1864.] T. STERRY HUNT ON LITHOLOGY. 17 



opinion untenable. It is not here the place to discuss the more 

 or less ingenious speculations of Phillips, Durocher, and Bunsen 

 as to the constitution of this supposed fluid centre, nor the more 

 elaborate hypothesis of Sartorius von Waltershausen as to the 

 composition and arrangement of the matters in this imaginary 

 reservoir of plutonic rocks. The immense variety presented in 

 the composition of eruptive masses presents a strong argument 

 against the notion that they are derived, as these writers 

 have supposed, from two or more zones of molten matter, 

 differing in composition and density, and lying everywhere 

 beneath the solid crust of the earth ; which, in opposition to the 

 views of many modern mathematicians and physicists, the school 

 of geologists just referred to regard as a shell of very limited 

 thickness. 



The view which I adopt is one the merit of which belongs, 

 I believe, to Christian Keferstein, who, in his Naturgescliichte des 

 Erdkorpers, published in 1834, maintained that all the unstratified 

 rocks, from granite to lava, are products of the transformation 

 of sedimentary strata, in part very recent ; and that there is no 

 well-defined line to be drawn between neptunian and volcanic rocks, 

 since they pass into each other (vol. i, p. 109.) This view was 

 subsequently, and it would seem, independently brought forward 

 in 1836 by Sir John Herschel, who sought to explain the origin of 

 metamorphism and of volcanic phenomena by the action of the 

 internal heat of the earth upon deeply buried sediments impreg- 

 nated with water. (Proc. Geol. Soc. of London, vol. ii, pp. 548, 596.) 

 See also my papers in the Canadian Journal, 1858, p. 206; Quar. 

 Jour. Geol. Soc. 1859, p. 488 ; Can. Naturalist, Dec. 1859; and 

 Silliman's Journal [2], vol. xxx, p. 135. 



The presence of water in igneous rocks, and the part which it may 

 play in giving liquidity to all volcanic and plutonic rocks, was 

 insisted upon by Poulett Scrope, so long ago as 1824, in his Con- 

 siderations on Volcanoes. (See also Quar. Jour. Geol. Soc. London, 

 xii, 341,) This view has since been ably supported by Scheerer in 

 his discussion with Durocher. (Bui. Soc. Geol. France [2], iv, 468, 

 1018 ; vi, 644; vii, 276 ; viii, 500.) See also Elie de Beaumont, 

 ibid., iv, 1312. Theadmirable investigations of Sorby on the micro- 

 scopic structure of crystals (Quar. Jour. Geol. Soc, xiv, 453) 

 have since demonstrated that water has intervened in the crystalli- 

 zation of almost all plutonic rocks. He has shown that the quartz 



Vol. I. B No. 1. 



