214 



The irregulju- 1)e(ldiiig- of the Devonian at Oass, Cass County, is quite- 

 marked, and the same is true of the Geneva beds in some parts of South- 

 ern Indiana. A fine exposure of mixed bedding is to be seen in the 

 Geneva limestone at the Cave mill park, v^hich presents an eighteen-foot 

 wall of discontinuous, uneven and distorted stratification, overlying what 

 appears to be Louisville limestone. This seems to be the formation from 

 which Mr. Kindle collected a number of Devonian fossils, three-quarters of 

 a mile farther up the creek, opposite Charles' mill, and the equivalent 

 of the Devonian bluffs near Hartsville. According to Mr. Price, irregular 

 bedding is common above the Waldron sliale in Rush County. It is prob- 

 able that further search will reveal many more irregularities that are now 

 obscured by weathering. The irregular liedding of the Louisville and 

 Geneva limestones is probably the result of marine currents, and it cer- 

 tainly is not necessary to invoke a local uplift or convulsion of nature to 

 account for its origin or that of the unconformities. 



No unconformities liave been reported from the LTpper Helderberg, but 

 there is evidence that the Niagara limestone and New Albany black shale 

 are not conformable at Delphi. 



By Mr. Foerste and others the Louisville beds are referred to the 

 Niagara epoch, and this may be their place if based on paleontologic evi- 

 dence. Its horizon, however, can not be established by the existence of a 

 few minor unconformities at the top of Louisville limestone. If uncon- 

 formities are conceded to have occurred during the Niagai'a epoch or 

 Silurian age, in the Wabash Valley, they certainly show that the changes 

 in the coast line necessary to tlieir formation, whether submarine or 

 aerial, did not destroy a large per cent, of the fauna in existence before 

 the erosion period began. Of course it is conceded that many of the spe- 

 cies found in the Waldron sliale are peculiar to that formation, but many 

 of them also came up from the preceding epoch. Tlierefore. the Upper 

 Niagara and Geneva limestone unconformities have very little significance 

 in determining the age of the formation Ijetween which they occur. 



An interesting question arises whether the Waldron shale can be cor- 

 ivlated with the quari-y stone of Wabash Coiuity. Not enough is known 

 to give anything like certainty to what now may be said on the subject, 

 Init it may not be improper to call attention to a few observations which 

 indicate that they occupy the same horizon. It is generally Jcnown that 

 the Waldron shale is often highly calcareous, with intercallated plates 

 of limestone, and changes to thin layers of limestone as it is traced north- 



