Natural History. 123 



by banking ; and this might easily have been the case with the 

 Trent in some of the localities noticed by Mr. Bateman as at 

 Dunham and elsewhere while, in other places, the course of 

 a river is often changed by the cutting off of wandering loops, 

 in order to increase the land area ; or for other useful purposes. 



The escarpments which Mr. Bateman alludes to, and which 

 are records of very considerable antiquity, occur in various places 

 on the Trent sides ; but they are merely the result of the harder 

 rocks resisting the wear and tear of the water and atmosphere, 

 and they have no special bearing either on ice-action itself, or 

 the relative time of its occurrence. 



The only proofs that can be accepted as to when the great 

 change in the Trent's course occurred, in relation to the 

 Glacial era, must be sought for in the usual remains left by the 

 ice, such as boulder deposits, foreign erratics, and so forth ; 

 and, as these proofs are at present wanting in the area in 

 question, until they are met with, it will be impossible to say, 

 with any authority, when the change occurred. 



I quite agree, as I say in my address, that the Trent has 

 from time to time frequently gone over its old course through the 

 Lincoln Gap, especially in seasons of flood ; and, probably, it 

 did not relinquish that course for a very long period after it 

 was tapped by the drainage through the longitudinal valley on 

 the north, heading back from, and leading into, the Humber. 



There is no reason to doubt that the great ice-plough, in 

 some form or other, ran up the Trent valley ; but, owing to the 

 action of the river, and the force of the tide which, at one 

 time, extended higher up, and spread further over, the adjoin- 

 ing land than it does now all traces of this event appear to 

 have been swept away ; and the only remains of water action 

 are so far, at all events, as I am myself aware of rounded 

 pebbles and gravel, such as occur in the old course through the 

 Lincoln Gap, which the river has brought down from the 

 area it drains on the west ; and which have been by the 

 force of stream and tide assorted, and re-assorted, over and 

 over again, till the problem has become a very difficult one to 

 decipher. 



I quite admit the possibility of the Glacial period having 

 preceded, instead of having occurred after, the change in the 

 Trent's course, but at present it is an open question ; and until 

 the proofs, which ice-action alone can give, are obtained, it 

 must, I fear, remain so. 



F. M. BURTON. 



