664 A TREATISE ON METAMORPHISM. 



and the rock particles molecular attraction is not so important as between 

 rock particles and a liquid; therefore, so far as the water is gaseous, there 

 are probably no strongly adherent films in the openings. The gas, as 

 already explained, is very dense; gas is very mobile; therefore, so far as 

 the water is in the form of gas, it would be likely to very effectively make 

 its way from places of great pressure to places of less pressure. With a 

 given amount of water per unit volume the water gas would move from 

 places of higher temperature toward places of lower temperature, for with 

 a given amount of gas occupying the same volume, the higher the temper- 

 ature the higher the pressure. 



As to what extent the water is in the form of liquid and to what extent 

 it is in the form of gas we know so little that n~ attempt is made to discuss 

 the movement of the two separately. The statement below is true for 

 both aqueous solutions and gaseous solutions of the zone of anamorphism- 

 Where the term water is used in the succeeding paragraphs there is no 

 implication as to which state the compound is in. 



Disregarding the possible transmission of water through the inter- 

 molecular opening's, all of the subcapillary and capillary openings would be 

 taken advantage of at every favorable opportunity, and favorable oppor- 

 tunities would be furnished at times of orogenic movement. In the zone of 

 anamorphism during earth movements the mineral particles either are 

 broken and move differentially with reference to one another, or else are 

 recrystallized, or the two combined. In any case there is a constant read- 

 justment of the rock material by which the positions of the minute openings 

 are constantly chang-ed. Where the movements are rapid, supercapillary 

 openings temporarily extend downward from the belt of cementation. (See 

 pp. 658-659.) During orogenic movement the pressures vary greatly 

 from place to place; indeed, at the same place they vary from moment to 

 moment. This results in very variable pressure upon the water solutions 

 within short distances. Therefore, during orogenic movements, when the 

 rock material itself is in motion, the water is in most active movement. 

 The activity of the water in connection with deformation would be further 

 likely to be promoted by the fact that locally the movements would raise 

 the temperature above the critical point if it were not so already, and thus 

 the water would be in the form of water gas, and hence have the high 

 mobility of that form. 



