For a
pilgrim, Badrinath the holy town on the bank of the River Alaknanda at
an elevation of 3133 m above mean sea level is the ultimate desire.
Badrinath was established as a pilgrimage site by the Adi Shankaracharya
in the ninth century. More than six lakh people visit annually the
temple for pilgrimage. The broad valley with the temple between the Nar
and Narayan mountains makes a majestic picture.
The valley would have been like one of the usual Himalayan valleys,
narrow with sharp edged mountains on both sides. Call it the will of the
Lord Vishnu or the efforts of the world's best carver, the glacier, the
present landscape was created.
Geomorphological and glaciological studies of the valley have
assumed significance because of the huge annual congregation of
people there. At a place like Badrinath where congregation is large
and naturally vehicular movement is also excessive during pilgrimage
season, media and society are certainly worried about the safety of
the place and the people. In addition the area being in high hazard
zone for earthquakes is always considered vulnerable. Luckily till
date no major mishap has been reported but for a damage by the great
Himalayan earthquake in 1803.
A few months ago media had reported cracks and risk of huge boulders
falling down from Neelkanth Mountain forming the back ground of the
town. However, the studies conducted by Geological Survey Of India
confirmed that such projecting boulders are a common feature in the
Himalayas. P.C. Nawani, Director, GSI supervising the hazard studies
in the area says there is no risk to the holy town because the
Neelkanth Mountain is eight kilometres away. However, the risk from
an earthquake can not be ruled out. The risk from rolling boulders
is apparently less because of the wide valley.
How the temple came up at Badrinath is partly myth and partly
history. However, the carving of a broad valley was due to erosion
by the glaciers. Natural agencies like ice, water and wind are
greatest carvers of a landscape. Amongst these glaciers are one the
most powerful agents that have produced huge deposits of eroded
rocks and rock flour.
Earth scientists from Department of geology, H.N.B. Garhwal
University including H.C. Nainwal, M.Chaudhary, N. Rana, B.D.S. Negi
and R.S. Negi and N. Juyal and A.K. Singhvi of Physical research
laboratory (PRL), Ahmedabad, India joined hands to study and
establish a chronology of glaciation of Badrinath valley. The
findings are significant not merely from academic point of view but
also from the view point of future development of the holy town. It
is certain that in the times to come the number of pilgrims will
continue to swell, thus the town needs special efforts to sustain
the onslaught of the floating population.
Before we ponder upon the chronology of glaciation, we must
understand what are glaciers and how are they formed! Glaciers are
masses of ice which, under the influence of gravity, flow out from
the snowfields where they originate. A snowfield grows whenever a
balance of snow the snowfall is left over to accumulate from year to
year. As the snowfield grows in volume the pressure on the ice that
was formed earliest is sufficient to start the outward flow of the
glacier. The transformation of the snowflakes to glacial ice is a
complex process. End product is a granular aggregate of interlocking
grains, with each grain being a crystal of ice. Each year during
winters the volume of such crystal goes on increasing and a stage
comes when the ice mass starts moving down the slope due to gravity.
As the glacier advances it carves a niche in the valley. The mass of
ice is so much that glacier can be compared to a slow moving
bulldozer, which pulverizes anything underneath to a fine rock flour
and removes chunks of material from sides. Smooth rock surfaces that
escape glacier's wrath develop striations as if clawed by a cat.
Glacier starts losing volume due to melting, evaporation and calving
of ice bergs. This process is called ablation. Maximum ablation
occurs in the summers. Growth of the glaciers in India depends
largely upon the Indian Summer monsoon (ISM), being a major source
of moisture. The valleys carved by the glaciers and the material
left behind them are easy to identify. Thus if it is possible to
date the material it is possible to find out how much was the
glacial cover and in turn establish the patterns of the past
climates.
In a valley glacier like the one that was present where the holy
temple of Badrinath is situated the highest point of lateral
moraines coincides with the Equilibrium Line Altitude and terminates
with at the snout. Thus if it is possible to find out the highest
point of the moraines it is possible to find out the exact
configuration of the glacier including the position of the snout.
Most studies have indicated multiple events of glaciations in the
Himalayas during the last chapter of the earth's history that is
Quaternary period. Usually quantitative estimation of pre-history
events is done with the help of dates obtained from organic
material. In case of inhospitably cold regions of Himalayas it is
difficult to find organic remains of the past. Thus standard
radiocarbon-dating techniques become redundant for such terrains.
Instead Luminescence dating technique has found favors with the
geologists and researchers of past climates.
