Himalaya Mountain is a result of
formation of tectonic forces and it is a process of two continental collisions.
This great mountain modify by weather and erosion continuous process. Himalaya
– Tibet region is identifying as an Asia visible water tank. It supplies fresh
water for one-fifth of the world population.
Formation
of Himalaya
The Indian subcontinent pushes
towards to north in the late Precambrian and Paleozoic period. Himalaya known
as a young – folded mountains if compare with Appalachian old mountains which
located in America. Himalaya formation is take places in recent earth history.
Theory of Himalaya formation is started to develop in 1912 with Alfred Wegner
continental drift theory. According to his theory earth joint by giant tectonic
plates and today continents are formed from one single land mass and it called
as “Pangaea”. Continents are drifted apart from each another due to tectonic activity
from this land mass and formed today continents and oceans that we know today.
Around 200 million years ago the
middle era of Precambrian there was a region with an extensive sea stretched
presently occupied by Himalaya region. Eurasian north landmass known as Lorezia
and South Indian land mass called as Gondwana. These two land masses were
divided by Tethys Sea. During this period super continent Pangaea land mass
began to split into different land masses and start to move various directions.
The Indian plate breaks off from the Pangaea and move northwards toward
Eurasian plate. As a result shallow Tethys Sea gets deposited by large amount
of sediments. The two land masses Eurasian and Indian sub-continent come to
close each other. Indian plate was move 16 cm per year (6 inch per year).
The initial mountain building
process started around 70 million years ago. During this period these land
masses get collide and depart from another. As a result Tethys Sea began to
fold folded and raised their shallow valleys. Next 65 million years ago second
mountain building process started and Tethys sea bed again began to rise. The
Sea get backward and sea bed start to elevated with higher mountain ranges.
Later 25 million years ago,
formation of lower Shivalik mountain ranges start the next phase of mountain
building and periodic mountain building phases occurred. Indian plate pushed
against the Eurasian plate and raise the Himalayan ranges further.
Function
of Himalaya
Himalaya still raising it
elevation in small rate after passed it uplift phase. Indian continent
continually move toward to north in the rate of 2cm per year. As a result
Himalaya is raising it elevation in the rate of 5mm per year. This show the
Himalaya is geologically activity and it unstable structure.
Beneath the Himalaya the earth
crust is 60-780 km thicker and this thicker crust formed crustal root to go
downward into the mantle and it is an important process for mountain building.
Because buoyancy of the root allows the high reaches of the mountain.
The Himalaya continues to raise
it massive weight bear up by crust which located beneath the mountain and it
buried into earth crust. If this rock pressed down into mantle, it will start
to melt and began to follow slowly. This process creates mountain collapse
lower. Several scientists believed this stress cause large earth quakes in this
region and there was recorded of severe earth quake incidences. Recent earth
quake occurred in Nepal-Himalaya region on April 2015 and it cause large impact
in those areas and millions of people get affected.
Biodiversity
of Himalaya region
Himalaya region is an
accommodation for richness of biodiversity. It is a hotspot for hundreds of
specific species and wild animals. Hindu kush – Himalaya (HKH) region is known
as a living place for large number of ecosystems in the world. It extends more
than 3500m and includes variety of ecosystems. Varied altitude, climate
conditions, geography-biophysical conditions and soil formation are contributed
for this region biodiversity richness.
Himalaya Mountain ranges are
divided as a complex geology structure. It contains snowcapped peaks, large
snow valleys, deep river gorges and high variety of plants. Complex climate
conditions, geology process, usage of resources and economic status are the
main reason for resource degradation and environment consequences in Himalaya
region (jodha, 2001).
Rodgers (1988) divided the
Himalaya regions as a 5 biotic provinces under the biogeography zones:
Trans Himalayas, North West
Himalayas, West Himalayas, Central Himalayas and Eastern Himalayas.
Western Himalaya bio zone is a
cool and include vegetation cover that opposed to dry conditions. Conifers,
legumes and grasses are dominant plants in this region. Eastern Himalaya zone
is composites of sub-tropical wet vegetation cover and include magno lias,
oaks, laurels, epiphytes, orchids, and fens are seen as a high rate.
These biogeography zones are reflecting
variety of ecosystems and include cool desert. North ranges of Himalaya
represent cool desert ecosystems and it temperature is below -75oC
and this region annually getting 500-800 mm rainfall. This desert occupied with
4500-6000 feet high plateau and it described as a Himalaya transitional
biogeography zone by Rodgers & Pawar (1988). This zone extent along to
Tibet plateau the origin place for Hindu, Sutlej, Brammaputhra and Yangtze
rivers and it invade 2.6 billion square kilometer region.
