468 PLIOCENE GLACIO-FLUVIATILE CONGLOMERATES IN [ Aug. 1902, 
was Deckenschotter, as it was said to be when he saw it, this must 
be so. In any case, he was disposed to look upon the formation of 
the actual lake-basin of Zurich as a yet later phenomenon than the 
second glaciation, for he did not see how the gravels below the 
town could be formed, if the lake existed, unless they were all 
attributed to the Sihl, which he thought improbable. The amount 
of zonal subsidence required by the Author, though large, was 
not impossible, but it meant that the valley-systems above the 
lake would be higher than their present elevation by 1300 feet, 
and probably more. They proceed, however, from a rather low 
part of the Alps, and this elevation-hypothesis explains some 
difficulties—among others, the change from excavating to filling-up 
the main valleys like those of the Limmat and Rhine. He thought 
it probable that this paper, which abandoned one very important 
position taken up in the former one, might require modification in 
the future; but it was, nevertheless, valuable as supplying an 
explanation of some very perplexing problems. 
The Rev. Epw1n Hutt also regretted the Author’s absence. He 
would have lked to learn his views on the age of the diversion of 
the Sihl channel from the Lake of Zurich, as to which his former 
paper gave such interesting particulars. 
Mr. H. W. Monckton said that he had some hesitation in 
criticizing a paper of which he had only heard a comparatively 
short abstract. He considered the Deckenschotter of the Uetli- 
berg, alluded to by the previous speakers, a very difficult deposit to 
explain. ‘The underlying glacial bed seemed to show the presence 
of large glaciers, and he thought it possible that the Deckenschotter 
itself might be more or less of glacial origin, and suggested the 
possibility that the valley of the Lake of Zurich might have been 
full of ice at the time of its deposition. 
Prof. SoLttas enquired whether some of the difficulties of the 
Author’s explanation might not be met on the supposition that the 
Lake of Zurich and the Valley of the Limmat were already in 
existence before the deposition of the Deckenschotter, but filled 
with ice during ‘this deposition. The presence of ‘ grundmorine ’ 
below the Deckenschotter pointed to the existence of a considerable 
body of ice, the intra- and infra-morainic material of which would 
become converted, as the ice melted away, into pebbles. ‘The esker- 
material, as seen in Ireland, showed that large quantities of rounded 
pebbles might be formed during the melting of glaciers and betore 
their final disappearance. 4 
Prof. Bonney, in reply to a request from the President, said that 
as, when he had visited a country, he retained in his memory what 
he had seen better than what he had read, he could not undertake 
to say at the moment how far the Author was in accordance with, 
or differed from, the Swiss geologists. In regard to remarks which 
had been made, he said that he did not think that the ‘ first moraine’ 
required the ice to have been thick above it, and that the Decken- 
schotter had but little resemblance to the materials of an esker. 
It was true fluviatile gravel, not at all unlike that now filling 
