560 REPORT— 1889. 



ty M. Falsan, the eminent French glacialist. Covering the plateaux of the DombS; 

 and widely spread throughout the valleys of the Rhone, the Aiu, the Isere, &c., in 

 France, there is a deposit of loss, he says, which has been derived from the washing 

 of the ancient moraines. At the foot of the Alps, where black schists are largely 

 developed, the loss is dark grey ; but west of the secondary chain the same deposit 

 is yellowish, and composed almost entirely of silicious materials, with only a very 

 little carbonate of lime. This limon or loss, however, is very generally modified 

 towards the top by the chemical action of rain, the yellow loss acquiring a red 

 colour. Sometimes it is crowded with calcareous concretions ; at other times it has 

 been deprived of its calcareous element and converted into a kind of pulverulent 

 silica or quartz. This, the true loss, is distinguished from another lehm, which 

 Falsan recognises as the product of atmospheric action — formed, in fact, in place 

 from the disintegration and decomposition of the subjacent rocks. Even this lehm 

 has been modified by running water — dispersed or accumulated locally, as the case 

 may be.^ 



All that we know of the loss and its fossils compels us to include this accumu- 

 lation as a product of the Pleistocene period. It is not of postglacial age — even 

 much of what one may call the ' remodified loss' being of Late Glacial or Pleisto- 

 cene age. I cannot attempt to give here a summary of what has been learned 

 within recent years as to the fauna of the loss. The researches of Nehring and 

 Liebe have familiarised us with the fact that at some particular stage in the 

 Pleistocene period a fauna like that of the alpine steppe-lands of Western Asia 

 was indigenous to Middle Europe, and the recent investigations of Woldfich have 

 increased our knowledge of this fauna. At what horizon, then, does this steppe- 

 fauna make its appearance ? At Thiede Dr. Nehring discovered in so-called loss 

 three successive horizons, each characterised by a special fauna. The lowest of 

 these faunas was decidedly arctic in type ; above that came a steppe-fauna, which 

 last was succeeded by a fauna comprising such forms as mammoth, woolly rhino- 

 ceros. Bos, Cervus, horse, hysena, and lion. Now, if we compare this last fauna 

 with the forms which have been obtained from true postglacial deposits — those 

 deposits, namely, which overlie the younger boulder-clays and flood-accumula- 

 tions of the latest glacial epoch, we find little in common. The lion, the mam- 

 moth, and the rhinoceros are conspicuous by their absence from the postglacial 

 beds of Europe. In place of them we meet with a more or less arctic fauna, and a 

 high-alpine and arctic flora, which, as we all know, eventually gave place to the 

 flora and fauna with which Neolithic man was contemporaneous. As this is the 

 case throughout North-Western and Central Europe, we seem justified in assigning 

 the Thiede beds to the Pleistocene period, and to that interglacial stage which 

 preceded and gradually merged into the last glacial epoch. That the steppe-fauna 

 indicates relatively drier conditions of climate than obtained when perennial snow 

 and ice covered wide areas of the low ground goes without saying ; but I am 

 unable to agree with those who maintain that it implies a dry-as-dust climate, like 

 that of some of the steppe- regions of our own day. The remarkable commingling 

 of arctic and stejipe-faunas discovered by Woldfich in the Bohmerwald ^ shows, I 

 think, tliat the jerboas, marmots, and hamster-rats were not incapable of living in 

 the same regions contemporaneously with lemmings, arctic hares, Siberian social 

 voles, &c. But when a cold epoch was passing away the steppe-forms probably 

 gradua ly replaced their arctic congeners, as these migrated northwards during the 

 continuous amelioration of the climate. 



If the student of the Pleistocene faunas has certain advantages in the fact that 

 he has to deal with forms many of which are still living, he labours at the same 

 time under disadvantages which are unknown to his colleagues who are engaged 

 in the -tudy of the life of far older periods. The Pleistocene period was distin- 

 guishe 1 above all things by its great oscillations of climate — the successive changes 

 being lepeated, and producing correlative migrations of floras and faunas. We 

 know that arctic and temperate faunas and floras flourished during interglacial 



' F ilsan : La Periode glaciaire, p. 81. 



« W .Idfich : Sitzungsh. d. kais. Akad. d W. math. nat. CI., 1880, p. 7 ; 1881 , 

 p. 177; 1883, p. 978. 



