Stockdale: Stylolites 



47 



Effect of Temperature upon the Solution of Solids in Liquids 



Altlio the solvent action of water, especially if charged 

 with carbon dioxide, is marked at ordinary or even low tem- 

 peratures, there is no doubt that the action is increased by 

 heat. That, as a rule, solids are more soluble in warm than in 

 cold solvents is an established fact. 



Effect of Pressure upon the Solution of Solids in Liquids 



That the effect of pressure must be recognized as impor- 

 tant in increasing the solubility of certain solids in 

 liquids, is a factor of special significance in considering the 

 origin of stylolites. From this principle it follows that, at the 

 places of increased pressure, increased solution takes place. 

 Van Hise states that 



In the common case in which the volume of the solution is less than 

 that of the solvent and solid, pressure increases solubility; for in that 

 case solution tends to bring the molecules together and works in con- 

 junction with the pressure. . . . It is well known that the solubility 

 of calcium carbonate is increased by pressure (Van Hise, 1904, pp. 77-78). 



This principle has also been recognized and emphasized by 

 Geikie (1903, pp. 411, 419). It has been thoroly estabHshed 

 by E. Rieke, Sorby, and others, and experimentally confirmed 

 by F. Becke and Daubree. Upon this principle is based the 

 theory of the origin of the solution type of impressions in 

 pebbles (see p. 18). Here is a case of a mass of pebbles in a 

 conglomerate where, of course, the pressure exerted upon 

 each other is at the point of contact, and where the solution 

 of the one takes place at the point of contact with the other. 



Result of Supersaturation of a Solution 



Since increased pressure or temperature, or both, may re- 

 sult in a supernormal amount of a solid being dissolved by a 

 solvent, a decrease in the pressure or temperature may give 

 rise to a supersaturated solution, and a consequent crystalliz- 

 ing out of the excess solute. Release of pressure gives a 

 similar result in the solution of gases in liquids. For example, 

 water under pressure is capable of dissolving an excess of 

 carbon dioxide, and consequently of carrying an excess of 

 mineral matter in solution. Release of pressure upon the 

 solvent effects an escape of some of the carbon dioxide and a 



