1856.] Report of the Magnetic Survey of India. 123 



the form of the valleys themselves, that most of the large transverse 

 valleys of the Himalayas have been excavated to a depth of more 

 than 3,000 and 4,000 E. feet by the action of water alone. 



20th. "We noticed also the absence of true erratic blocks both in 

 the Himalayas and in Thibet, which are so numerous round the 

 Alps of Europe. 



Glaciers. 



21st. Glaciers sometimes of great extent are found everywhere 

 in the Himalayas round the central groups. They even exist in 

 Thibet, where the fall of snow is so much less, and we have every 

 reason to believe, both from what we saw ourselves, and from the 

 information which we received, that glaciers are again met with in 

 the ranges to the North and North-east of the Indus. 



The two largest glaciers which we have been able to examine, are 

 the glacier of Milum and the Ibi Gamin glacier, issuing from Ibi 

 Gamin into Thibet and giving origin to the Mangnang river. These 

 two glaciers are certainly larger than any in the Alps, but, as a 

 general rule, we may say, that the glaciers of the Himalayas are 

 not so much larger as we might expect from a consideration of the 

 great extent and elevation of these mountains. One cause of this 

 phenomenon may be, that the high valleys of the Himalaya have, 

 in general, a greater and more precipitous slope than the corres- 

 ponding valleys in the Alps, so that the ice is carried down too 

 quickly to lower and warmer places ; the heavy rains during the 

 warmest part of the year, will also tend to melt away the ice. 



22nd. — During the course of our journey, we visited and examined, 

 to some extent, more than 40 glaciers, which, according to the classi- 

 fication in the Alps, must be termed glaciers of the first order. The 

 largest accumulation of great glaciers in the Himalayas of Kumaou, 

 Gurhwal and Bisser, is around the great group of the Ibi Gamin 

 peaks. 



The physical structure of the glaciers of the Himalayas, the laws 

 of motion, the distribution of the moraiues and of the crevasses, 

 is precisely the same as in the glaciers of the Alps. We could 

 constantly trace also the blue bands of ice, or " ogives" which form 

 such a characteristic physical phenomenon in the Alpine glaciers. 



B 2 



