* 
470 Reports and Proceedings—Biitish Association— 
example, has been led by his observations on the glacial formations 
of the Inn Valley to recant his former views, and to become a 
formidable advocate of the very theory which he formerly opposed. 
To his work and the memoirs by Penck, Briickner, and Bohm 
already cited, and especially to the admirable chapter on glacier- 
erosion by the last-named author, I would refer those who may be 
anxious to know the last word on this much-debated question. 
The evidence of inter-Glacial conditions within the Alpine lands 
continues to increase. These are represented by alluvial deposits 
of silt, sand, gravel, conglomerate, breccia, and lignites. Penck, 
Bohm, and Brickner find evidence of two inter-Glacial epochs, and 
maintain that there have been three distinct and separate epochs of 
glaciation in the Alps. No mere temporary retreat and re-advance 
of the glaciers, according to them, will account for the phenomena 
presented by the inter-Glacial deposits and associated morainic accu- 
mulations. During inter-Glacial times the glaciers disappeared from 
the lower valleys of the Alps—the climate was temperate, and 
probably the snow-fields and glaciers approximated in extent to those 
of the present day. All the evidence conspires to show that an 
inter-Glacial epoch was of prolonged duration. Dr. Briickner has 
observed that the moraines of the last. Glacial epoch rest here and 
there upon léss, and he confirms Penck’s observations in South 
Bavaria that this remarkable formation never overlies the morainic 
accumulations of the latest Glacial epoch. According to Penck and 
Brickner, therefore, the léss is of inter-Glacial age. There can be 
little doubt, however, that léss does not belong to any one particular 
horizon. Wahnschaffe! and others have shown that throughout 
wide areas in North Germany it is the equivalent in age of the 
‘Upper Diluvium,’ while Schumacher ® points out that in the Rhine 
valley it occurs on two separate and distinct horizons. Prof. Andrez 
has likewise shown ° that there is an upper and lower loss in Alsace, 
each characterized by its own special fauna. 
There is still considerable difference of opinion as to the mode of 
formation of this remarkable accumulation. By many it is considered 
to be an aqueous deposit ; others, following Richthofen, are of opinion 
that it is a wind-blown accumulation; while some incline to the 
belief that it is partly 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 léss, we find this attributed to the action of heavy rains washing 
over and rearranging 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 
1 Abhandl. z. geol. Specialkarte v. Preussen, etc., bd. vii. heft 1 ; Zeitschr. d. 
deutsch, geol. Gesellsch., 1885, p. 204; 18%6, p. 367. 
2 Hygienische Topographie von Strassburg i. F., 1885. 
3 Abhandl. z. geol. Specialkarte v. Elsass-Lothringen, bd. vii., heft 2. 
4 Laspeyres : Erlauterungen z. geol. Specialkarte y. Preussen, etc., Blatt Grobzig, 
Zorbig, und, Petersberg. 
