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Indiana University Studies 



assumption that the clays are residual, in view of determin- 

 ing whether or not they fulfil the requirements of a solution 

 residue of the limestone in which they are found. 



In selecting material for the analyses one must take pre- 

 cautions that the samples are properly related — the limestone 

 must be the nearest possible to that from which the clay was 

 supposedly derived. Thus, the limestone directly above an 

 upward-penetrating stylolite would probably be a fair test 

 of the stone from which the clay cap was derived, unless there 

 had been also some solution of the column itself. The lime- 

 stone of the adjacent downward-penetrating stylolite would 

 also furnish a fair test of the material which had been re- 

 moved next to it. Since the clays are so thin, difficulty is 

 experienced in collecting material which is entirely free from 

 particles of the adjacent country rock. At the best, one can 

 hardly expect to procure a sample which would give an error- 

 less analysis of the missing dissolved limestone. The follow- 

 ing analyses, however, show surprising results: 



