1919.] History of the Drainage of Northern India. 93 
bedded clays, attaining a thickness of some 5,000 feet north of 
the Salt Range. They certainly occur in Jammu and on the 
Sutlej and no doubt in all intermediate areas but are much less 
Jpper Siwaliks, consisting of pale-coloured, coarse- 
grained Seciilons:, with abundant but scattered pebbles 
attain their maximum thickness between the Chenab and the 
Sutlej, where it may amount to as much as 15,000 f 
Beyond ‘the eastward border of Nepal it seems exceedingly 
likely that nearly the whole of the Siwalik series belongs | to 
this horizon. Here a thickness of some 11,000 feet is probably 
within the mark, ee it can be little less in the Abor hills. 
They are less thick in the Salt Range where an average of 
5,000 feet is fairly near the correct figure. 
South of the Salt Range they are known to occur in vari- 
ous places, but I am unable to give actual “cee of the thick- 
ness except in the Marri. hills and Sind where 2,000 feet pro- 
ably represents their total thickness. 
I have already given an estimate as to how much of this 
from sige to place consists of boulder-conglomerates. 
ma, the Irawaddi series does not appear to have 
begun cata the Middle Siwalik epoch. The writer has seen 
no clear evidence of the occurrence in it of Upper Siwalik 
fossils, though it is possible that strata of this age may exist 
in the lower portion of the Irawaddi valley. Pebbly and con- 
cretionary beds—so-called Red Beds—occur at its base and 
coarse sandstones and clays for the remainder. A few thin 
freshwater horizons occur at lower levels interbedded with 
marine or estuarine beds of the Pegu series. 
he Siwaliks of Cutch and Katthiawar, including Perim 
Island, are, probably, largely Middle Siwalik and it is unlikely 
that much either = Lower or Upper Siwalik age is contain 
in them. They may be mere ip ony of a seed larger basin — 
ym 
of deposit, now kerio beneath the se 
shall now proceed to eeiainia ‘these facts into a con- 
nected history on the assumption of a great Siwalik river 
flowing westward and north-westward on which chains eon 
alone, so far as the writer can see, can the character and dis 
tribution of the deposits be explain 
Such a river might in Eocene times have entered the sea 
somewhere near Subathu, following somewhat the same course 
as the modern Ganges and rising on a watershed, of which a 
portion may, doubtless, still be seen in the Raj mahal and 
. 
