S tockdale : StyloUtes 



67 



the rock had become consoHdated, or was responsible for the 

 consoKdation. That the pressure theory fails to explain such 

 an occurrence of stylolites is evident. 



The pressure theory also fails to explain the origin of 

 stylolite-seams which cut across the stratification at various 

 angles (see Fig. 17). If adherents of the pressure theory 

 would have the seam developed along an angular crevice, it 

 would fall upon them to explain the origin and existence of 

 such a crack in plastic rock. Equally difficult would it be to 

 explain the occurrence of a clay layer along such a crevice 

 (see p. 86). 



2. Evidence that the Clay Partings Are the Solution Residue 

 of the Dissolved Limestone 



The general assumption of most investigators of stylolitic 

 phenomena, with the exception of the exponents of the solu- 

 tion theory, is that the ever-present clay partings of stylolite- 

 seams represent original, once-continuous, thin layers of clay 

 material laid down in the seas with the lime sediments. The 

 solution theory holds that the clays are the residue of the dis- 

 solved rock, altho advocates of the theory, however, have 

 never given conclusive proof of this. The writer wishes to 

 present several lines of evidence showing that the clays are 

 a solution residue. 



Chemical Relations between the Clay Caps and the 

 Associated Limestone. No investigator has attempted an 

 analysis of the ever-present clays of stylolites to show the 

 chemical relations between them and the associated limestone 

 (or dolomite or marble) . If the clay caps are the solution 

 residue of the dissolved limestone, one should expect a definite 

 relationship between their chemical constituents and those of 

 the limestone from which they were derived. The clay should 

 consist, in the main, of the least soluble components of the 

 parent limestone, with probably a subordinate amount of the 

 soluble substances which have not yet been completely dis- 

 solved; since, in the solution of limestone, only the calcium 

 carbonate is removed in appreciable quantities. The clay, if 

 a solution residue, should be nothing more than a concentra- 

 tion of the less soluble constituents of the rock from which 

 it was derived. It should contain these substances in a pro- 

 portion dependent primarily upon the amount dissolved and 

 carried away during the weathering of the parent rock. 



