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Indiana University Studies 



ding planes having no evidence of stylolites. They are very 

 common at the junction of cross-bedded and horizontally 

 bedded strata in the Salem limestone. They often sharply 

 mark the parting between beds of distinctly different lithologic 

 characteristics. Contrary, however, to the observations of 

 Hopkins (Hopkins and Siebenthal, 1897, p. 307), that they 

 never run across the grain, the writer has observed cases 

 where even large seams leave the bedding planes and cut 

 across the lamination (see Fig. 17). In one instance, an ap- 



FiG. 17. — Stylolite-seam which leaves the bedding plane and 

 cuts across the lamination of the upper stratum at an angle 

 of about 20 degrees. From a quarry of the Consolidated 

 Stone Company, Hunter Valley district, Monroe County, 

 Ind. 



parent fault-surface, cutting the bedding at an angle of about 

 60°, has developed a slightly stylolitic nature. 



The many minute, shai-ply-toothed sutures, varying from 

 an almost microscopic width up to a fraction of an inch or so, 

 usually follow the lamination, but occasionally cut across the 

 laminae at a small angle (see Fig. 16). Their general direc- 

 tion, however, as in the case of larger stylolite-seams, is hori- 

 zontal. In some instances they follow the laminae of a 

 false-bedded stratum. 



The frequency of occurrence of stylolite-partings is quite 

 variable in different geologic horizons, and in different locali- 



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