150 



PROFESSOR ANSTED, ON THE 



direction of the anticlinal axis, and the contortions of the strata near the 

 highest part of the range. The descent on the Western side is rapid 

 but not very long, and brings us quickly to the little town of Vallengy, 

 which is built upon a considerable bed of gravel, the superstratum of 

 a valley, without doubt, of tertiary formation. The valley thus covered 

 up is a fair specimen of many of those occurring between the two most 

 Easterly parallel ranges of the Jura : they are for the most part desolate 

 and barren, now and then watered by a small stream, but then only present- 

 ing a little pleasing scenery close to the water's edge. I should imagine 

 that they had been formed rather by the action of submarine currents 

 depositing gravel, than by any regular subsidence of transported matter 

 in a lake. 



Crossing this valley, whose breadth is here nearly two miles, we come 

 again to the secondary rocks of the Jura, and the road passes over the middle 

 and highest range of those mountains. At a very high elevation, and en- 

 closed between two ridges of nearly 4500 feet, occurs a second small valley, 

 much more narrow and insignificant than the one before mentioned ; and 

 after having crossed it, there is a sudden and rapid descent, leading down to 

 the third and principal valley, that of la Chaux de Fonds, the examination 

 of which was the main object of my excursion. In physical features, as well 

 as geological structure, this valley has all the character of a lacustrine 

 deposit, left dry, either by the silting up of a mountain lake, or gradual 

 evaporation for want of a sufficient supply of water. There is certainly no 

 outlet for water, and scarcely a single running stream in its whole extent. 



The village of la Chaux de Fonds is near the northern extremity of the 

 valley, and about midway between the mountains on the east and west. It 

 is built partly upon a small bed of clay and marl, marked (a) in Section 8, 



SECTION III. ACROSS THE VALLEY OF LA CHAUX DE FONDS. 



Jura. 



Juea. 



If!' 



Level of the Lake of NeucMlel 



Scale 2 inchei to a mile. 



