Prof. Struder on Bowlders. 331 



We can avoid a part of these difficult questions, if we assume 

 with HH. Agassiz and Schimpfer a general ice-covering of the 

 earth, a freezing of the water in seas, lakes and streams from the 

 poles to the equator. On the frozen inland sea, which thus in 

 part overspread Switzerland, the Alpine fragments might have 

 been slid to the Jura and to the slopes of the outjutting molasse 

 hills, and in the same manner the Swedish blocks could have 

 been shoved across the Baltic. The sudden occurrence of this 

 ice-epoch was the cause of the destruction of the antediluvian 

 animal races and vegetable species, of which not a single sort has 

 survived to our time : and thus even in the earlier geological 

 epochs, the periods of heat and life have been interrupted by pe- 

 riods of freezing and death. This originally Indian view of na- 

 ture is capable of taking a very poetical form ; and Hr. Schimp- 

 fer has given us a specimen of it. It looses, moreover, with the 

 sword of Alexander to be sure, several of the most ravelled knots 

 in Geology and Paleontology, but to make it harmonize with 

 facts and with the prose of physical investigations, is a problem 

 which far surpasses at least my powers , — the striking relations 

 between the dispersion of the blocks and the shape of the val- 

 lies, which must ever lie at the foundation of any satisfactory 

 theory, are left in the one lately proposed unregarded and unex- 

 plained. We see not how the blocks could have alighted, as they 

 often have done in great numbers, behind outjutting hills, or 

 pressed in upon the sides of the vallies ; why, farther, their zone 

 rises so high on the Jura opposite the Rhone-valley, and then to- 

 wards Soleure gradually sinks down till it reaches the present 

 valley-bottom ; wherefore in the narrows of the vallies, the blocks 

 are altogether wanting, while on the contrary in the wide portions 

 they occur in the greatest number. But still more difficult is it 

 to see from whence this periodical freezing, this alternation of 

 heat and cold, of life and death, could have been derived. Not 

 from a change of internal heat, for we know from Fourier, that at 

 present, the influence of the internal heat upon the temperature 

 of the surface scarcely amounts to ■^\'^ c. The warmth in which 

 we live, and which remains constant at different depths of the 

 ground according to latitude, and also agrees with the mean an- 

 nual warmth of the atmosphere, is almost exclusively an effect of 

 the sun. We might accordingly be referred to a periodical change 

 in the intensity of solar heat, — a problem, with which Herschel 



