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PROF. EDWARD HULL, M.A., LL.D., F.R.S., 



5. Measurement of the thickness of the glacier at its maximum. — The 

 Belle Vue moraine, as I understand, is situated at the corner above 

 Treib, and must represent, one would say, the remains of the left 

 hand lateral moraine of the old glacier as it made this sharp turn to 

 the westward. This may possibly represent an excessive upper 

 datum line, since the extra pressure of the ice at this point might 

 tend to lift the left lateral moraine somewhat above the mean 

 level of the. glacier; otherwise there can be no doubt as to the 

 thickness of the ice at this point being fully 2,000 feet. 



6. The general limit of the erratic blocks. — This being about 1,400 

 feet above the lake, if we add the depth of the lake, the sum fairly 

 well represents the thickness of the glacier. As to the nature of 

 the boulders, one would naturally expect to find the granitoid gneiss 

 of St. Gothard which is in a direct line, but any granite coming 

 from the Finsteraarhorn itself must have made a long detour by 

 way of the Furka pass and the Urseren thai across the Aar valley 

 in the first instance. 



7. The barrier of^^ the two mysterious Mythen." — It is an open question 

 whether the glacier did or did not follow a route previously 

 indicated in pre-glacial times. There can be very little doubt that 

 the original valley of the Keuss passed northwards by way of 

 Brunnen, Schwyz and the ^geri sea. The mysterious Mythens 

 form a mountain mass which prevented both river and glacier from 

 extending to the eastward, but it is doubtful if this mountain mass 

 had any other effect on the old Reuss drainage. The origin of the 

 middle part of the Lake of Lucerne is obviously very difficult to 

 explain, hence the precise cause of the deflection of the Eeuss 

 drainage to the westward instead of to the northward is not quite 

 clear. But I suggest that the transverse valley of the Reuss found 

 its way into a valley which was partly longitudinal (geotectonic) 

 and partly transverse, and which now constitutes the middle section 

 of the Lake of Lucerne. 



As regards the two " mysterious My then " themselves, they are 

 represented by Schmidt as a mass of Jurassic rock resting 

 on the usual Eocene of the district. Since there are no Jurassic 

 rocks in the immediate neighbourhood, their appearance in this 

 attitude seems to have astonished even the Swiss geologists 

 themselves, accustomed as they are to the most unexpected 

 inversions. 



