200 7. H. D. La Touche—Relics of Ice Age in India. 
Tsanpo was shown as flowing on eastwards into the Salween. Now it 
is not at all unlikely that, at the period I have been speaking of, the 
Tsanpo either flowed westwards, as Burrard and Hayden maintain, 
and escaped through the Himalaya at some other point, or lost itself 
in the deserts of Tibet, and that then the Dihang was a mere 
tributary of the Brahmaputra, but that it has since cut back at its 
head into the valley of the Tsanpo and ‘ beheaded’ it. If this was so, 
the Brahmaputra must have been a comparatively small river at that 
time, and it is not surprising that in its lower course it was pushed 
aside by the alluvium brought down by the Ganges and its tributaries. 
Indeed, it may be that the Madhupur Jungle isa relic of the old delta 
face of the Ganges, and that to the east of it, at that time, there was 
open water, reaching perhaps up to the foot of the Khasi Hills; in 
this way I would account for. the backward state of that part of the 
delta. But when the Dihang beheaded the Tsanpo, and brought down 
this enormous accession of water, the Brahmaputra began to assert 
itself. At first it could do little, for the accumulation of alluvium 
in its path was too great to be swept away, and it had to be content 
with its old course into the Meghna; but it had a treacherous ally 
in the Teesta, which had gradually been sapping the defences of 
the Ganges. The Teesta, wandering from side to side over the old 
alluvium south of its exit from the hills, swept it away by degrees, 
wearing down the face of the country to the west of the Madhupur 
Jungle, and in course of time opened a passage for the spill-water of 
the Brahmaputra down the Jennai River. Finally the Teesta, frankly 
deserting its lawful sovereign, the Ganges, threw itself suddenly (this 
happened so recently as 1787) into the Brahmaputra. The effect of 
this was not at first noticeable, but it is probable that the extra silt 
brought down by the Teesta was too much for the Brahmaputra to deal 
with, hampered as it was already by the damming back of its waters 
by the Meghna as the latter slowly raised the levels of Sylhet, and 
that the two allied rivers were compelled to find a new channel. 
The insignificant Jennai offered the means of escape, and its bed was 
occupied about one hundred years ago, 
The struggle that then began between the Brahmaputra and the 
Ganges is still in progress, and issue was joined so recently, almost 
within the memory of men now living, that we cannot suppose that it 
has yet been fought to a finish, or that developments may not take 
place that will have far-reaching effects upon the future history of 
Bengal. The Brahmaputra, being the more powerful river, is not 
likely to rest content with the advantage it has already gained. Up 
to the present time, indeed, it has not been able to exert its full 
strength, for it cannot do so until it has brought the level of the 
Assam Valley to the state in which it would have been had the 
valley been originally excavated by a river of the size and power of 
the present Brahmaputra. As it is, much of the force of the river 
when in flood is spent in the low ground flanking its course; but 
when this has been brought to the true ‘regimen’, there is no doubt 
but that the river will be able to show its real strength with more 
1 Geogr. and Geol. of the Himalaya Mountains, Calcutta, 1907, pt. iii, p, 155. 
