Chota Nagpur Plateau


The Chhota Nagpur Plateau is a plateau in eastern India, which covers much of Jharkhand state as well as adjacent parts of Odisha, West Bengal and Chhattisgarh. The Indo-Gangetic plain lies to the north and east of the plateau, and the basin of the Mahanadi River lies to the south. The total area of the Chota Nagpur Plateau is approximately.

Etymology

The name Nagpur is probably taken from Nagavanshis, who ruled in this part of the country. छोटा Chhota is also the name of a village in the outskirts of Ranchi, which has the remains of an old fort belonging to the Nagavanshis.

Formation

The Chhota Nagpur Plateau is a continental plateau—an extensive area of land thrust above the general land. The plateau has been formed by continental uplift from forces acting deep inside the earth. The Gondwana substrates attest to the plateau's ancient origin. It is part of the Deccan Plate, which broke free from the southern continent during the Cretaceous to embark on a 50-million-year journey that was interrupted by the collision with the Eurasian continent. The northeastern part of the Deccan Plateau, where this ecoregion sits, was the first area of contact with Eurasia.

Divisions

The Chhota Nagpur Plateau consists of three steps. The highest step is in the western part of the plateau, where pats, as a plateau is locally called, are above sea level. The highest point is. The next part contains larger portions of the old Ranchi and Hazaribagh districts and some parts of old Palamu district, before these were broken up into smaller administrative units. The general height is. The topography in undulating with prominent gneissic hills, often dome-like in outline. The lowest step of the plateau is at an average level of around. It covers the old Manbhum and Singhbhum districts. High hills are a striking part of this section - Parasnath Hills rise to a height of and Dalma Hills to. The large plateau is subdivided into several small plateaux or sub plateaux.

Pat region

The western plateau with an average elevation of above mean sea level merges into the plateau of the Surguja district of Chhattisgarh. The flat topped plateau, locally known as pats are characterized by level surface and accordance of their summit levels shows they are part of one large plateau. Examples include Netarhat Pat, Jamira Pat, Khamar Pat, Rudni Pat and others. The area is also referred to as Western Ranchi Plateau. It is believed to be composed of Deccan basalt lava.

Ranchi Plateau

The Ranchi Plateau is the largest part of the Chhota Nagpur Plateau. The elevation of the plateau surface in this part is about and gradually slopes down towards south-east into the hilly and undulating region of Singhbhum. The plateau is highly dissected. The Damodar River originates here and flows through a rift valley. To the north it is separated from the Hazaribagh plateau by the Damodar trough. To the west is a group of plateaux called pat.
There are many waterfalls at the edges of the Ranchi plateau where rivers coming from over the plateau surface form waterfalls when they descend through the precipitous escarpments of the plateau and enter the area of significantly lower elevation. The North Karo River has formed the high Pheruaghaugh Falls at the southern margin of the Ranchi plateau. Such falls are called scarp falls. Hundru Falls on the Subarnarekha River near Ranchi, Dassam Falls on the Kanchi River, east of Ranchi, Sadni Falls on the Sankh River are examples of scarp falls. Sometimes waterfalls of various dimensions are formed when tributary streams join the master stream from great heights forming hanging valleys. At Rajrappa, the Bhera River coming over from the Ranchi Plateau hangs above the Damodar River at its point of confluence with the latter. The Jonha Falls is another example of this category of falls. The Gunga River hangs over its master stream, the Raru River and forms the said falls.

Hazaribagh plateau

The Hazaribagh plateau is often subdivided into two parts – the higher plateau and the lower plateau. Here the higher plateau is referred to as Hazaribagh plateau and the lower plateau as Koderma plateau. The Hazaribagh plateau on which Hazaribagh town is built is about east by west and north by south with an average elevation of. The north-eastern and southern faces are mostly abrupt; but to the west it narrows and descends slowly in the neighbourhood of Simaria and Jabra where it curves to the south and connects with the Ranchi Plateau through Tori pargana. It is generally separated from the Ranchi plateau by the Damodar trough.
The western portion of Hazaribagh plateau constitutes a broad watershed between the Damodar drainage on the south and the Lilajan and Mohana rivers on the north. The highest hills in this area are called after the villages of Kasiatu, Hesatu and Hudu, and rise fronting the south above the general level of the plateau. Further east along the southern face a long spur projects right up to the Damodar river where it ends in Aswa Pahar, elevation. At the south-eastern corner of the plateau is Jilinga Hill at. Mahabar Jarimo at and Barsot at stand in isolation to the east, and on the north-west edge of the plateau Sendraili at and Mahuda at are the most prominent features. Isolated on the plateau, in the neighbourhood of Hazaribagh town are four hills of which the highest Chendwar rises to. On all sides it has an exceedingly abrupt scarp, modified only on the south-east. In the south it falls almost sheer in a swoop of to the bed of Bokaro River, below Jilinga Hill. Seen from the north the edge of this plateau has the appearance of a range of hills, at the foot of which runs the Grand Trunk Road and NH 2.

Koderma plateau

The Koderma plateau is also referred to as the Hazaribagh lower plateau or as the Chauparan-Koderma-Girighi sub-plateau.
The northern face of the Koderma plateau, elevated above the plains of Bihar, has the appearance of a range of hills, but in reality it is the edge of a plateau, from the level of the Gaya plain. Eastward this northern edge forms a well-defined watershed between heads of the tributaries of Gaya and those of the Barakar River, which traverses the Koderma and Giridih districts in an easterly direction. The slope of this plateau to the east is uniform and gentle and is continued past the river, which bears to the south-east, into the Santhal Parganas and gradually disappears in the lower plains of Bengal. The western boundary of the plateau is formed by the deep bed of the Lilajan River.The southern boundary consists of the face of the higher plateau, as far as its eastern extremity, where for some distance a low and undistinguished watershed runs eastward to the western spurs of Parasnath Hills. The drainage to the south of this low line passes by the Jamunia River to the Damodar.

