142 PROFESSOR JAMES GETKIE ON THE 



the earliest of our recognised glacial epochs. With each recurring cold period the ice- 

 sheets and glaciers successively diminished in importance. That is one of the outstanding 

 facts with which we have to deal. Whatever may have been the cause or causes of 

 glacial and interglacial conditions, it is obvious that those causes, after attaining a 

 maximum influence, gradually became less effective in their operation. Such having been 

 the case, one can hardly help suspecting that our epoch of greatest glaciation may have 

 been preceded by an alternation of cold and genial stages analogous to those that followed 

 it. If three cold epochs of progressively diminished severity succeeded the epoch of 

 maximum glaciation, the latter may have been preceded by one or more epochs of 

 progressively increased severity. That something of the kind may have taken place is 

 suggested by the occurrence of the old moraine of that great Baltic glacier that preceded 

 the appearance of the most extensive mer de glace of Northern Europe. The old moraine 

 in question, it will be remembered, underlies the " lower diluvium." Unfortunately, the 

 very conditions that attended the glaciation of Europe render it improbable that any 

 conspicuous traces of glacial epochs that may have occurred prior to the period of 

 maximum glaciation could have been preserved within the regions covered by the great 

 inland ice. Their absence, therefore, cannot be held as proving that the lower boulder- 

 clays of Britain and Northern Europe are the representatives of the earliest glacial epoch. 

 The lowest boulder- clay, I believe, has yet to be discovered. 



It is in the Alpine lands that we encounter the most striking evidence of glacial 

 conditions anterior to the epoch of maximum glaciation. The famous breccia of 

 Hotting has already been referred to as of interglacial age. From the character of its 

 flora, Ettinghausen considered this accumulation to be of Tertiary age. The assemblage 

 of plants is certainly not comparable to the well-known interglacial flora of Durnten. 

 According to the researches of Dr R. von Wettstein,* the Hotting flora has most affinity 

 with that of the Pontic Mountains, the Caucasus, and Southern Spain, and implies a 

 considerably warmer climate than is now experienced in the Inn valley. This remarkable 

 deposit, as Dr Penck pointed out some ten years ago, is clearly of interglacial age. His 

 conclusions were at once challenged, on the ground that the flora had a Tertiary and not 

 a Pleistocene facies ; consequently, it was urged that, as all glacial deposits were of 

 Pleistocene age, this particular breccia could not be interglacial. But in this, as in 

 similar cases, the palaeontologist's contention has not been sustained by the strati- 

 graphical evidence, and Dr Penck's observations have been confirmed by several highly- 

 competent geologists, as by MM. Bohm and Du Pasquier. The breccia is seen in several 

 well-exposed sections resting upon the moraine of a local glacier which formerly descended 

 the northern flanks of the Inn Valley, opposite Innsbruck, where the mountain-slopes 

 under existing conditions are free from snow and ice. Nor is this all, for certain erratics 

 appear in the breccia, which could only have been derived from pre-existing glacial 

 accumulations, and their occurrence in this accumulation at a height of 1150 metres 

 shows that before the advent of the Hotting flora the whole Inn Valley must have been 



* Sitzungsberichte d. Kais. Acad. d. Wissensch. in Wim } mathem.-naturw. Classe, Bd. xcvii. Abth. i., 1888. 



