28 DE. THOMAS STERRY HUNT ON THE 



§ 54. The nature and history of this primitive layer was farther discussed by the 

 author in a lecture ou " The Chemistry of the Primeval Earth," given at the Royal Insti- 

 tution in Loudon, in Jixne, ISeY.'" Therein it was said : " It is with the superficial portions 

 of the fused mineral mass of the globe that we have now to do, since there is no good 

 reason for supposing that the deeply-seated portions have intervened in any direct manner 

 in the production of the rocks which form the superficial crust. This, at the time of its 

 first solidification, presented probably an irregular diversified surface, from the result of 

 contraction of the congealing mass, which at last formed a liquid bath of no great depth, 

 surrounding the solid nucleus." It was further insisted that this material would contain 

 all of the bases in the form of silicates, and must have much resembled in composition 

 certain furnace-slags or volcanic products. Of this primary lava-like rock, it was said, 

 that it is now everywhere concealed, and is not to be confounded with the granitic 

 substratum. That granite was a secondary rock, formed through the intervention of 

 water, was then argued from the presence therein, as a constituent element, of quartz, 

 " which, so far as we know can only be generated by aqueous agencies, and at compara- 

 tively low temperatures." The metamorphic hypothesis of the origin of granite was 

 then maintained. 



In 1869, in an essay on " The Probable Seat of Volcanic Action," ^' a further inquiry 

 was made into the probable nature and condition of what had been spoken of in 1858 as 

 " the ruins of the crust of anhydrous and primitive igneous rock." This, it was now 

 said, " must by contraction in cooling have become porous and permeable, for a consider- 

 able depth, to the waters afterwards precipitated upon its surface. In this way it was pre- 

 pared alike for mechanical disintegration and for the chemical action of the acids .... 

 present in the air and the waters of the time. . . . The earth, air, and water, thus 

 made to react upon each other, constitute the first matters, from which, by mechanical and 

 chemical transformations, the whole mineral world known to us has been produced." It 

 was farther argued, from many geological phenomena, that we have evidence of the exist- 

 ence between the solid nucleus and the stratified rocks of " an interposed layer of partially 

 fluid matter, which is not, however, a still unsolidified portion of the once liquid globe, 

 but consists of the outer part of the congealed primitive mass, disintegrated and modified 

 by chemical and mechanical agencies, impregnated with water, and in a state of igneo- 

 aqueous fusion." 



§ 55. Although in 1858 I had, as already shown, sought to give a more rational basis 

 to the metamorphic hypothesis of the origin of crystalline rocks, the traditions of which, 

 as expounded by Lyell, weighed so heavily on the geologists of the time, other considera- 

 tions soon afterwards led me to seek in another direction for the solution of the problem. 

 The examination of the mineral silicates deposited during the evaporation of many natural 

 waters, that of the Ottawa river among others, and the study which 1 had made of the 

 hydrous magnesian silicate found in the tertiary strata of the Paris basin, induced me, as 

 early as 1860, to inquire "to what extent rocks composed of calcareous and magnesian 

 silicates may be directly formed in the moist way ;" and again, in the same year, to declare 



'" Proceedings of the Eoyal Institution, and also Chemical and Geological Essays, pp. 35-45. 

 ^^ Geological Magazine for June, 1869, and Amer. Jour. Science, for July, 1870 (vol. i., p. 21.) See also Qiemical 

 and Geological Essays, pp. 59-67. 



