1895- THE GEOLOGY OF IPSWICH. 177 



stratified glacier mud, containing an intensely arctic flora. There 

 are no trees, only dwarf willows, birches, and herbaceous plants, such 

 as point to a temperature fully twenty degrees lower than at present. 



It has already been mentioned that glacial deposits occupy the 

 surface over great part of East Anglia. The classification and 

 correlation of these is extremely difficult ; but so far as can be made 

 out, the oldest of them are only feebly represented away from the 

 Norfolk coast, in the region where the arctic plant-bed above 

 mentioned has been found. In the neighbourhood of Ipswich the 

 most striking representative of the Glacial Epoch consists in the 

 great sheet of unstratified Boulder Clay which extends southward 

 nearly to the Thames and northward into Lincolnshire. The mode 

 of origin of this sheet of morainic material is not yet clearly under- 

 stood, for it is totally unlike anything now being formed by alpine 

 glaciers or deposited in arctic seas. We should not forget, however, 

 that an ice-sheet flowing over a flat country, where the average 

 temperature is near the freezing point, is subjected to conditions 

 entirely unlike those of an alpine glacier flowing down a steep valley 

 into a temperate climate. It is, therefore, only with the ice-sheets of 

 the Arctic and Antarctic regions, or with the wide glaciers of Alaska, 

 that we can profitably compare the ancient glaciation of the North 

 Sea basin. Space will not permit us here to discuss this question, 

 but attention may be drawn to the address by Professor T. C. 

 Chamberlin, entitled "Recent Glacial Studies in Greenland" (i). 

 The facts there brought forward throw a flood of light on some of the 

 obscure points in the glaciation of East Anglia, and anyone studying 

 the intricate glacial deposits of the Norfolk coast should read 

 Professor Chamberlin's description and examine his photographs. 



One very puzzling peculiarity of the East Anglian Boulder Clays 

 is likely to come forward prominently at the Ipswich meeting. This 

 is the strange mixture of erratics from different districts. Blocks 

 from Yorkshire, and perhaps Scotland, are mingled promiscuously 

 with others from the islands in the Baltic or from the coast of 

 Norway. There has been much discussion as to the meaning of this 

 mixture; but, from the fact that many of the boulders are worm- 

 eaten beach stones, subsequently glaciated, it is probable that most 

 of them were scattered over the bed of the North Sea by floating ice, 

 to be afterwards merely ploughed up and carried forward by the 

 ice-sheet. 



It might be thought that so recent a period as that of the dying 

 away of the arctic cold would be thoroughly understood ; but such 

 is not the case, one of the most difficult problems in Pleistocene geology 

 being to make out the relation of Palaeolithic man to the Glacial 

 Epoch. In this respect the County of Suffi^lk is particularly well 

 situated, for the deposits newer than the Boulder Clay are very 

 peculiar and often highly fossiliferous. At Stutton, on the north side 

 of the River Stour, for instance, is found a brick-earth with elephant 



