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Barail Range of Assam | UPSC | North East India Info

The Barail Range is a group of mountains or high ridges and watersheds between the Brahmaputra and Barak rivers. The terrain ranges from flat and undulating in the river valleys, to mountainous with steep slopes. Located in Dima Hasao district of Assam a state of India (Latitude: 25° 16' 27" N - Longitude: 93° 20' 51" E)

Geography of Barail Range

The Barail range is a tertiary mountain range topographically bridging the Archaean Meghalaya Plateau with the tertiary Naga Hills which is the south-western projection of the Himalayas.

The Barail hills of Assam covering the N.C Hills district are the westward continuation of the Barail range stretching from Tuensang across Nagaland.

The Barail range divides the N.C Hills into two parts-the northern part falling under the Brahmaputra basin and the southern part falling under the Barak basin.

The range rising from 300 m in the southern part of Karbi plateau attains a maximum height of 1866 m in the Theipibung peak of N.C Hills district.

The other notable peaks of the Barail range are the Hemeolowa (1679 m), the Mahadeo (1739m), the Kaukaha (1736m) and the Tukbai (965m) peaks. The southern range of the Barail range is steeper than the northern face due to faulting.

The north-flowing rivers like Kopili and Dhansiri and their headstreams had dissected the range by their headward erosion and thus have subdued the northern face to lower elevations with gentle slopes.[1] 

Barail Range map

The Barail Range is another important mountain range in Nagaland, It enters the State from North Cachar district of Assam and after passing through Kohima area runs towards the north of Kohima. Japvo, which is located a few kilometers south of Kohima is the highest peak of Barail Kange. 

It attains a height of 3,014 meters above mean sea level, here the range is met by a complex hilly range prolonged from the Arakan Yoma (the dominant mountain system of Burma}, and from the is point the main range runs in a north and northeasterly direction. 

The Barail Range is connected with the Patkai Range through small ranges. One of these ranges connects them in the vicinity of Kohima. Up to Mao (Manipur) it runs in a south-east direction and from there the range assumes an eastward trend and runs for a few kilometers until it follows s a southward direction. [5]

Geology of Barail Range

The Barails are grey to brownish color sandstone of fine to coarse grain size. The term Barail was first coined by Evans (1932). They are usually alternations of shale and sandstone giving rise to typical turbidite character.[2]

The main rock types found in the Barail Group are well-bedded sandstone, shale, clay and coal. The Barail rocks are followed by an unconformity over which Miocene Surma Group of rocks are deposited.

The Barails are mainly confined to the ’Belt of Schuppen' in the outer hill areas and also crop out as outliers over Disangs in some high ridges in the intermediate hill areas. The main rock types found in the Barail Group are well-bedded sandstone, shale, clay, and coal.

The Barail rocks are followed by an unconformity over which Miocene Surma Group of rocks are deposited. The Surmas are exclusively confined to the 'Belt of Schuppen' and are also molassic sediments of sandstone, shale, and clay.

The Tpam Group of rocks which conformably overlie the Surmas are mainly confined to the 'Belt of Schuppen', though they also occur sporadically in the eastern high hill areas where they unconformable overlie the Disangs. [6]

The end of the Eocene is marked by the swallowing of the geosyncline and the formation of second-order troughs and geanticlines. In these rhythmically sinking shallow basins, the argillaceous-arenaceous Barail Group of sediments were deposited. Intermittent sub-aerial conditions led to the formation of the at presently exploited coal seams within this Group.

An equivalent of this Group is also seen in the plateau. The end of the Oligocene was marked by the emergence of the Barail Group of sediments, (present North Cachar Hills) and most parts of the Upper Assam platform. Corollary to this dynamism, certain local basins were also formed wherein the argillaceous-arenaceous Surma Group of sediments were deposited.

In this period there developed tensional and compressional tectonism which may be earmarked as pre-and-post Barail. The Belt of Schuppen is a product of post-Barail tectonism. The Upper Miocene was marked by the upliftment of the Naga-Patkai-Lushai Hills and the Eastern Himalayas with paripassu sinking of the foredeep and the intermittent troughs where the Tipam Group of sediments was deposited.

During Mio-Pliocene times, further upliftment of the Shillong Plateau against the Dauki Fault resulted in the unconformable deposition of the Dupitila rocks Intermittent reactivation of some criss-cross faults in the platform towards the end of Miocene led to the activation of the Naga-Patkai ranges in the east.

This led to the formation of shallow lacustrine and fluviatile basins where the Dihing Group of rocks were deposited. Intense orogeny and rapid sinking of the beds led to the pebbly nature of the Dihing rocks Unconformabiy overlying the Dihing rocks are the Quaternary alluviums in the name of Bhanger and Khader which represents the final stage of Himalayan orogeny.[3]

Dima-Hasao lake

Biodiversity of Barail Range

The Barail Range forms one of the most diverse, but lesser-known, ecosystems of the region. The great altitudinal variations (from less than 100 m to towering peaks of more than 1,900 m) and the resultant diversity of vegetation, coupled with a rich faunistic composition makes the area an ideal choice for a wildlife reserve and an IBA. The Barail is the highest hill range in Assam.

It includes the North Cachar Hill Reserve Forest (RF) of Cachar district, Barail RF of Cachar and North Cachar Hills districts and the unclassified forests stretching from the Simleng river valley in the west to Laike in the east (in North Cachar Hills district).

The high bird’s diversity of the Barails was documented long ago The only known population of Blyth’s Tragopan Tragopan blythii in Assam is in the extreme east of the Barails near Laike. The only known breeding site of the Cinereus Vulture Aegypius monarch tenuirostris in Assam was also in the Barails.

The Lesser Adjutant Leptoptilos javanicus is seen in the southern valleys, while there are past records of the Swamp Francolin Francolinus gularis from the southwestern fringe (Choudhury 2000). The site covers two biomes: Biome-8 (Sino-Himalayan Subtropical Forests) at c. 1,000 to 2,000 m and Biome-9 (Indo- Chinese Tropical Moist Forest) mainly below c. 1,000 m. BirdLife International (undated) has listed 95 species in Biome-8, of which nine are found here.

Two out of nine species listed in Biome-9 are also present. Both are quite common in the Tropical Moist Forests. As can be expected, some species of other biomes are also found, mainly as winter migrants.

The Barail Range has rich mammalian fauna. Seven species of primates are found, these are: Slow Loris Nycticebus coucang, Stump-tailed Macaque Macaca arctoides, Assamese Macaque M. assamensis, Rhesus Macaque M. mulatta, Pigtailed Macaque M. nemestrina, Capped Langur Trachypithecus pileatus and Hoolock Gibbon Hylobates hoolock.

Other mammals include the Asiatic Black Bear Ursus thibetanus, Tiger Panthera tigris, Leopard P. pardus, Clouded Leopard Neofelis nebulosa, Jungle Cat Felis chaus, Leopard Cat Prionailurus bengalensis, Golden Cat Catopuma temminckii, Marbled Cat Pardofelis marmorata, Wild Dog Cuon alpinus, Sambar Cervus unicolor, Muntjak Deer Muntiacus muntjak, Wild Boar Sus scrofa, Binturong Arctictis binturong and the Serow Nemorhaedus sumatraensis. Small populations of Gaur Bos frontalis also occur. Asian Elephant Elephas maximus is locally extinct now.

Common reptiles include various species of lizards and snakes throughout the site. The Brown Hill Tortoise Manouria emys is also met with occasionally.[4]

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