SOUTH-WEST IRELAND. 203 



at the first remove all broken portions from the 

 central axis ; afterwards, as the land gradually rose, 

 it would denude back the chalk, and also form trans- 

 verse valleys along the different secondary breaks. 

 The land may even have had various upheavals and 

 lowerings, at one time being above, and another time 

 below the sea, and during all such movements it 

 would be exposed to denudation by the different forces, 

 and this appears probable from this, that most of 

 the rivers now flow through the transverse valleys; 

 but during the different risings and lowerings, such 

 places would be liable to be deepened by the sea, more 

 than the longitudinal valleys; which is the reason why, 

 when the land finally rose, they would form the chan- 

 nels most likely to be occupied by the rivers. Such 

 an estuary would also account for the marked escarp- 

 ment bounding the valley on the north, west, and 

 south, while none exists bounding the high land in 

 the centre, for the sea would form cliffs in the chalk 

 as the beds dipped away from it, but as the beds in 

 the central axis dipped towards it, .the sea could only 

 form slopes, it being unable to work back the base of 

 the escarpment as fast as' meteoric abrasion was wear- 

 ing away the upper portion. 



It has been intimated that breaks do not exist in 

 connection with the transverse valleys of the Weald ; 

 but it would appear to us that a fault must occur in 

 the valley occupied by the Eiver Ouse ; while between 



