Task Force Report - Govind Ballabh Pant Institute of Himalayan ...

Asia convergence (20 mm/year) is absorbed by a
thrusting along the southern front of the Himalaya
leading to the continuous rising of the Himalaya
Box 1 - Origin of the Himalaya and
ongoing processes
The Himalaya came into existence as a result of a
collision along the convergent boundary between
the Indian Plate and the Eurasian Plate. The
collision began in the Upper Cretaceous period
(about 70 million years ago) when the Indian
Plate, moving north at about 15 cm/year, collided
with the Eurasian Plate. By about 50 million years
ago this movement completely closed the Tethys
Sea thrusting the sediments up and forming the
youngest and loftiest mountain ranges on the face
of the earth known as the Himalaya. The Indian
plate is still moving at 67 mm/year, and over the
next 10 million years is likely to travel about 1,500
km into Asia.
by about 5 mm/year and, therefore, making it
geologically unstable and prone to earthquakes
8,9,10
. Being the youngest and loftiest mountain
chain (more than 30 peaks exceeding 7,600 m in
elevation 11 ) of the world which is still rising, the
Himalayan region is naturally unstable and fragile.
Physiographically, starting from the Siwalik hills in
the south, the Himalayan mountain range extends
to the Tibetan plateau in the north. The broad
divisions are the Siwaliks, the lesser Himalaya,
the greater Himalaya and the trans-Himalaya;
extending almost uninterrupted throughout its
length, separated by major geological fault lines.
The climate ranges from tropical at the base of the
mountains to permanent ice and snow at the highest
elevations. The amount of yearly rainfall increases
from west to east along the base of the range. The
Indian Himalayan region (IHR) contains some of
the wettest spots on the face of the earth in the
eastern side, and vast expanses of cold desert in the
north-west. The eastern Himalayan region, which
is at a relatively lower latitude than the western
region, is also comparatively warmer. Local relief
and location determine such climatic variation not
only in different parts of the Himalaya but even on
different slopes of the same range. The diversity
in climate, altitude, rainfall and soil types along
the altitudes and longitudes manifests itself in the
presence of a variety of agro-climatic zones, each
harbouring distinct and sometimes overlapping
plant and animal communities.
The higher regions of the Himalaya are snowbound
throughout the year and in spite of their proximity
to the tropics, the perpetual snow level seldom
falls below 5,500 meters. The Himalayan ranges
encompass numerous glaciers (9,575 12 ); notable
among them is the Siachen which is the largest
glacier in the world outside the polar region (Table
1.1). The Himalayan glaciers are the source for
several large perennial rivers which in turn further
define and shape the mountain configuration, and
drain into major river systems of the continent
(Table 1.1).
The Himalayan region is dotted with hundreds of
small and big, crystal clear lakes, many of which
are considered sacred by the followers of various
religions. Most of such lakes are found at altitudes
less than 5,000 m above mean sea level (amsl).
The Pangong Tso which is spread across the border
between India and Tibet (China) at an altitude of
4,600 m amsl is the largest (as wide as 8 km at places
and nearly 134 km long) lake in the region. The
other notable high altitude lakes are Gurudogmar
(5,148 m) and Tsongmo in Sikkim, and Tilicho in
Nepal.
The Himalayan ranges have a profound affect on
the climate of the Indian subcontinent and the
Tibetan plateau. They prevent frigid and dry arctic
winds from blowing south into the subcontinent
keeping South Asia much warmer when compared
to the regions located between corresponding
latitudes throughout the globe. They are a barrier
for the moisture laden monsoon winds, preventing
them from traveling further northwards and thus
facilitating timely and heavy precipitation in the
entire Northern India.
8 Valdiya, K. S. 2001, Current Science, 81(11):1418-1431.
9 Valdiya, K. S. 2002, Physical Geography, 26(3):360-399.
10 Valdiya, K. S.1993, Current Science, 64(11-12):835-885.
11 Gurung, H. 2005. Atlas of the Himalaya. ICIMOD, Kathmandu, Nepal.
12 Raina, V.K. & Srivastava, D.K. 2008. Glacier Atlas of India. Geological Society of India, Bangalore.
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Report of the Task Force