Stockdale: StyloUtes 



61 



were formed after the hardening of the rock, since the altera- 

 tion of the buff stone from the blue is in itself (according to 

 the theory) a feature which occurred since the consolidation 

 of the rock. Observations of the above nature are not uncom- 

 mon in the Salem limestone. It has been suggested, how- 

 ever, that the above-described color changes of alternating 

 columns could have occurred since the development of the 

 stylolites, altho evidence appears to be against it. 



Fig. 27. — Semi-diagrammatic sketch of stylolites in the Salem 

 limestone, showing blue (shaded) portions of the lower 

 stratum penetrated by buff columns of the upper layer. 

 One-third natural size. 



Relation of Stylolites to Fossils. Careful observa- 

 tions of Indiana stylolites show the presence of fossil caps 

 to be an exception. This fact alone precludes Marsh's theory 

 in which the fossil caps were an essential feature. The 

 former assurftption that each column has a shell at its end 

 was no doubt a prejudiced one. Stylolitic phenomena are 

 just as numerous in the non-fossiliferous, even lithographic, 

 strata as in the highly fossiliferous ones. Only a few cases 

 have been observed by the writer where the outline of the 

 stylolite was determined by the presence of a fossil covering. 

 Frequently, however, the stylolite ends are partially covered 



