissed by you in a chapter of your present work.² You must have so much to say & gainsay. If you had treated of Man in your present book, I think I should have been disposed to keep back mine, that I might start from the new goal, but as it is, I am content to declare, that any one who refuses to grant that Man must be included in the theory of Variation & Natural Selection, must give up that theory for the whole of the organic world.

Have you seen Rüttemayer “Die Herkunft unserer Thierwelt”.³ I must read it. He seems to take the derivation hypothesis for granted in all his reasoning. I do not like to have to controvert Sir John Herschel, but surely his recently published doctrine of almost every active volcano being at the junction of continents & the sea, is untenable.⁴ The number of insular volcanoes rising from the deep ocean is very great, & where the ocean is from three to six miles deep, there are probably as many unknown to us, as in the less profound parts of the ocean. We should have known nothing of Madeira & the Canaries, if they had been strictly in Mid-Atlantic. Herschel’s explanation is that rivers carry down a great weight of matter from the land to the bed of the sea. The latter area is loaded while the land is relieved of pressure, then comes a crack in the solid crust along the coast line for the crust overlies the internal fluid nucleus. Up goes the light area, & down goes the heavy one, & the lava oozes out like water when ice cracks.— How does this account for the eruption which happened the other day in the deep sea in the Samoa group of islands in the Pacific.⁵ To me it seems that the absence of water is the reason why we have not inland volcanoes. They require steam, they get this first near the land, then a thousand miles or more distant from it, as in the Azores, & then probably in deeper water where we cannot witness the outburst at the surface.

But Herschel says that the waste of the continents causes the laying on of so much new solid substance over the bottom of the Pacific as to cause that bottom to be sinking (p. 12. Familiar Lectures on Scientific Subjects). Have you any where spoken of the cause of volcanoes not being far from the sea?⁶

We go to Paris in a fortnight & then to Scotland to return in Sept^r. | Ever affec^tly Y^rs | Cha Lyell