CHEMISTRY OF THE EARTH. 199 



line to be drawn between neptunian and volcanic rocks, since they pass 

 into each other. Volcanic phenomena, according to him, have their 

 origin, not in an igneous fluid center, nor in. an oxidizing metallic 

 nucleus, (Davy, Daubeny,) but in known sedimentary formations, where 

 they are the result of a peculiar kind of fermentation, Avhich crystallizes 

 and arranges in new forms the elements of the sedimentary strata, with 

 an evolution of heat as a result of the chemical process, [Xaiurgeschichte, 

 vol. i, 1). 109 ; also Bulletin de la 8ocict6 Geoloyique cle France, [1], vol. 

 vii, p. 107.) In commenting upon these views, {Ameyican Journal of 

 Science, July, 1800,) I have remarked that, by ignoring the incandescent 

 nucleus as a source of heat, Keferstein has excluded the true exciting- 

 cause of the chemical changes which take place in the buried sediments. 

 The notion of a subterranean combustion or fermentation, as a source of 

 heat, is to be rejected as irrational. 



§ 37. A view identical with that of Keferstein, as to the seat of vol- 

 canic phenomena, was soon after put forth by Sir John Herschel, in a 

 letter to Sir Charles Lyell, in 183G, {Proceedings of the Geological Society 

 of London, ii, 518.) Starting from the suggestion of Serope and Babbage, 

 that the isothermal horizons in the earth's crust must rise as a conse- 

 quence of the accumulation of sediments, he insisted that deeply-buried 

 strata will thus become crystallized by heat, and may eventually, with 

 their included water, be raised to the melting point, by which process 

 gases would be generated, and earthquakes and volcanic eruptions follow. 

 At the same time the mechanical disturbance of the equilibrium of pres- 

 sure, consequent upon a transfer of sediments, while the yielding surface 

 reposes on matters partly liquified, will explain the movements of eleva- 

 tion and subsidence of the earth's crust. Herschel was probably ignorant 

 of the extent to which his views had been anticipated by Keferstein ; and 

 the suggestions of the one and the other seemed to have passed unnoticed 

 by geologists until, in March, 1858, I reproduced them in a paper read 

 before the Canadian Institute, (Toronto.) being at that time acquainted 

 with Herschel's letter, but not having met with the writings of Kefer- 

 stein. I there considered the reactions which would take place under 

 the influence of a high temperature in sediments permeated with water, 

 and containing, besides silicious and aluminous matters, carbonates, sul- 

 phates, chlorides, and carbonaceous substances. From these, it was 

 shown, might be produced all the gaseous emanations of volcanic dis- 

 tricts, while from aqueo-igneous fusion of the various admixtures might 

 result the great variety of eruptive rocks. To quote the words of my 

 paper just referred to: "We conceive that the earth's solid crust of 

 anhydrous and primitive igneous rock is everywhere deeply concealed 

 beneath its own ruins, which form a great mass of sedimentary strata, 

 l)ermeated by water. As heat from beneath invades these sediments, it 

 produces in them that change which constitutes normal metamorjihism. 

 These rocks, at a sufflcient depth, are necessarily in a state of igneo- 

 aqueous fusion ; and in the event of fracture in the overlying strata, 

 may rise among them, taking the form of eruptive rocks. When the 

 nature of the sediments is such as generate great amounts of elastic 

 fluids by their fusion, earthquakes and volcanic eruptions may result, 

 and these — other things being equal — will be most likely to occur under 

 the more recent formations.'' {Canadian Journal, Mav, 1858, vol. iii, p. 

 207.) 



§ 38. The same views are insisted ujjon in a i:)ai)er " On some points in 

 Chemical Geology." (Quarterly Journal of the Geological Society, Lon- 

 don, November, 1859, vol. xv, page 591,) and have since been repeatedly 

 put forward by me, with further explanations as to what I have designated 



