VI.] THE PROBABLE SEAT OF VOLCANIC ACTION. 63 



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 repro- 

 duced 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 Keferstein. I there 

 considered the reaction which would take place under the in- 

 fluence of a high temperature in sediments permeated with 

 water, and containing, besides silicious and aluminous matters, 

 carbonates, sulphates, chlorides and carbonaceous substances. 

 From these, it was shown, might be produced all the gaseous 

 emanations of volcanic districts, 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 anhy- 

 drous and primitive igneous rock is everywhere deeply concealed 

 beneath its own ruins, which form a great mass of sediment- 

 ary strata, permeated by water. As heat from beneath invades 

 these sediments, it produces in them that change which con- 

 stitutes normal metamorphism. These rocks, at a sufficient 

 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 to 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." (Cana- 

 dian Journal, May, 1858, Vol. III. p. 207 ; and ante, page 9.) 

 The same views are insisted upon in a paper On some 

 Points in Chemical Geology (Quar. Jour. Geol. Soc., London, 

 Nov., 1859, Vol. XV. p. 594), and have since been repeatedly 

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

 have designated above, the ruins of the crust of anhydrous and 

 primitive igneous rock. This, it is conceived, must, by contrac- 

 tion in cooling, have become porous and permeable, for a con- 

 siderable depth, to the waters afterwards precipitated upon its 

 surface. In this way it was prepared alike for mechanical dis- 