Himalaya region is the
accommodation for large number of plant species. It include all kind of plants
such as, the tropical wet ever green plants to sol forests, marshes, swamps
which are belongs to deciduous wet plant species, mix deciduous forests,
sub-tropical coniferous forest, Broad leafed temperature forests, temperature
wet broad leafed deciduous forests, temperature conifer forests, sub alpine,
Alpine plants, Alpine grasses and Alpine savanna.
It occupied with snow leopards,
Himalayan brown bear, red banda, Himalayan Lynx, Kahmir stag, Himalayan Musk
Deer, Yak, Himalayan Ibex, Himalayan thar and Himalayan Beared vulture wild
animals. Vertebrates and invertebrates animals also consider as important wild
animals.
Threats
of Biodiversity
Richness biodiversity of Himalaya
region expect a sever threats and becoming endangers. Deforestation, over
exploitation of resources, filling of wetland drainage system, settlements,
fragmentation of lands, population growth is the main reasons for biodiversity
loss. Plant species are becoming threats by deforestation, agricultural
activities, river valley projects, industry, and urbanization activities (MOEE
1999).
Agro- pastoral is the main reason
for resource degradation. Most part of the people in this region depends on
agro – pastoral activities. Over grazing activity leads to insufficient food
supply and cause spread of diseases, decline in egg products to wild animals.
Hunting by wild animals is the main problem for domestic animals.
Natural disasters and wild fire
are other reasons for biodiversity loss. Habitat destruction and fragmentation
cause pressure in laying eggs and high mortality. Construction of dams and
infrastructure facility, transport systems activities also contribute for
habitat fragmentation and of destruction of biodiversity. Hunting wild animals
and illegal commercial activities are increasing the risk for species of
Himalayan region. Himalayan plants, musk deer, Himalayan black bear,
butterflies and Tibetan antelopes are having a high value in international
market.
Indian government takes many
steps to prevent these activities and promote to protect the Himalayan region
and its biodiversity. Such as protected area networks-biological reserves,
national parks and sanctuary and sign in multilateral environment agreements
(CITES, CBD……).
Although high rate of arrivals,
population pressures, economic development and concomitant excessive
utilization of the regions resources are being induce the threats for Himalaya
ecosystem and its habitat.
Himalaya
region and climate change
Tibet plateau is a vulnerable place
to reflect the world climate conditions. Glacier covers 104,850 km2 of
areas. This region Temperature rising 0.3oC per decade and this rate
double the world average and glacier reduce by 7% per year.
Uplift of Himalaya-Tibet plateau
cause effects on region and global climate. Estimation shows that Himalaya
uplift and climate impacts on Tibet plateau are enhanced the winter and summer
monsoons and increase the drought in Central Asia. This trend helps to created
Gobi and Mongolian desert and cause dust particles. These dust particles are
carried by westerly from the east part of the desert to china and there
deposited as a sediment on lands and ocean.
Himalaya ranges occupied with 37,000km2
of ice sheet covers and include more than 15,000 ice sheets. These are annually
supplies great amount of fresh water and therefore called as an “Asia water
tank” (Dyurgerov and Maer, 1997). Ice sheets include 17% of mountain regions,
and other 30-40% is seen as a season snow cover.
This Asia water tank supplies
fresh water for more than 100 million of population due to dry seasons and provide
water for Asian large seven rivers; Ganga, Hindu, Brahmaputra, Salween, Mekong,
Yankizen and Guwango. These river valleys are accommodation for 1.3 billion of
populations.
The longest ice sheet of
Gangothri which located in Central Himalaya disappearing 3 times faster than
last decade. This was 29 km long and 2-6 km width. Lose of this ice sheet cause
shortage of water in many rivers and create economic, environment problems for
west china, Nepal, Pakistan and North Indian people. Lose of ice sheets reduce
the July-September monsoon flow by 2/3 and increase the water shortage for 500
million of population and 37% of Indian agricultural lands.
Nepal-Himalaya glacier ecosystems
got impact by climate change in last several decades and also Nepal consider as
a one of the vulnerable country for climate change.
Dust particles that collected in
eastern china seen as a climate records and these are evidence for uplift
period and sediments are 8 million years old. Himalaya ranges prevent the
precipitation and humidity for Gobi and Mangolian deserts around 8 million years
and turn to South and East Tibet plateau.
Himalaya region ice sheets
decline very fast than other parts of the world ice sheets (IPCC). Annually
10-60 m of Himalayan ice sheets are disappearing and if this lose rate continue
80% of the ice sheet will disappear in 2025.
References :
(1) THE
HIMALAYA MOUNTAINS THEIR AGE, ORIGIN AND SUB- CRUSTAL RELATIONS
authored by D. N. WADIA published in 1965
(2)
http://library.thinkquest.org/10131/geology.html
(3)
Michael Allaby, Dr. Robert R. Coenraads, Dr. Stephen Hutchinson, Karen McGhee,
Dr. John O'Byrne, Dr. Ken Rubin (2008): The
Encyclopedia of Earth, Sydney.
