EARLY INDIA

9

times. There are no marine sedimentary beds in the
Eastern Himalayas analogous to those of Burma, of the
North-West Himalayas and of the mountains west of the
Indus. These wide highlands, together with the great
plateau of Tibet, were then under sea, subject (so far as
we can tell) to no great earth movements in very early
ages, but undergoing quiet and placid intervals of subsidence
 and upheaval, of alternate existence as open lacustrine
 land surface or sea bottom. At the close of the
jurassic period not only were the North-Western Himalaya
non-existent, but the very rocks of which the ranges to
the west of the Indus are formed were still uncreated.
Only the Aravalli peaks stood lonely and silent overlooking
 a vast north-western sea. Not till the close of
the cretaceous period was India shaken by a series of
eruptive cataclysms into something of its present shape.
A succession of volcanic eruptions, exceeding in force
and grandeur anything that the world has ever seen
(except indeed it be in South America), covered 200,000
square miles of India with lava and tuffs to a depth of
thousands of feet. India must have been for a time one
vast volcanic furnace. This was but the prelude to the
mountain building. Then, at the commencement of the
tertiary period, set in that long succession of earth movements
 which, culminating in intensity about the pliocene
period, are still in perceptible activity, The sea was
driven back; rocks were crushed and forced upwards
until marine limestones were upheaved to 20,000 feet
above sea-level. Then were the sea-formed rocks of the
frans-Indus hills ranged and folded and set in order. It
was the period of the creation of our Indian frontier.}
Geologists have decided that the fossils of Burma
and of the western frontier alike place the formation of
these regions in the eocene, or latter part of the tertiary
Sra. But the great bulk of the North-Western Himalayas
must have been a formidable mountain barrier in times
previous to the eocene period, and, moreover, even in
those early times, the river systems of the Himalayas must
! Oldham, * Evolution of Indian Geography,” vol. iii. ( Journal, R.G.S.).