GLACIAL SUCCESSION IN EUROPE. 143 



filled with ice. The plant-bearing beds are in their turn covered by the ground-moraine 

 of a later and more extensive glaciation. To bring about the glacial conditions that 

 obtained before the formation of the breccia, the snow-line, according to Pence, must 

 have been at least 1000 metres lower than now ; while, to induce the succeeding 

 glaciation, the depression of the snow-line couJd not have been less than 1200 metres. 

 These observations have been extended to many other parts of the Alps, and the con- 

 clusion arrived at by Professor Penck and his colleagues, Professor Bruckner, and Dr 

 Bohm, is briefly this, — that the maximum glaciation of those regions did not fall in the 

 " first " but in the " second " Alpine glacial epoch. 



The glacial phenomena of Northern and Central Europe are so similar — the climatic 

 oscillations which appear to have taken place had so much in common, and were on so 

 grand a scale — that we cannot doubt they were synchronous. We may feel sure, 

 therefore, that the epoch of maximum glaciation in the Alps was contemporaneous with 

 the similar epoch in the north. And if this be so, then in the oldest ground-moraines of 

 the Alps we have the records of an earlier glacial epoch than that which is represented 

 by the lower boulder-clays of Britain and the corresponding latitudes of the Continent. 

 In other words, the Hotting flora belongs to an older stage of the Glacial Period than 

 any of the acknowledged interglacial accumulations of Northern Europe. The character 

 of the plants is in keeping with this conclusion. The flora has evidently much less 

 connection with the present flora of the Alps than the interglacial floras of Britain and 

 Northern Europe have with those that now occupy their place. The Hotting flora, 

 moreover, implies a considerably warmer climate than now obtains in the Alpine regions, 

 while that of our interglacial beds indicates a temperate insular climate, apparently much 

 like the present. 



The high probability that oscillations of climate preceded the advent of the so-called 

 " first" mer de glace of Northern Europe must lead to a re-examination of our Pliocene 

 deposits, with a view to see whether these yield conclusive evidence against such climatic 

 changes having obtained immediately before Pleistocene times. By drawing the line of 

 separation between the Pleistocene and the Pliocene at the base of our glacial series, the 

 two systems in Britain are strongly marked off the one from the other. There is, in 

 short, a distinct " break in the succession." From the Cromer Forest-bed, with its 

 abundant mammalian fauna and temperate flora, we pass at once to the overlying Arctic 

 freshwater bed and the superjacent boulder-clay that marks the epoch of maximum 

 glaciation.* Amongst the mammalian fauna of the Forest-bed are elephants {Elephas 

 meridionalis, E. antiquus), hippopotamus, rhinoceros (R. etruscus), horses, bison, boar, 

 and many kinds of deer, together with such carnivores as bears, Machwrodus, spotted 

 hyaena, &c. The freshwater and estuarine beds which contain this fauna rest immediately 

 upon marine deposits (Weybourn Crag), the organic remains of which have a decidedly 

 Arctic facies. Here, then, we have what at first sight would seem to be another break 



* In some places, however, certain marine deposits (Leda-myalis bed) immediately overlie the Forest-bed. See 

 postea, footnote, p. 145. 



VOL. XXXVII. PART I. (NO. 9). Z 



