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same way. Now, as the rocks throughout the Cumberland Coal- 

 field are of the same argillaceous and arenaceous nature it 

 might be expected that the Permian staining would originally 

 extend everywhere to about the same depth, that is to say, its 

 lower limit would be parallel to the base of the overlying Permians. 

 These latter rocks, as is known, are unconformable to the Coal 

 Measures, and therefore the staining would cut across the bed 

 planes of those rocks in such a way as to suggest that the tinted 

 strata were unconformable to those below them. It is thus clear 

 that if the unconformity of the Permians were sufficiently great we 

 should have a tinted band of Coal Measures which would include 

 the "rise" part of every seam in the field. 



The unconformity actually occurring in the district under con- 

 sideration is of this extent, but the inferences which have just been 

 drawn, and which I hold to be legitimate deductions from the 

 premises, are not paralleled by the facts, and therefore I doubt the 

 validity of those premises; in other words, I dispute that the 

 purple-grey rocks are stained Lower Coal Measures. For in the 

 first place we find that at Croft Pit, near Whitehaven, they 

 extend only to a depth of one hundred and seventy-five feet from 

 the base of the Permians, whereas at Mealsgate, where the Permians 

 have been removed, the purple-grey rocks occur more or less 

 throughout a depth of five hundred and fifty-two feet. Then again 

 there is not a single place throughout the whole Coalfield, so far 

 as I know, where purple-grey rocks occur below any well known 

 seam in Lower Coal Measures,* which there certainly should have 

 been if the purple-grey rocks which I include in the Whitehaven 

 Sandstone series are simply Lower Coal Measures that have been 

 stained, as supposed by Mr. Holmes. Not one of the many seams 

 worked in the Cumberland Coalfield has ever been worked or 

 traced from the purple-grey rocks into the darker rocks of the 

 Lower Coal Measures, or vice versa. This fact to my mind is 

 perfectly conclusive against Mr. Holmes' argument. Again, if the 

 purple-grey rocks were simply stained Lower Coal Measures, their 



* This expression is used here and throughout this paper in the same sense 

 as in "The Structure of the Cumberland Coalfield." 



