E0SS1LIFER0TJS PEBBLES IN" THE DKIFT IN WARWICKSHIRE. 435 



From this source at an earlier period the Upper and Lower Triassic 

 pebbles were, as I have inferred, probably derived ; and hence it 

 formed the supply of a large proportion of the Midland Drift in the 

 districts referred to in this paper. Mr. Etheridge suggested the 

 possibility of the Wenlock Limestone, lately noticed in a boring at 

 "Ware, dipping to the south. This surmise, Mr. Keeping says, has 

 since proved to be correct ; and therefore a further extension of 

 ancient Silurian and Cambrian rocks northwards is still more 

 probable. 



This denudation of these old rocks may have come to a close 

 during the Cretaceous or even some later period, when they finally 

 disappeared beneath the sea, having been going on for ages, perhaps 

 commencing at a date somewhat anterior to the deposition of the 

 Banter. There are, perhaps, few geological problems more difficult 

 to solve than the history (range, distribution, and origin) of these 

 latest Pleistocene deposits, such as clays, till, gravel, and sands under 

 the name of Drift, which are so widely spread and often composed of 

 such heterogeneous materials. Where made up for the most part of 

 formations present in situ in the immediate neighbourhood or not 

 very far off, the solution is comparatively easy ; but where they 

 are mainly derived from a great distance, perhaps here and there 

 from foreign sources, as some of our Midland Drift may be, it is very 

 puzzling and extremely difficult to determine whence they originally 

 came and by what means they were transported. Though many 

 able papers have been written upon this subject, much yet remains 

 to be done both here and elsewhere before definite and satisfactory 

 results can be obtained. 



[Note, July 21. — It has since been determined that some of the 

 Brachiopoda belong to the Caradoc.J 



Discussion. 



The President remarked that the subject was a difficult one, 

 but the species, as stated by Mr. Brodie, were no doubt correct. 

 At Budleigh Salterton it was easy to tell whence many of the 

 pebbles had been derived ; but in the Midland counties it was most 

 difficult. 



Mr. Usshee said that the occurrence of the same fossils did not 

 prove that the pebbles were from the same area, and that the Drift 

 of the paper was not quite clear from its title. 



Prof. Bonnet stated that the author had not expressed this 

 opinion in his paper ; he thought it a most valuable addition to our 

 knowledge, and was glad that such a contribution had been evoked 

 by his own slight paper. He thought it almost certain that there 

 were two sources for the quartzites, and that all the fossiliferous 

 specimens could not have come from the Lickey, as some had been 

 found at Nottingham. Probably ancient rocks had extended to the 

 north-east of England, beyond those discovered in borings at 

 Northampton, and to the north-east of those exposed at Charnwood. 