H.C. Nainwal and his co-workers were able to establish a chronology
of glaciation with the help of cited dating technique. The magnitude
of variability of Quaternary glaciation in Alaknanda valley can be
made out from the piles of moraines. The preserved moraines of the
valley have been grouped in to Alaknanda Stage I, Alkapuri Stage II
and Satopanth Stage III glacial moraines. They observed that the
Stage I glaciation was most extensive and it reached south of
Badrinath up to 3000 metres above mean sea level (m asl), whereas
the Stage II and III were restricted around 3550 and 3700 m asl
respectively.
Nainwal and his team were able to trace the moraines of stage I
glaciation for a distance of around five km downstream of Badrinath
shrine. Being oldest these moraines are less preserved. Lots of
material has been washed by earlier debris avalanches and water
action. However, the linear hummocky ridges covered by birch and
junipers are the remains of what must have been a gigantic glacier.
This is confirmed by near 100 m thickness (opposite bank of Rarang
Chatti) of the stage I moraine material. The production of glacial
flour depends largely on the increment of the ice mass and the
amount of snow melt decides the quantity and grain size of the
material transported. Thus in a regular annual pattern glacial flour
is deposited usually in the pools (glacial lakes) formed downstream
of the snout of the glacier. in layers of finer and coarser material
called Varves. The 100 m thickness of the oldest moraine mostly has
these varves as the evidence of the past glaciation. These indicate
the depth of the lake that must have been present in the valley in
the days of the yore.
Evidences of Stage II glaciation are better preserved. Glacial
action produces a strange admixture of fine clay and huge boulders.
Sometimes one wonders if this is the work of the nature or some
demon! The fine clay is naturally a product of rock grinding at the
floor of the glacier. This powdered mass of clay is deposited over
pre-existing valley configuration. This often acquires shapes of
giant whale shaped mounds called drumlins or 'basket of eggs'.
Nainwal and his colleagues have recorded such drumlins near
Vasudhara.
The Stage III or the youngest moraines (present glaciers) have been
reported by them parallel to the glacier. This moraine starts from
an altitude of 5000 m asl in Bhagirath Kharak glacier and 4700 m asl
in Satopanth glacier and terminates few hundred metres below the
present day snout where it forms a curvilinear ridge.
Armed with this information from the field and samples from well
identified locations, these glaciologists resorted to Optically
Stimulated Luminescence (OSL) dating technique to establish a
chronological succession of glaciation in the valley.
Though, the study requires further refinement in the form of more
data on dates. The results so far are quite amazing. A luminescence
age of 12 Ka has been obtained for the moraine of Stage II located
at 3600 m asl. There is a depression between the moraine and the
terminus of Stage II glacier. This was because when the glacier
started to recede there was a temporary earth movement or some kind
of upheaval. This is further corroborated by the drumlins.
After the last glacial maxima (LGM) that is about 18000 years ago
the Indian Summer Monsoon (ISM) had started to weaken. Lesser
monsoon reduced the extent of the glaciers in these valleys. Taking
a cue from these evidences, Nainwal and his co-workers have
postulated that the Stage I glaciation in the area predates the LGM.
In other words it is older than 18000 years before present.
The Stage III glaciation has given dates of being about 4.5 Ka old.
There is a marked glacial activity evidenced with these dates. The
researchers conclude that between 12 Ka till the onset of Stage III
that is about 4.5 Ka there was a marked reduction in the ISM leading
to reduced glacial activity. The heap of moraine found near the
present snout is believed to have been a product of glaciation some
400 years ago due to the 'Little Ice Age'.
Well this clearly shows that the climatic fluctuations on centennial
scale matter more than annual fluctuations. Global warming is
inevitable the climatologists foresee. But the past evidences have
always shown that after a warming there is always a cold phase.
What is alarming is the rapid 'development' of Badrinath valley. As
evidenced the glacial material that is present to a depth of 100 m
in the valley is not a very stable material. It is incorrect to
permit many structures and also multistoried structures without
conducting proper geotechnical and geo-seismic studies. There is a
clear cut evidence of a prehistoric lake that existed in the
vicinity of the Helipad at Badrinath. Such lake sediments can get
compacted/disturbed due to vibrations and cause local damages. A
detailed knowledge of the glacial history of Alaknanda valley will
be certainly useful while making further development plans.
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For a
pilgrim, Badrinath the holy town on the bank of the River Alaknanda at
an elevation of 3133 m above mean sea level is the ultimate desire.
Badrinath was established as a pilgrimage site by the Adi Shankaracharya
in the ninth century. More than six lakh people visit annually the
temple for pilgrimage. The broad valley with the temple between the Nar
and Narayan mountains makes a majestic picture.