PBESIDENTIAL ADDRESS. 557 



Some evidence for changes of climate in the uplands durino; post-glacial times 

 has been recently obtained from the study of peat mosses by Mr. F.J. Lewis ; and 

 these changes have been arranged according to the scheme/ with Professor 

 Geikie's approval,- by supposing that only certain parts of the sequence are 

 represented in some places. Thus, in the Highland mosses (and presumably also 

 on Cross Fell, in Cumberland),^ where arctic plants are found at the base of the 

 peat, it is assumed that earlier beds have been swept away by glaciation ; while 

 in the Southern Uplands an additional glacial and interglacial epoch are supposed 

 to be represented. But as in all cases the peats lie above the glacial drifts, their 

 suggested classification into five stages, ranging from the ' Mecklenburgian ' to 

 the ' Upper Turbarian,' seems highly speculative ; and it has yet to be decided 

 whether the changes indicated by the plants are so great as to fulfil the require- 

 ments of the hypothesis. In any case, it is not likely that many British geologists 

 will be found willing to regard the hill peats as other than post-glacial. 



Smnmary. 



My subject has proved unwieldy ; and in merely sketching its outlines I am 



uneasily aware that I have overstepped the usual bounds of an Address. My 



conclusions — if the term be applicable to results mainly negative — are as 

 follows: — 



1. In the present state of opinion regai'ding the glacial sequence and its inter- 

 pretation in North Europe, it is premature to attempt the arrangement of the 

 British drifts on this basis. 



2. No proof of mild interglacial epochs, or even of one such epoch, was 

 discovered during the examination of certain typically glaciated districts in 

 England, Ireland, and the Isle of Man ; and the drifts in these areas yielded 

 evidence that from the onset of the land ice to Its final disappearance there was a 

 period of continuous glaciation, during which the former sea-basins were never 

 emptied of their ice-sheets. 



3. The ' middle glacial ' sands and gravels of our islands afford no proof of 

 mild interglacial conditions or of submergence. In most cases, if not in all, 

 they represent the fluvio-glacial material derived from the ice-sheets. 



4. The British evidence for the Interglacial hypothesis, though requiring 

 further consideration in some districts, is nowhere satisfactory. Most of the 

 fossiliferous beds regarded as interglacial contain a fauna and ilora compatible 

 with cold conditions of climate ; and in the exceptional cases where a warmer 

 climate is indicated, the relation of the deposits to the boulder-clays is open to 

 question. 



6. The British Pliocene and Pleistocene deposits appear to indicate a progressive 

 change from temperate to sub-arctic conditions, which culminated in the production 

 of great ice-sheets, and then slowly recovered. 



6. During the long period of glaciation the margins of the ice-lobes underwent 

 extensive oscillations, but there is evidence that the different lobes reached their 

 culmination at different times, and not simultaneously. The alternate waxing and 

 waning of the individual ice-sheets may have been due to meteorological causes of 

 local, and not of general influence. 



Let me add, in closing, that it would have been a more gratifying task if, instead 

 of probing into these outstanding uncertainties, I had chosen to deal only with 

 the many and great advances that have been made during the last twenty-five 



' 'The History of the Scottish Peat Mosses and their Relation to the Glacial 

 Period.' Scottuh Geogr. May., vol. xxii. (lOOfJ), pp. 241-252; see also Trans. Royal 

 Soc. Edinburgh, vol. xli. (Ilt05), part iii., No. 28. 



■^ ' Late Quaternary Formations of Scotland.' ZtiUclvrift f-iir Qletscherltunde, 

 vol. i. (1!)0G), pp. 21-30. 



' K. .1. Lewis, ' Interglacial and Postglacial Beds of the Cross Fell District.' Rep. 

 British Assoc, tor 1904, pp. 798-799. 



