TRANSACTIONS OF SECTION C. 741 



my geological iliapping aa for the most part correct, found reasons for dissenting 

 ■with all the groundwork on which it was founded.^ 



In combating Mr. Marr's views I offer no opinion on knolls of other localities or 

 other ages which he brings forward in support of his views. I speak only of the 

 Carboniferous knolls of which I have written, and with which I am well 

 acquainted. Speaking generally, I think the differences between us may he thus 

 summarised : 



1. Mr. Marr disagrees with my reading of the succession and thickness of the 

 rocks on the south side of the Craven Faults, and, whilst 1 consider that we have 

 two distinct successions of different thickness caused by a difference in the rate of 

 submergence in the two districts, and by shallower and deeper seas, he regards the 

 rocks on both sides as having been one st-ries of like tliickuess in orderly sequence 

 to the north, but, so to speak, shuffled by earth movements on the south of those 

 faults and repeated several times by over-thrusts. 



In illustration let us take a pack of cards, say arranged in suits as repre- 

 senting the regular country on the north side, and several packs similarly ai'ranged 

 to represent the greater thickness on the south side. Shuffle these last to repre- 

 sent the supposed disturbance and over-thrusting. Shall we always find after 

 shuffling the same general succession ? Yet over a tract reaching from Draughton 

 to Chipping and from Settle to Derbyshire, we do get such a general succession, 

 and that does not at all resemble the succession on the north side of the faults. 

 The over- thrusting to do this effectually must cover the whole of this wide area 

 comprised in three or four counties and not confine its operations to a narrow 

 disturbed belt near the Craven Faults. Is Mr. Marr prepared to make his orogenic 

 movements extend over so large an area, and thereby arrange the whole country, 

 which they break up, into so orderly a disposition ? 



2. Mr. Marr regards the great difference between the black and white lime- 

 stone, the form and constitution of the reef-knolls, the abundance in them of 

 perfect fossil forms in a well-preserved state, the conglomerates and breccias which 

 accompany them, as all being the result of what he calls orogenic movements ; iu 

 other words, of the folding, repetition, and over-thrusting of the rocks, with here 

 ejiil there reliff of pressure. More especially is the last called in as being the 

 reason for the abundant and well-preserved fossils and the change of the lime- 

 stones. 



It is extremely difficult for me to accept these views. If we could believe that 

 a black, well and thinly bedded limestone can by any physical change be converted 

 into a white crystalline mass with little visible bedding, but with abundant fossils 

 in a perfect state, we have still to learn what has become of the shales which are 

 almost always present with the black limestone. If squeezed out, as might be 

 suggested, they would at least leave partings behind, and the rock would be more 

 bedded than it is. 



Mr. Marr contemplates the likelihood of several different limestones being 

 shifted together to make one reef-knoll, but if so, are we not as likely to get the 

 thin sandstones of the Pendleside Grit sandwiched into them as welli* Yet 

 sandstones and shale-beds are unknown in the reef-knolls. 



Mr. Marr makes a number of statements about what he calls the Vs of the 

 Middle Craven Fault, His opinion is that this is a great thrust plane dipping 

 gently north, and that the Coal-measures are forced beneath the limestone, and so 

 on along its course. A bed of coal in the limestone at Ingleton is regarded by 

 him as having been forced up from imderlying Coal-measures by pressure, and not 

 as originally interbedded. Unfortunately for these views, there are no proper Vs 

 or dipping planes of faulting indicated in the map. The sinuous track of the 

 Craven Fault is not so drawn to accommodate any theory, but is merely put where 

 the exposures of rock show it to run. Its wanderings are either dictated by or 

 stand iu relation to the two principal lines of jointing in the limestone, which 

 range W.N.W. and N.N.W. Sometimes one direction, sometimes the other, has 

 the mastery. At Clapham the line is absolutely straight, and does not curve up 



' Quart. Junrn. Gvol. Soc, vol. Iv, pp. 327-361. 



