554 TRANSACTIONS OF SECTION C. 



Glacial,' aion;T with oflier plant-beds with a similar flora wbieh lie directly upon 

 the glacial drift in many parts of Britain, it is difficult to know where,'iii the 

 English glacial sequence, we are to place the supposed interglacial epoch represented 

 by the temperate plant-beds of Hoxne and Ilitchin. 



From such deposits we regain at the most a mere fragment of the whole flora 

 of the time; and I think there is a danger that we lay too much weight upon 

 accidental instances of preservation. Is it not possible that the northern flora 

 lingered for some time in suitable places alongside the re-advancing temperate 

 plants? That some minor oscillations of climate have occurred during post- 

 glacial times may be admitted ; but, so far as'my experience has reached,"l have 

 not yet seen any evidence for a general reversal of climatic conditions after the 

 accumulation of the Upper boulder-clay of eastern and western England. 



ScoTLANB. — The Scottish evidence still remains to be considered, and I must 

 confess to a cei-tain timidity in venturing across the Border into this stronghold of 

 the ' Interglacialismu?/ especially as my personal acquaintance with the Scottish 

 drifts is slight. But, armed with the experience gained south of the Border, I will 

 attempt the raid. 



On the eastern side of Scotland the drifts broadly resemble those of the east 

 of England; while in western Scotland they appear to be more nearly akin to 

 those of Wales and the west of Ireland; with this difference, that there is more 

 plentiful evidence for local valley -glaciers during the waning stages of the Glacial 

 Period. 



The evidence for the Helvetian Epoch of deglaciatiou in Scotland is even 

 more confused and indefinite than in England. Some sporadic patches of peaty 

 and silty material associated with the boulder-clay are supposed to represent a 

 continuous land surface during an epoch when previous ice-sheets had entirely 

 melted away ; and similar patches of marine origin are interpreted as the product 

 of a Helvetian submergence with which this interglacial episode terminated. 

 But the evidence is so M'idely scattered and so diverse in character that it leaves 

 us sceptical, in spite of the admirable skill with which its arrangement into the 

 scheme is effected. 



The land deposits, almost without exception, were observed in temporary 

 exposures of small extent that are not available for further study, and in several 

 instances doubt has arisen as to their exact relations with the bo'iilder-clay. The 

 ' elephant-bed ' at Kilmaurs, Ayrshire, appears generally to have underlain the 

 boulder-clay, and was originally supposed to be pre-glacial, though on other evi- 

 dence it is regarded as intercalated between two boulder-clays where both happen 

 to be present.' The plant-bed near Airdrie, Lanarkshire, as we learn from the 

 careful description of the late James Bennie,^ occurred in wisps in the boulder- 

 clay, and was evidently displaced ; and, moreover, as in other of these Scottish 

 plant-beds, the flora is of arctic character. There are, in fact, according to Mr. 

 C. Reid, only three localities at present known in Scotland where plants indicative 

 of a temperate climate have been discovered in beds supposed to be intercalated 

 with boulder-clay, viz., Cowden Glen (Renfrew), Redhall, and Ilailes (both near 

 Edinburgh), and in each case Mr. Reid has found such anomalous results in his 

 critical examination of the plant remains said to have been obtained from the 

 deposits that, in spite of his usual willingness to adopt the Interglacial hypothesis, 

 he has been led to doubt the evidence for their ' interglacial ' position.' Professor 

 J. Geikie, it is true, has challenged Mr. Eeid's results ; ^ and as it is stated that 

 the Cowden Glen section has been obliterated for many years, the Hailes inter- 

 glacial deposit long since removed, and the Redhall quarry now obscure, there 

 seems no likelihood of further evidence on either side ; which is the more to be 



' Great Ice Age, 3rd ed., pp. 133-135. 



" ' On the Occurrence of Peat with Arctic Plants in Boulder Clay at Faskine, near 

 Airdrie.' Trwns. Geol. Soc. Glasgow, vol. x. (1894), pp. 148-152. 



' ' On Scottish Interglacial Deposits.' Geol. Mag., dec. iv., vol, ii. (1895), pp. 1-3. 

 * 'Scottish Interglacial Beds' (letter). JW^., pp. 283-284. 



