12 
Proceedings of the Royal Society of Edinburgh. [Sess. 
to the Lower Forestian or Fourth Interglacial Epoch with its temperate 
flora. The Second Arctic Bed is correlated with the Lower Turbarian or 
Fifth Glacial Period, and the Upper Forest with the Fifth Interglacial Stage. 
Dr Lewis calls special attention to the continuity of these horizons in the 
peat throughout Scotland, and to the widespread alternate depression and 
elevation of the Arctic- Alpine vegetation after the Fourth Glacial Period. 
They indicate climatic changes sufficiently pronounced to affect the distri- 
bution of the flora in the north of Britain. 
James Geikie regarded these fluctuations of climate as of considerable 
amplitude. Hence he included them in his glacial succession and described 
them as glacial and interglacial. He referred to the researches of Dr Hans 
Schreiber in the peat bogs along the northern border of the Eastern Alps, 
which furnish evidence of climatic change similar to that of our Scottish 
peat mosses. But, in my opinion, it is extremely doubtful if the fifth and 
sixth cold phases were of sufficient severity to be ranked as “ Glacial 
Epochs.” He admitted that the preceding glacial and interglacial periods 
were more prolonged and more strongly contrasted than the post-Mecklen- 
burgian series. All the available evidence indicates that the glaciation 
which accompanied the fifth glacial phase was restricted to mountainous 
areas in the Highlands, where small glaciers, in certain localities, reached 
the sea-level and deposited their moraines on the 50 feet beach. Regard- 
ing the sixth glacial phase, high-level corrie glaciers may have existed 
during this period, but there is no evidence to show that moraines of this 
stage are associated with the 25 feet beach. The peat situated in corries 
between the 3000 feet and 4000 feet level was not examined by Dr Lewis, 
but from the evidence collected in the peat at lower levels he inferred 
that, during the last glacial stage, the north of Scotland was not affected 
by great cold. 
In view of this evidence it seems more reasonable to compare the 
fluctuations of climate experienced in Scotland in post-Mecklenburgian 
time with the stadial and interstadial phases of the Alps, which are 
later than the Wtirmian or Fourth Glacial Epoch. If we eliminate the 
fifth and sixth glacial periods, then James Geikie’s classification agrees 
with that of Penck and Brtickner, based on their detailed researches in 
the Alps. 
We have now given a brief outline of the glacial succession as pro- 
pounded by James Geikie, from which it will be seen that Pleistocene time 
was characterised by a series of cold and mild periods. His views have 
been persistently opposed by the monoglacialists, who regard the intercalated 
deposits in the drifts as indicating local recessions of the ice during one 
