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Indiana University Studies 



overlying, parallel seams are so close together as to penetrate, 

 or even partially eradicate, one another (see p. 64). 



The stylolite-partings of the Salem limestone attract much 

 popular attention because they necessitate a considerable 

 amount of waste stone which is not generally utilized for 

 commercial purposes (see Fig. 18) . 



PHYSICO-CHEMICAL BASIS OF THE SOLUTION THEORY 



Statement of the Theory 



That the writer's investigations of stylolitic phenomena 

 revealed conclusive evidence in support of the solution theory, 

 and in direct opposition to the pressure theory, has already 

 been stated. Briefly, the writer wishes to present the theory 

 as follows: Stylolitic phenomena result from the differential 

 chemical solution of hardened rock, under pressure, on the two - 

 sides of a bedding plane, lamination plane, or crevice, the un- 

 dissolved portions of the one side fitting into the dissolved-out 

 parts of the opposite, the intei-fitting taking place slowly and 

 gradually as solution continues. Stylolites are limited to car- 

 bonate rocks. The explanation of their origin is taken up in 

 detail on page 49. A discussion of the solution theory first 

 necessitates the consideration of a few physico-chemical 

 factors. 



Effect of Carbon Dioxide upon Solution 



Of the various constituents absorbed by water, which are 

 especially effective in chemical changes in rocks, carbon dioxide 

 is one of the most important. That nearly all minerals are 

 more or less attacked even by pure water, and that their solu- 

 bility is markedly increased in water containing dissolved car- 

 bon dioxide (carbonic acid), are well-known facts which need 

 no further discussion. 



Effect of Pressure upon the Sohition of Gases in Liquids 



From the law of Henry it follows that increase of pressure 

 upon a liquid increases the weight of gas going into solution, 

 the increase being proportional to the amount of pressure. 

 Thus, an increase in pressure results in a proportional increase 

 in the amount of carbon dioxide which water dissolves, which 

 in turn increases the dissolving strength of carbonic acid upon 

 the minerals attacked. 



