46 B. A. Daly — Mechanics of Igneous Intrusion. 



two hundred degrees above its melting point* — the separation 

 of its acid-alkaline and ferromagnesian elements by gravity is 

 further perfected. Morozewicz has given a telling experi- 

 mental demonstration of the process. He melted two pounds 

 of granite and left the superheated melt in a hot part of an 

 active glass-furnace for five days. It was * then cooled to a 

 glass. At the end of the time he found that the lower part 

 of the melt carried 59'20 per cent of silica, the upper part 

 73*65 per cent ; the original granite showed 68*9 per cent.f 

 An actual case of repeated differentiation of the kind seems 

 to be represented in the Okanagan Mountain range, where, one 

 after another, the Osoyoos-Remmel, Similkameen and Cathe- 

 dral batholiths have been intruded, and clearly in the order of 

 decreasing specific gravity of the rocks. :{: 



It is, however, to be expected, on the stoping hypothesis, 

 that the primary basaltic magma may close an entire petro- 

 genic cycle, since the latest phase of a batholith, after crystal- 

 lizing, may be fissured and injected with a small volume of 

 the substratum. The common occurrence of diabase or pro- 

 phyrite dikes in granite may be thus explained. 



Origin of magmatic water and gases. — Finally, the stoping 

 hypothesis implies that, since post-Archean batholiths have 

 generally replaced large volumes of sediments, the volatile 

 matter which is normally trapped within a geosynclinal prism 

 should form an important part of the secondary magma. 



An approximate idea of the amount of volatile matter in 

 the average argillite§, sandstone and limestone of the world is 

 readily obtained. For this purpose we may use Clarke's com- 

 posite analyses of 843 limestones, 624 sandstones, 27 Mesozoic 

 and Cenozoic shales and of 51 Paleozoic shales, together with 

 38 analyses of various argillites from different parts of the 

 United States. || From these analyses the writer has deter- 

 mined, for the argillites, the average amount of water below 

 110° C. (H 2 0-), water above 110° C. (H 3 0+), carbon dioxide, 

 carbon (and carbonaceous matter), and sulphur (in S0 8 ). 

 These averages represent, respectively, 116, 116, 106, 78 and 

 78 typical specimens of argillite from as many localities. The 

 averages for sandstone and limestone have been taken directly 

 from Clarke's work and all three sets are noted in the follow- 

 ing table : 



An inspection of the table makes it clear that the total of 

 the " combined water", carbon dioxide, carbon and carbona- 

 ceous matter, sulphur and chlorine in the stratified rocks 



* F. Loewinson-Lessing, op. cit., p. 380. 



f Op. cit., p. 2(32. Cf. C. Doelter, Pedogenesis, Braunschweig, p. 79, 1906. 



% Bull. Geol. Soc. America, xvii, p. 329, 1906. 



§ The term "argillite" here includes both shales and slates. 



|| F. W. Clarke, Bull. No. 228, U. S. Geol. Surv., p. 20 ff., 1904. 



