350 DISTRIBUTION OF BOULDER STONES. 



able phenomenon. These loose blocks already occur in 

 the alpine valleys, which open into the great valley, be- 

 tween the Alps and the Jura. They are found more 

 abundantly in the wide parts of valleys immediately be- 

 low the narrow or contracted passes, and few occur in the 

 narrow, steep, and rocky parts of the valleys. 



Loose blocks are found, at a greater or less height, in 

 the smaller lateral valleys that open into the transverse 

 alpine valleys, which terminate in the great valley between 

 the Alps and the Jura. If these lateral valleys form pas- 

 Fes (which lead over into other valleys by a lowering of 

 the high mountain chain), which are not more than 4000 

 feet above the level of the sea, loose blocks occur, not 

 only in these passes, but also more or less widely distri- 

 buted in the opposite valleys. In the great principal val- 

 ley which stretches between the Alps and the Jura, from 

 the Lake of Geneva to beyond the Lake Constance, we 

 find these loose blocks dispersed over all the hills whose 

 elevation is not more than 3000 feet above the level of 

 the sea ; but even here the distribution of the blocks is 

 not entirely irregular. The largest are found on such 

 hills and acclivities as are opposite the mouths of the al- 

 pine valleys, in the great principal valley. The blocks 

 are frequently found higher on such acclivities, than on 

 the sides of those valleys which may be considered as a 

 continuation of the alpine valleys. The loose blocks are 

 found every where on that acclivity of the Jura range 

 which is opposite to the Alps, and they are found highest 

 and largest in those places which are directly opposite the 

 mouths of the alpine valleys. In such places, the blocks 

 again attain an elevation of nearly 4000 feet above the 

 level of the sea; whereas, in the intermediate places, 



