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Indiana University Studies 



deepening of the interpenetrating parts, {h) a decrease in the 

 pressure and consequent decrease in the solution of the sides 

 of the undulations, and (c) a final development of vertical 

 columns, with practically a complete concentration of the 

 pressure and consequent solution at the ends. The sides oi 

 the columns, being free from pressure, usually are unattacked 

 by solution. Continued solution at the ends results in a fur- 

 ther deepening and lengthening of the interpenetrating col- 

 umns. Striation of the side-surfaces results from the slow 

 movement of the columns past one another. The non-soluble 

 constituents of the dissolved rock come to rest as a clay resi- 

 due at the end of each column, and serve as a further pro- 

 tection from solution of the resistant part. Increase in the 

 length of the stylolites results in a proportional thickening 

 of the residual clay. The length of the columns serves as a 

 fair measure of the amount of solution which has taken place, 

 providing the ends of the columns themselves have not been 

 subjected to solution. On the sides of the stylolites, which 

 are free from pressure and practically unattacked by solu- 

 tion, are often found deposits of mineral matter precipitated 

 there from the supersaturated solvent resulting from the in- 

 creased pressure and amount of solution opposite the ends. 

 Such coatings of mineral matter are often slickensided as a 

 result of further growth and interpenetration of the columns. 

 The length of the stylolites depends upon three principal 

 factors: («) the length of time solution has gone on, {h) the 

 solubility of the stone, and (c) whether or not solution has 

 attacked the ends of the stylolites. 



Thus it is seen that the principal factors in the develop- 

 ment of stylolites are: (a) the presence of a crevice in the 

 rock which permits a concentration of carbonated water; 

 (h) the fact that carbonate rocks (limestones, dolomites, and 

 marbles) exhibit a differential solubility; and (c) the physico- 

 chemical principle that an increase in pressure effects an 

 increase in the solubility of a solid, as sho^vn by Rieke, Sorby, 

 Geikie, Van Hise, and others, and experimentally confirmed 

 by Becke and Daubree. 



Wagner (1913, pp. 122-123) stressed the point, from the 

 law of Henry, that an increase in pressure upon the solvent 

 at the ends of the columns would permit an increase in the 

 amount of carbon dioxide dissolved, which in turn would 

 increase the amount of solution at these places. Reis pointed 



