562 T. E. Sti'ut/iers— Granite. 



facts, it may now be ranked among the ingenious speculations 

 which, in early times, preceded the advance of science to such a 

 degree, but hypotheses, however ingenious, have little prospect of 

 being accepted now-a-days, unless based on incontrovertible facts. 



It must be admitted, however, that although the first principles of 

 the Wernerian and Huttonian 'theories' of the earth are unsatis- 

 factory, the hypotheses of these propounders of the two opposite 

 geological doctrines (we cannot consider thera entitled to rank as 

 tlieories) have been extremely useful in giving an impetus to the 

 accumulation of knowledge and in the search for truth ; whilst in 

 the course of their investigations both Werner and Hutton described 

 and explained many geological phenomena, and thus rendered 

 important aid to future explorers, who again did good service to 

 science, even in the correcting of such errors as may have been 

 made by the original observers. 



Stratified rocks must originally have been derived from unstrati- 

 fied rocks ; and the inorganic constituents of the former may be 

 traced back to granite, while the direct relation of that rock to 

 gneiss, quartzite, mica-schist, and clay-slate, intimately associated 

 with it, is so evident as to leave no room for doubt. It may also be 

 observed that erupted rocks, whether volcanic, or trappean, have 

 apparently been derived from granite, for in common with them it 

 consists mainly of silica, alumina, potash, soda, lime, magnesia, and 

 iron in varying proportions; and according to Beete Jukes, " if we 

 could follow any actual lava stream to its source in the bowels of 

 the earth, we should in all probability be able to mark in its course 

 every gradation from cinder or pumice to actual granite." 



The hydrothermal conditions under which granite was formed 

 are generally acknowledged, but these conditions were peculiar to 

 a particular period of the world's history, when a sea of a high 

 temperature overspread its entire surface before any dry land had 

 appeared. The first terrestrial surfaces would necessarily consist 

 of portions of the sea bottom elevated by volcanic agency after it 

 had cooled, consolidated, and contracted. Had no such upheaval 

 taken place there would have been a foundation laid, but there could 

 have been no superstructure of strata. We may also remark that 

 from the circumstance that gi-anite frequently assumes a bedded 

 form, and in many instances contains fragments of the older stratified 

 rocks evidently enveloped when it was in a molten state, and also 

 that it has been observed in junction with them, it would appear 

 that outbursts of the newer granite must have taken place for some 

 time after the elevation of the first dry land, from which the 

 sedimentary rocks had been derived. 



The structure of granite indicates pressure during consolidation ; 

 but in accounting for this it is not necessary to adopt the current 

 theory of its origin, for the sea, the depth of which we may estimate 

 at two miles, would exert a pressure of several hundred atmospheres. 

 'J'he commonly adopted theory of the origin of granite appears to 

 be based upon the Huttonian h^'pothesis that "it was elevated from 

 the ocean, raising up the strata before it." This is partly true, for 



