Prof. A. C. Ramsay on the Glacial Theory of Lake- Basins. 295 



before depression began, mnst have been 28,000 or 30,000 feet 

 high during the greatest extension of the glaciers. If we make 

 an allowance for denudation, of course the Alps were still higher. 

 Depress the central ridge h till it attains the height of a, the 

 axis of movement or hinge being at d, and the triangle ged, 

 previously filled with ice, would assume the position of the triangle 

 bed; and when the glacier melted, the hollow became filled with 

 water*. This is asking a good deal; and if it were necessary to ac- 

 count for the greater snowfall of the old glacier-epoch in the Alps 

 by increased height of the mountains, which it is not, though we 

 might be inclined to grant Charpentier his 3000 feet, the diffi- 

 culty increases when we are asked to grant an elevation five 

 times as much ; nor indeed is the question likely to be raised 

 by any one who measures his angles and calculates his numbers. 

 If we remove the point where the angular movement ceased out 

 into the alluvial plain of the Po, the difficulty simply increases 

 for every yard we carry it in that direction ; and a little reflec- 

 tion will show that at no great distance the angular movement 

 necessary to drain the lake would raise the Central Alps to a 

 height of 60,000 instead of 30,000 feetf. 



Neither have we any special reason to suppose that any of those 

 oscillatory movements have frequently taken place in the Alps, 

 such as are common accompaniments of earthquakes in volcanic 

 areas ; and the trifling instances Sir Charles gives of these in 

 Cook's Strait, and of another gradual movement in Finmark of 

 135 feet, though they have some relation to the subject, yet 

 cease to have any probable significance when we consider the 

 magnitude of the movement needed in our case, and also that 

 it is not only necessary to apply it for the formation of the rock- 

 bound lake-basins of the Alps, but also to numerous other cases 

 on the flanks of many mountain-chains, and not there alone, 

 but to the widely glaciated undulations of North America. Has 

 Dr. Julius Haast also been mistaken when, adopting generally 

 my views, he accounts for the excavation of the rock-bound lake- 

 basins of New Zealand by glaciers ? or was there a central depres- 



* For the sake of simplicity, I make no allowance for curvature, which 

 would be very small even if the problem were reduced to extreme ac- 

 curacy. To attempt this would be merely pedantic. 



f If, however, we are seriously asked to grant the probability of such 

 movements having taken place in the Alps at a geological period so late, it 

 is difficult to see why Sir Charles Lyell should object to Professor Heer's 

 hypothesis, that Europe and America were joined across the Atlantic when 

 the Miocene flora grew in Europe. The depth of the Atlantic is not so 

 great but it would be easy to (♦arry a line across it in soundings not greater 

 than the oscillations of level I have indicated the Alps are required to have 

 undergone during and since glacial times. If any one can grant this for 

 times so recent, it is easier to grant it for times so old as the Miocene epoch. 



