1856.] Beport of the Magnetic Survey of India. 119 



apparent stratification prevails. Our observations have perfectly- 

 convinced us that this is no real stratification, but merely cleavage, 

 produced, as is now generally assumed, by a great tension in the 

 interior of the highly altered rocks. 



The general dip of the cleavage planes is in a Northerly direction, 

 deviating in some parts of the mountains to the North-west, and in 

 others to the North-east ; and it seems that in many cases at least 

 the cleavage of the central gneiss masses dips in the same direction 

 North North-east, or North North-west. 



If, after crossing the central groups we continue a geological 

 section into Thibet, we observe that, in the sedimentary fossiliferous 

 strata which are then met with, there occur, independently of each 

 other — (a) a true stratification and (b) a cleavage, which dips in the 

 same direction, like the cleavage of the crystalline rocks which un- 

 derlie the sedimentary strata. 



15th. This very general Northerly dip of the cleavage continues 

 in the sedimentary formations until we reach the alluvial plain of 

 the Sutlej valley. But it is a fact well worthy of remark, that a 

 perfect change in the dip of the cleavage takes place in the moun- 

 tain ranges which rise between the Sutlej and the Indus, and to the 

 North-east of the Indus. 



We had occasion to examine these mountains along two sections 

 over the Chako La and Phoko La Passes, distant more than 20 miles 

 from each other, in a North-westerly direction. The mountains are 

 composed of various metamorphic schists, intersected with green- 

 stone dykes, running on an average parallel with the mean direction 

 of the chain. * 



In these mountains, as well as in the similar rocks brought to 

 light by the great denudation of the Sutlej river, we constantly found 

 the cleavage dipping under angles of 45° to 70° to the South or 

 South-west. 



This dip is exactly opposite to the dip of the cleavage in the 

 Himalayas. 



It therefore seems that, talcing a general view, the cleavage in the 

 Himalayas of Kumaon, and in the mountain ranges which face the 

 Himalaya to the Northward, forms one great fan, of enormous dimen- 

 sions, the cleavage dipping in the Southern part of this fan to the 



