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INDIA

have been traced very much as they are at present. At
‘he foot of the Himalayas there existed for geologic ages
2 long series of river deposits which have been compressed
and upheaved in very recent times to form what is known
as the Siwalik range, an entirely subsidiary and secondary
-ange of hills which flanks the Himalayas on its southern
face, forming an elevated longitudinal valley between
itself and the foothills of the main system. In the
neighbourhood of those rivers which issue from Himalayan
valleys and cross the elevated valley and the bordering
Siwalik hills there have been found beds of conglomerate
which prove by their composition that rivers large and
rapid, having their sources in the Himalayas or beyond,
must have passed that way from time immemorial very
near to their present channels ; and the evidence of the
rocks connects the origin of these rivers with the pliocene
period. Thus it seems probable that the North-West
Himalayas existed as mountains of very considerable
altitude in pliocene times. Another result of this succession
 of earth movements was the formation of that
great Indo-Gangetic depression which forms one of the
natural geographical divisions of India. The break in
the connection between the Rajmahal and the Assam
hills which gave an opening for the eastward flow of the
Ganges is comparatively recent. Originally the whole
southern flank of the Himalayan system was drained by
the Indus, and the diversion of the Jumna eastward into
the Gangetic basin may be almost historic. Probably
there was an interval, during which the Jumna either
joined the Indus, or found a way south-west through
some of the dry river channels still existing across the
Rajputana desert. The present division of the two
irainage systems, or water parting, is now marked in the
Himalayas by a ridge on which stands the church at
Simla. It is further probable that the same earth movements
 caused the submergence which separated India
from Africa. By the end of the eocene period the west
coast of India was formed, and the only existing evidence
of that old-world connection is now to be seen in the