772 ABSTRACTS OF PAPERS 



upward and was located not far below the surface. In all cases the folds 

 were below the limits of frost action, and were also generally below the zone 

 of normal surface weathering. This was shown by the fact that the anticlines 

 often extended into the blue unaltered shale. In several cases where the 

 flexed strata were traceable for a vertical distance of 10 feet, 2 to 3 feet at the 

 bottom were found to occur in blue shale, while the remainder was stained 

 yellow from the oxidation of iron. It is evident that the various folds have 

 no connection with each other, and therefore are not due to secular move- 

 ments of the earth's crust. The anticlines must, therefore, have been formed 

 by local pressures which were caused by some force inherent to the shales. 

 Analyses of the Chagrin shales from various places in the vicinity of Cleve- 

 land show that sulphur is always present in smaller or larger amounts. Such 

 an analysis, although not complete, is given from Chagrin shale used by the 

 John Kline & Son Brick Company as follows : 



SlO, 57 . 80 



AljOa ...21.11 



FejOj 5.80 



MgO 1 . 73 



CaO 0.80 



^^'^ \ 2 95 



HiO 6.01 



SO, 1 . 22 



97.42 



The sulphur is undoubtedly present in the form of iron sulfide as pyrite, or 

 possibly marcasite. As was previously stated, concretions or local enrichment 

 of these minerals and clay ironstones are often present in these shales. It 

 might have been possible that the force which caused the formation of the 

 concretions or of concretionary layers could have exerted enough upward 

 pressure to form the anticlines, or at least to aid in their formation. 



The writer, however, is inclined to believe that the sulfides have been some- 

 what concentrated at various points by concretionary action. They have 

 then altered to iron sulfate, and have thereby so increased in volume that 

 local pressures have been produced, which in turn have flexed the shale. The 

 specific gravity of marcasite and pyrite ranges from 4.85 to 5.10, while that of 

 ferrous sulfate varies from 1.79 to 1.90. It is possible that an iron alum 

 might have been formed at the same time, but the specific gravity would be 

 about the same as that of the iron sulfate. The change from iron sulfide to 

 iron sulfate or alum would therefore require nearly a threefold increase in 

 volume which might well produce sufficient force to upheave the strata into 

 anticlinal folds. In several places the formation of copperas and alum-like 

 compounds was observed. The rapid weathering of the shales soon destroys 

 nil traces of structure, so that at the present writing, which is over a year 

 af'er the anticlines were first observed, few, if any, are noticeable on the 

 surface. 



Conclusion 



The local anticlines observed in the Chagrin shales were probably caused by 

 pressure due to the nearly threefold increase in volume which results when 

 iron sulfides alter to iron sulfate and alum-like compounds. The anticlines 



