Vol. 60.] LAKE-BASINS BETWEEN TEE JURA AND THE Airs. 67 



Deckenschotter nor the Zurich gravels (and the same was true else- 

 where) could have been formed in the neighbourhood of a glacier. 

 He had always attributed the Alpine lakes to zonal bending, and had 

 long thought that there were at least two lines on the north side ; 

 but he was inclined to believe that there might have been slight 

 subsidence along the watershed of the Alps, as the higher parts of 

 the Alpine Rhine and Rhone valleys seemed now to be filling up. 



Prof. Garwood, in reply to a question asked by the Author, stated 

 that he did not think that the Fairhaven glaciers in Spitsbergen, 

 quoted by Martins, affected the point at issue : the observation 

 probably referred to an overhanging advance of the upper layers of 

 the ice, so common in that district ; and he could hardly believe that 

 any of the Swiss geologists seriously suggested that a glacier could 

 traverse a large lake-basin in the manner indicated by the Author, 

 by clinging merely by its borders, and pass through unsupported in 

 the middle. He was interested to hear that the Author attributed 

 the formation of these large Swiss lakes to a time posterior to the 

 maximum glaciation of the Alps, on the strength of the fluviatile 

 character of the deposits described from their lower end ; but, what he 

 would specially like to know, was the age of the valleys in which the 

 lakes occurred. A similar problem of the origin of the Italian lakes 

 had occupied his attention for some years, and he did not think that a 

 local subsidence could alone account for these lakes on the south side 

 of the Alps. The Lake of Como was an especially difficult problem, 

 as it not only ran at right angles both to the axis of the Alps and the 

 strike of the limestones, but also exhibited a reversed drainage of a 

 very peculiar character. Why did the drainage flow from Como to 

 Lecco ? What river or glacier-system could be pointed to at the 

 present day, which, after flowing as a trunk-stream, divided into two 

 deep branches, as must have been the case if the present drainage 

 of the Lake of Como represented the original direction of flow of the 

 valleys? It had often occurred to him that the rivers might once 

 have flowed northward, and not southward. It was a curious fact 

 that so many of the lake-branches came in from the south ; and 

 Lugano, which is 100 feet higher than Como, might very easily have 

 entered as a tributary of the latter lake at Menaggio. The difficulty 

 in the way was the range of the Spliigen Alps. Mr. Marr had once 

 suggested that this uplift might have taken place since the formation 

 of the old valley-systems now occupied by the lakes : this would throw 

 back the date of these valleys to Miocene times. He had collected 

 for some time from the deposits of the Righi district with this idea 

 in his mind, but without any definite result. The more, however, 

 that he saw of the district, the more was he convinced of the great 

 age of the valleys, and the probability of the reversal of the original 

 direction of their drainage. He thought that the many areas of 

 special subsidence required by the Author for all the Swiss lakes 

 would require some definite proof in each case. He was glad to 

 find that the Author did not include direct glacial erosion among 

 the possible modes of origin for the lakes ; although it must be 

 remembered that quite recently an eminent American geologist had 



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