228 MR. E. W. BINNEY ON THE 



strata. Some authors have described both these as faults. 

 In the beginning of this century certain geologists and 

 practical miners often supposed that when the Coal-mea- 

 sures disappeared under the Permian and Triassic strata^ 

 generally then known as " red ground/^ they were cut off 

 by a faulty and it was useless trying to follow them. 

 " Ked-rock faults '^ were then used in the same sense, 

 whether found on the rise or dip of the strata. Now it is 

 of the utmost importance that these two classes of pheno- 

 mena should be carefully distinguished; and accordingly 

 most geologists have done so^ and termed the former a 

 fault, because the strata are there displaced, and the latter 

 an overlap, because the underlying strata are not displaced, 

 but simply covered up by the superior strata. 



Of course when Coal-measures disappear on their dip 

 under superior beds, they can generally be followed, pro- 

 vided there are no faults ; and if there are faults, the beds 

 can be found at some depth or other. Owing to these 

 circumstances, Permian and Triassic strata have often been 

 supposed to indicate the presence of coal under them. 

 No doubt they do where profitable seams of coal disap- 

 pear under them; but when millstone-grit or mountain- 

 limestone in Lancashire and Cheshire disappear on their 

 dip under Permian or Triassic strata, such strata do not 

 give any evidence of the existence of profitable coal seams 

 under them, but only of beds of mountain-limestone or 

 millstone- grit seen near them. This holds good only for 

 the southern or midland districts of England, so far as 

 profitable coal is concerned ; for it is well knovni that in 

 Scotland both these deposits contain valuable seams of 

 coal. 



Mr. Hull, in his map of the district, lays down the 

 country from Macclesfield to Stockport, so far as it relates 

 to the Coal-measures, by supposing the latter strata on 

 their dip to be bounded by what he terms the '^ Red- 



