TRANSACTIONS OF SECTION C. 



601 



The amount of displacement cannot always be determined, for reasons wliich 

 will he aj)paient as •we proceed. 



II. The appended table gives a conspectus of the Carboniferous rocks in Craven 

 and surrounding districts : — 



It is necessary to call attention to these important facts : — 



(1 ) That there are two distinct series, difl'ering much from each other in thicH- 

 nesB and gi'ouping, 



(2) That these two series have the chief Craven faults as their common 



boundary. 



(3) That the series north of the Craven faults, which we may call the 

 Yoredale type, extends over a wide area to the north ; and that the south, or 

 Clitheroe or Bowland type, extends over an equally large area to the south. 



(4) That in the neighbourhood of the faults, which are their common 

 boundary, there appears to be very little, if any, transition from the one type to the 

 other, unless it be at the extreme ends, where the throw of the faults is consider- 

 ably less. 



(6) That the greater thicknesses are on the downthrow side of the faults. 



Keferring to the table, we see at once that it is impossible to institute any 

 comparison between the Coal-measures and Millstone grits, because, though both 

 are thrown a^rainst the faults between Ingleton and Settle on the south side, denu- 

 dation has removed them from the north side, until we get so far away from the 

 faults as to render any comparison of thickness worthless. Only small outliers of the 

 lowest of the millstone grits occur on Ingleborougli, Pennigent, Fountains Fell, kc. 

 It is, however, worthwhile to note by the way that between Clitheroe and Burnley, 

 to the south, the Carboniferous rocks are represented by upwards of three miles' 

 thickness of rocks, without either base, which is not exposed, or Upper Coal- 

 measures, which do not occur nearer than IMnnchester. 



The Yorediile series are well known to contain a number of limestones, shales, and 

 sandstones, of which the limestones are most constant, and run for many miles to 

 the north with only slight changes, much slighter than might reasonably be ex- 

 pected considering the wide areas througli which they range. 



The liotclancl shales consist of black calcareous shales only. Any limestones 

 which occur in them are very exceptional, thin, inconstant, and insignificant. They 



