I 



TRANSACTIONS OF SECTION C. 559 



this remarkable accumulation. By many it is considered to be an aqueous deposit ; 

 others, Ibllowinp^ Kichthofen, are of opinion that it is a wind-blown accumulation ; 

 while some incline to the belief that it is partly the one and partly the other. Nor 

 do the upholders of these various hypotheses agree amongst themselves as to the 

 precise manner in which water or wind has worked to produce the observed results. 

 Thus, amongst the supporters of the aqueous origin of the loss, we find this attri- 

 buted to the action of heavy rains washing over and re-arranging the material of 

 the boulder-clays.' Many, again, have held it probable that loss is simply the 

 finest loam distributed over the low grounds by the flood-waters that escaped from 

 the northern inland ice and the meis de glace of the Alpine lands of Central Europe. 

 Another suggestion is that much of the material of the loss .may have been derived 

 from the denudation of the boulder-clays by flood-water during the closing stages 

 of the last cold period. It is pointed out that in some regions at least the loss is 

 underlaid by a layer of erratics, which are believed to be the residue of the denuded 

 boulder-clay. We are reminded by Klockmann - and Wahnschaft'e ^ that the 

 inland ice must have acted as a great dam, and that wide areas in Germany &c. 

 would be flooded, partly by water derived from the melting inland ice, and partly 

 by waters flowing north from the hilly tracts of Middle Germany. In the great 

 basins thus formed there would be a commingling of tine silt-material derived from 

 north and south, which would necessarily come to form a deposit having much the 

 same character throughout. 



From what 1 have myself seen of the loss in various parts of Germany, and 

 from all that I have gathered from reading and in conversation with those who 

 have worked over loss-covered regions, I incline to the opinion that loss is for the 

 most part of aqueous origin. In many cases this can be demonstrated, as by the 

 occurrence of bedding and the intercalation of layers of stones, sand, gravel, &c., 

 in the deposit ; again, by the not infrequent appearance of fresh-water shells ; but 

 perhaps chiefly by the remarkable uniformity of character which the loss itself 

 displays. It seems to me reasonable also to believe that the flood-waters of glacial 

 times must needs have been highly charged with finely-divided sediment, and that 

 such sediment would be spread over wide regions in the low grounds — in the slack- 

 waters of the great rivers and in the innumerable temporary lakes which occupied, 

 or partly occupied, many of the valleys and depressions of the land. There are 

 different kinds of loss or loss-like deposits, however, and all need not have been 

 formed in the same way. Probably some may have been derived, as "NVahnsclmfl'e 

 has suggested, from the denudation of boulder-clay. Possibly, also, some loss may 

 owe its origin to the action of rain upon the stony clays, producing what we in this 

 country would call ' rain-wash.' Tliere are other accumulations, however, which 

 no aqueous theory will satisfactorily explain. Under this category comes much of 

 the so-called Bergliiss, with its abundant land -shells, and its generally unstratitied 

 character. It seems likely that such loss is simply the result of subaerial action, 

 and owes its origin to rain, frost, and wind acting upon the superficial formations, 

 and rearranging their finer-grained constituents. And it is quite possible that the 

 upper portion of much of the loss of the lower grounds may have been reworked 

 in the same way. But I confess I cannot yet find in the facts adduced by German 

 geologists any evidence of a dry-as-dust epoch having obtained in Europe during 

 any stage of the Pleistocene period. The geographical position of our continent 

 seems to me to forbid the possibility of such climatic conditions, while all the 

 positive evidence we have points rather to humidity than dryness as the prevalent 

 feature of Pleistocene climates. It is obvious, however, that after the flood-waters 

 had disappeared from the low grounds of the Continent, subaerial action would 

 come into play over the wide regions covered by glacial and fluvio-glacial deiosits. 

 Thus, in the course of time these deposits would become modified, — ^just as similar 

 accumulations in these islands have been top-dressed, as it were, and to some extent 

 even rearranged. I am strengthened in these views by the conclusions arrived at 



' Laspeyres : Erl'dutefungen z. geol. Sj)Cinnlkarte v. Preuisen, Sec, Blatt Grbbsig, 

 Zorhig, und Petersbcrg. 



« Klockmann : Jahrh. d. k. prettss. geol. Landcmmtalt fiir 1883, p. 202. 

 • Wahnschaffe : Op. cit. and ZeiUchr. d. devtsch. geol. 6es. 1886, p. 367. 



