of mountain
building

[1] To those unacquainted with the terminology of Indian geology
the following list of approximate equivalents in time will be of
use

Ngari Khorsum Beds - Pleistocene.
Siwalik Series - Miocene and Pliocene.
Sirmur Series - Oligocene.
Kampa System - Eocene and Cretaceous.
Lilang System - Triassic.
Kuling System - Permian.
Gondwana System - Carboniferous.
Kenawar System - Carboniferous and Devonian
Muth System - Silurian.
Haimanta System - Mid. and Lower Cambrian.
Purana Group - Algonkian.
Vaikrita System - Archaean.
Daling Series - Archaean.

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on a large scale in the Himalayan area till the Tertiary
upheaval, it is, in the majority of cases, literally correct to
speak of the mountains as having their generations like organic
beings, and passing through all the stages of birth, life, death
and reproduction. The Alps, the Jura, the Pyrenees, the Andes,
have been remade more than once in the course of geological time,
the _debris_ of a worn-out range being again uplifted in succeeding
ages.

Thus to dwell for a moment on one case only: that of the
Pyrenees. The Pyrenees arose as a range of older Palmozoic rocks
in Devonian times. These early mountains, however, were
sufficiently worn out and depressed by Carboniferous times to
receive the deposits of that age laid down on the up-turned edges
of the older rocks. And to Carboniferous succeeded Permian,
Triassic, Jurassic and Lower Cretaceous sediments all laid down
in conformable sequence. There was then fresh disturbance and
upheaval followed by denudation, and these mountains, in turn,
became worn out and depressed beneath the ocean so that Upper
Greensand rocks were laid down unconforrnably on all beneath. To
these now succeeded Upper Chalk, sediments of Danian age, and so
on, till Eocene times, when the tale was completed and the
existing ranges rose from the sea. Today we find the folded
Nummulitic strata of Eocene age uplifted 11,000 feet, or within
200 feet of the greatest heights of the Pyrenees. And so they
stand awaiting

140

the time when once again they shall "fall into the portion of
outworn faces."[1]

Only mountains can beget mountains. Great accumulations of
sediment are a necessary condition for the localisation of
crust-flexure. The earliest mountains arose as purely igneous or
volcanic elevations, but the generations of the hills soon
originated in the