1855.] SHARPE— ELEVATION OF THE ALPS. 113 



2. Pr^rayean at the head of the Valtelline, which I did not visit, 

 stands at 6593 feet. 



3. The valleys of the Rhone, the Engadine, and Oberhalbstein 

 end between 5750 and 5900 feet. 



4. Many valleys end between 5300 and 5450 feet. 



5. The lower Engadine ends abruptly at Zernetz at 4910 feet; 

 and several others between 4750 and 4900 feet : these nearly corre- 

 spond to the lower line of erosion, placed at 4800 feet. 



6. Between 3800 and 4400 feet there are so many heights noted, 

 that it is difficult to throw them into groups ; but the most distinct 

 are at about 3900, 4100, and 4400 feet. 



7. In Oberhalbstein there is a termination of the lower valley at 

 3600 feet. 



8. Val Blegno ends above Olivone at about 2900 feet. 



9. Linththal and Muottathal end between 2500 and 2600 feet. 

 Thus it appears that the earlier elevation of the Alps, represented 



by the higher water-levels, was in great starts of 1000 feet or more 

 at once ; that these gradually became less and less violent, until, 

 after rising above the well-marked line of 4800 feet, the later eleva- 

 tions were so gradual that the rough process by which it is here 

 attempted to measure them is hardly sufficient to distinguish one of 

 the lower levels from another. 



The valleys above mentioned are excavated in rocks of every age 

 from the nageliluh to the gneiss ; therefore the operations here de- 

 scribed were all posterior to the eocene period. I am unable to say 

 whether they are prior or posterior to the formation of the molasse ; 

 but I think it probable that they were posterior, and that the only 

 deposit which was formed during the last elevation of the Alps was 

 the drift. 



Terraces of Alluvium in the Alpine Valleys, 



The valleys of the Alps offer innumerable instances of terraces of 

 alluvial matter projecting from their sides and cut through, often to 

 a great depth, by the present streams. These occur in places where 

 it is impossible to account for their existence without going back to 

 causes operating under different circumstances from those which now 

 exist ; for the forces now at work are destroying and carrying them 

 away. Such terraces are common in all mountainous regions, and they 

 have everywhere nearly the same character, form, and constitution : 

 their materials consist of sand and gravel, of various degrees of coarse- 

 ness, mixed up with slightly worn fragments of rock, all or nearly 

 all belonging to the rocks to be found in the same valley, and 

 arranged with an irregular approach to stratification, which slopes 

 both down the valley and from the sides towards the middle of the 

 valley at angles varying from 2° to 15°, in planes usually parallel to 

 the surface of the terrace. 



The nature of these deposits is so precisely similar to those formed 

 immediately below the surface of the water wherever a mountain- 

 stream enters a lake or a quiet arm of the sea, that this explanation 



