178 KHASI HILLS. 



from the stream, thick coarse rushy grasses luxuriate. When the water 

 rises it naturally forces its way through these when they act completely as 

 a filter. I have many times seen water so turbid that it might almost 

 have been called mud, in which great clouds of su.9pended matter were 

 floated along, overflowing such banks, and rushing out at the other 

 side into the general flat of the jheels, 'perfectly clear, though dark in 

 colour : the breadth of the bank not being more than 3 feet ! It is not 

 surprising,, therefore, that these banks should continue steadily to rise. In 

 this way also, the striking contrast between the clear, dark coloured water 

 of the jheels, and the muddy turbid streams is readily accounted for. 



The great difference in the physical features of the Northern and 

 Southern portion of these hills, has been described above ; atid the 

 coincident change in the geological structure of these two portions' 

 But, in addition to this change, it must be remembered as mate- 

 rially influencing the general result that the fall of rain within these 

 hills, and even at no greater distance than twenty miles to the North 

 of the Station, is little more than one-half of the amount which falls at 

 Cherra Poonjee, and along the outer scarp of the hills, where the rain- 

 charged-clouds which pass Northwards from the Bay of Bengal, and 

 over the flat country intervening, first meet the hills, and are suddenly 

 cooled down and deprived of their moisture. The different force also 

 with which the sea would act along the Southern scarp of these hills 

 exposed to the wide sweep of the Indian Ocean, and along the North- 

 ern, where its forces would be confined and limited by the long bay- 

 like indentation of the valley of Assam, has been very justly insisted 

 on by Dr. Hooker, (a) as, to a great extent, accounting for the difference 

 in character of the two escarpments. 



These instances will sufiice to show the rapid degradation which is 

 now progressing in these hills, and to prove that, however inadequate 

 they might at first appear, the ordinary atmospheric forces under the 



(a) Himalayan Journals, Vol. IL, page 324. 



