86 T. S. Hunt on Granitic Bocks. 



nor Virlet d'Aout, who supported Ms views, however [ibid., iv, 

 p. 493) extended them, to feldspathic veins, though Daubree, 

 at an earlier date, had described certain granitic veins in Scan- 

 dinavia as having been formed by secretion rather than hy igne- 

 ous injection, as maintained by Durocher. 



§9. EHe de Beaumont, starting from the hypothesis of a 

 cooling liquid globe, imagined " a bath of molten matter on 

 the surface of which the first granites crystal lized." From 

 the ruins of these were formed the first sedimentary dejx.v -. 

 but directly beneath were other granitic masses, which 1 it- 

 fixed immediately afterward. "Some parts of these lu; 

 coagulated from the commencement of the cooling pror:-, 

 but not completely solidified, were then erupted through tue 

 sedimentary deposits " just mentioned. " In these jets of pasty 

 matter " were contained many of the rarer elements of the 

 granitic magma, which were thus concentrated in the outeraiost 

 portions of the granitic crust, and in the ramifications fomed 

 by these portions in the masses through which they were forced 

 by the eruptive agents. Those portions of the granitic masses, 

 and their ramifications, in which these rarer elements are con- 

 centrated, are distinguished from the rest of the masses alike 

 by their exterior position and their peculiar structure. They 

 are often coarse-grained and include the pegmatites, tourmaline- 

 granites, and veins carrying cassiterite and columbite, often 

 abounding in quartz. These mineral products are to be re- 

 garded as emanations from the granite, and are described as a 

 granitic aura, constituting what Humboldt has called the 

 penumbra of the granite. {Bull. Soc. Geol. de France, (2) iv, 12iy- 

 See particularly pages 1295, 1321 and 1323). , 



§ 10. While Fournet, Durocher and Riviere conceived the 

 granitic magma to have been purely anhydrous, and in a state 

 of simple igneous fusion, Elie de "Beaumont maintained witti 

 Poulett-Scrope and Scheerer that water had in all cases inter- 

 vened, and that a few hundredths of water might at low rea 

 heat have given rise to the condition of imperfect liquidity 

 which he imagined for the material of the injected granites. 

 The coarsely crystalline granitic veins were according to him 

 veins of injection, and he speaks of them as examples id 

 which " the phenomena essential to the formation of granw 

 had been manifested with the greatest intensity." ThegraQij'. 

 emanations, which are supposed to have furnished the m^*^^ ^ 

 of these veins, appear to be regarded by him as the result o 

 process of eliquation from the congealing granitic mass. 

 Beaumont is careful to distinguish between them and m 

 emanations which are dissolved in mineral waters or ^^^^^ ^ 

 as volcanic vapors, (page 1324). To the agency of such wat 

 he ascribes the formation of concretionary veins, which are g _^ 

 rally characterized by their symmetrically banded struct 



