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CHAPTER X. 



PEKMIAN STRATA. 



IN England there are certain red strata, known as PER- 

 MIAN, which occupy a sort of debatable ground, lying 

 between the Carboniferous and New Red or Triassic 

 series. Sometimes they have been classed with the 

 former, sometimes with the latter, by those who like 

 to insist on hard and fast lines of division between each 

 formation. These strata, lying not quite conformably 

 either with the underlying or the overlying formation, 

 I prefer to consider as in some sense transition beds, 

 making one of the steps in that change of the physical 

 geography of our area which put an end to the develop- 

 ment of Coal-measures, and made it possible under new 

 conditions for the Permian strata to be deposited. 



They are usually divided (as in Germany) into two 

 subformations, viz. : 



Magnesian Limestone and Marl Slate, 

 Eothe-todteliegende. 



The higher English beds in certain areas consist chiefly 

 of Magnesian Limestone or Dolomite, interstratified 

 with certain marls, and the lower of red marls, sand- 

 stones, and conglomerates. But if we take England as 

 a whole this division does not hold good, for in the 

 eastern part of England the Magnesian Limestone often 

 lies directly on the Coal-measures, and in Lancashire and 



