112 Lt.-Gen. 3fc3fahon — The Rape of the Chlorites. 



The heat, produced locally by the crushing and shearing of the 

 solid rock, he tell us, " often rose to the point of fusion in the shear 

 zones." What the fusion point was the author does not tell us, but 

 it is obvious that the fusion of rocks, such as those contemplated, 

 must have requii-ed a very high temperature. 



The intense heat, however, under Dr. Callaway's supposition, was 

 limited to the shear zones and was quite local. In other parts of the 

 same rock, namely those in which chlorite is now to be found, the 

 temperature could not have risen to red heat, for at a red heat, the 

 author tells us, chlorite loses its water. 



The author accounts for the escape of water from the altered 

 chlorite, by its having been driven off by heat. The " elimination " 

 of the water from the chlorite, he tells us, offers " no serious 

 difficulty." If so, the rock was, for all practical purposes, a porous 

 rock through which water could be driven by heat. 



The conditions supposed to have existed are then briefly as follows : 

 (1) The presence of centres of intense heat produced by local 

 crushing and shearing; (2) The existence of temperatures below 

 red heat in other parts of the rock ; (3) A porosity in the rock 

 suiBcient to allow water to escape from it. 



ISuch being the conditions I am at a loss to understand how the 

 heated chlorite, whilst parting with 12 per cent, of water and 16 per 

 cent, of magnesia, can have acquired 2 per cent, of alumina, 8 per 

 cent, of potash, and 11 per cent, of iron in addition to the alumina 

 and iron already jDresent in it. 



The intense heat at the local centres would surely have driven 

 away all the water from those centres to the cooler parts of the 

 rock. The dehydration of the chlorite is accounted for on that 

 supposition. This water, charged, as it probably was, with acid, 

 may have carried away with it the 16 per cent, of magnesia, but by 

 what agency was the additional alumina, potash, and iron conveyed 

 to the chlorites? The water contained in the rock must have been 

 repelled and driven away, as before stated, from the centres of heat. 

 When this water, charged with bases in solution, was moving away 

 from these centres, how could the iron, alumina, and potash in the 

 pores of the rock through which the water passed have forced their 

 way to the distressed chlorites in the face of the bombardment to 

 which they must have been exposed by the panic-stricken molecules 

 rnshino- away from the centres of disturbance? By what power was 

 the iron, alumina, and potash moved against this stream of fugitives ? 



1 doubt whether, under the conditions supposed, any chlorite 

 would have remained near the centres of heat. Chlorite is readily 

 susceptible to the action of acids ; and water, even faintly charged 

 with acids, would, at the high temperature predicated, in all proba- 

 bility have swept all the alumina, iron, and magnesia contained in 

 the chlorites out of these minerals. That the acidified water 

 should have removed 16 per cent, of magnesia and have left the 

 whole of the iron is highly improbable, for, as far as my experience 

 in experiments on minerals goes, I should say that iron is one of 

 the first bases to be removed by acid solvents. 



