1919.] History of the Drainage of Northern India. 95 
slowly and brought down less material. The character of the 
Nahan cpp bears witness to the probability of this 
suppositi 
Buikiward of the dam the flow of the river must have be- 
me more normal, that is more rapid and so in spite of the 
still rising Salt Range the Lower Siwalik sediments of this area 
would be less in amount than, and differ in character from, the 
Nahans of the Himalayan area, which is actually the case. It 
is possible, as the writer has suggested elsewhere, that the sand- 
stone bands of the Chinji beds interbedded with concretionary 
clays represent periods of flooding alternating with cessation 
therefrom in a river valley w hose | gradient was fairly constant 
and sp agen to that of the modern Ganges and Brahma- 
putra. The successive changes would be due to variations in 
the rate of uplift both behind and in front of the depositing 
area. 
t the close of the Lower Siwalik period, however, the 
Nahar sediments must have mt ae their basin while the 
Salt piel and the Himalayas as evidenced by the argillaceous 
and concretionary character of the beds which succeeded the 
Lower Siwaliks of the latter area at Haritalyangar and else- 
where and which are not to be distinguished from those of the 
Chinji and Nagri zones of the Salt Range. 
n Middle Siwalik times the elevation of the Salt Range 
must begs ve been more rapid to account for the greatly ee 
sedimentation in that area, which diminishes in amount as 
go eon up the course of the 
the Pliocene further sbeation ‘of the Kashmir-Jammu 
area ae have occurred to cause the accumulation of the vast 
Upper Siwalik deposits. The main river valley must now have 
coinci with the outcrop of the Upper Siwaliks, as shown on 
the map, in Pl. II, Fig. 2, completely dominating the old southern 
tributaries. At the same time the whole course of the river. 
must have become flatter, with the result that Upper Siwalik 
sediments are met with all along its valley. 
In the last stage of the Siwalik period the upheaving forces 
were intensified, and as a consequence of this the whole area 
embraced by Jammu and Kangra appears to have been prac- 
tically turned into a large Jake with an outlet on the western 
side. The numerous tributaries from the now lofty mountains 
They, therefore, must have accumulated to form a boulder 
deposit, generally distributed over the whole of the area in 
question, though varying in thickness from place to place. 
y a minimum could have passed over the western edge and 
been available to paces ont to the boulder conglomerates of 
