132 The Rev. W. Conybeare oji the 



The proofs which the deep vallies, separating the detached emi>- 

 nences characteristic of this system, afford of their formation by an 

 agent which has excavated and scooped out as it were portions of 

 the solid strata, have been most ably and clearly detailed by Dr. 

 Richardson in the appendix to the Statistical Survey of Antrim. 

 The general appearances he describes are common (it should be re- 

 marked) to the vallies of all countries composed of nearly horizontal 

 strata ; but one phenomenon, as stated by him, seems almost peculiar 

 to Antrim, namely, that the materials so removed have been en- 

 tirely carried off, leaving no traces behind them. This circumstance 

 seems to incline Dr. Richardson to consider the agent which has 

 acted in the manner described, as some unknown and undiscoverable 

 cause, and to hesitate in receiving the common and surely probable 

 opinion which regards diluvial currents as presenting a satisfactory 

 .solution ; but it must be remembered that the solitary instances he ad- 

 duces can never weigh against the great majority of cases in which 

 the fragments of the rocks so destroyed not only occur in abundance 

 where they might be expected, but exhibit the most unequivocal 

 marks of their having experienced the action of agitated waters. 

 He who has examined the valley of the Thames from its source 

 downwards can be at no loss for illustrations of these positions, 

 the vast deposits of waterworn debris of oolite which this valley 

 presents where it traverses the range of hills occupied by this rock, 

 and those of flint pebbles where it crosses the chalky hills of the 

 Chilterns, will instantly occur to his mind. It is surely more phi- 

 losophical to suppose that the violence of the currents has swept 

 away the debris of the Antrim excavations into Lough Neagh on the 

 one side, and into the sea on the other, than that these excavations 

 owe their origin to some unknown cause, distinct from that which 

 appears to have produced all others. 



