*i92 M. Renoir on the Glaciers of the Vosges 



wards the plain, and the debris of calcareous rocks are never 

 found ascending,^^ 



Now, I had myself long since remarked, that the ancient 

 alluvium or terrain de comhlement of the southern declivity, 

 which descends the mountains, following likewise the slopes of 

 the valleys in the directions north, south, north-west, and south- 

 east, is exclusively composed of the debris of the superior 

 rocks, without ever presenting specimens of calcareous rocks 

 before reaching the level of the latter. From this I am like- 

 wise entitled to conclude, that these debris have been carried 

 along by a current coming from the north-ivest parallel to the 

 general direction of our valleys^ since no calcareous fragment 

 has ascended. 



Here, then, are two currents directly opposite to each other, 

 descending from the same point of the Vosges, the source of 

 which we must consider as having been at the summit, a sup- 

 position incomprehensible, and altogether inadmissible. 



All these difficulties disappear, and every thing admits of a 

 natural explanation, if we place on the heights (ballons) of 

 Giromagny and Servance, and on the neighbouring elevations, 

 glaciers, which, by their continual movement, would transport, 

 without effort, all the fragments of rocks detached from the 

 summits, and the melting of which would furnish, for a long 

 period, torrents and powerful rivers, conveying to a distance 

 from both sides of the ridge of the chain all the substances 

 which we now call ancient alluvium. 



All the other great valleys of the Vosges affording grounds 

 for similar observations, it is easy to perceive that in these 

 mountains, as in the Alps, boulders and rolled pebbles extend 

 in a fan-shaped form all round the system, which could never 

 be the effect of a current. 



Thus, then, as appears to me, the existence of ancient gla- 

 ciers on the Vosges mountains is established, and yet we know 

 that the height of Giromagny, the culminating point of those 

 we are considering, does not exceed 1250 metres. 



If this phenomenon of cooling belongs to the earth, has its 

 temperature, at one time, been capable of sinking to such 

 a degree ? Or have the valleys, at some period or other, 