Damodar trough

The Damodar basin forms a trough between the Ranchi and Hazaribagh plateaux resulting from enormous fractures at their present edges, which caused the land between to sink to a great depth and incidentally preserved from denudation by the Karanpura, Ramgarh and Bokaro coalfields. The northern boundary of the Damodar valley is steep as far as the south eastern corner of the Hazaribagh plateau. On the south of the trough the Damodar keeps close to the edge of the Ranchi plateau till it has passed Ramgarh, after which a turn to the north-east leaves on the right hand a wide and level valley on which the Subarnarekha begins to intrude, south of Gola till the Singhpur Hills divert it to the south. Further to the east the Damodar River passes tamely into the Manbhum sector of lowest step of the Chotanagpur plateau.

Palamu

The Palamu division generally lies at a lower height than the surrounding areas of Chota Nagpur Plateau. On the east the Ranchi plateau intrudes into the division and the southern part of the division merges with the Pat region. On the west are the Surguja highlands of Chhattishgarh and Sonbhadra district of Uttar Pradesh. The Son River touches the north-western corner of the division and then forms the state boundary for about. The general system of the area is a series of parallel ranges of hills running east and west through which the North Koel River passes. The hills in the south are the highest in the area, and the picturesque and isolated cup-like Chhechhari valley is surrounded by lofty hills on every side. Lodh Falls drops from a height of from these hills, making it the highest waterfall on the Chota Nagpur Plateau. Netarhat and Pakripat plateaux are physiographically part of the Pat region.

Manbhum-Singhbhum

In the lowest step of the Chota Nagpur Plateau, the Manbhum area covers the present Purulia district in West Bengal, and Dhanbad district and parts of Bokaro district in Jharkhand, and the Singhbhum area broadly covers Kolhan division of Jharkhand. The Manbhum area has a general elevation of about and it consists of undulating land with scattered hills – Baghmundi and Ajodhya range, Panchakot and the hills around Jhalda are the prominent ones. Adjacent Bankura district of West Bengal has been described as the “connecting link between the plains of Bengal on the east and Chota Nagpur plateau on the west.” The same could be said of the Asansol and Durgapur subdivisions of Bardhaman district.
The Singhbhum area contains much more hilly and broken country. The whole of the western part is a mass of hill ranges rising to in the south-west. Jamshedpur sits on an open plateau, above mean sea level, with a higher plateau to the south of it. The eastern part is mostly hilly, though near the borders of West Bengal it flattens out into an alluvial plain. In the Singhbhum area, there are hills alternating with valleys, steep mountains, deep forests on the mountain slopes, and, in the river basins, some stretches of comparatively level or undulating country. The centre of the area consists of an upland plateau enclosed by hill ranges. This strip, extending from the Subarnarekha River on the east to the Angarbira range to the west of Chaibasa, is a very fertile area. Saranda forest is reputed to have the best Sal forests in Asia.

Climate

The Chhota Nagpur Plateau has an attractive climate. For five to six months of the year, from October onward the days are sunny and bracing. The mean temperature in December is. The nights are cool and temperatures in winter may drop below freezing point in many places. In April and May the day temperature may cross but it is very dry and not sultry as in the adjacent plains. The rainy season is pleasant. The Chota Nagpur Plateau receives an annual average rainfall of around, which is less than the rainforested areas of much of India and almost all of it in the monsoon months between June and August.

Ecology

The Chhota Nagpur dry deciduous forests, a tropical and subtropical dry broadleaf forests ecoregion, encompasses the plateau. The ecoregion has an area of, covering most of Jharkhand state and adjacent portions of Odisha, West Bengal, Bihar, Chhattisgarh, Uttar Pradesh, and Madhya Pradesh.
The ecoregion is drier than surrounding ones, including the Eastern Highlands moist deciduous forests that covers the Eastern Ghats and Satpura Range to the south, and the Lower Gangetic Plains moist deciduous forests in the lowlands to the east and north.
The plateau is covered with a variety of various habitats of which Sal forest is predominant. The plateau is home to the Palamau Tiger Reserve and other large blocks of natural habitat which are among the few remaining refuges left in India for large populations of tiger and Asian elephants.
Forests range from dry to wet and reach up to tall. The plateau is also swampy in some places and in other parts is covered with bamboo grasslands and shrubs such as Holarrhena and Dodonaea. The flora of the plateau is distinct from the wetter parts of India that surround it and includes a number of endemic plants such as Aglaia haslettiana and endangered plant species including Madhuca longifolia and Butea monosperma.
Tigers, Asian elephants, four-horned antelope, blackbuck, chinkara, dhole wild dog and sloth bear are some of the animals found here while birds include the threatened lesser florican, Indian grey hornbill and other hornbills.
More than half of the natural forest on the plateau has been cleared for grazing land and the scale of the mining operations on the plateau is disturbing to the movement and therefore the survival of wildlife including elephants and tigers.

Protected areas

About 6 percent of the ecoregion's area is within protected areas, comprising in 1997. The largest are Palamau Tiger Reserve and Sanjay National Park.
Chhota Nagpur plateau is a store house of mineral resources such as mica, bauxite, copper, limestone, iron ore and coal. The Damodar valley is rich in coal and it is considered as the prime centre of coking coal in the country. Massive coal deposits are found in the central basin spreading over. The important coalfields in the basin are Jharia, Raniganj, West Bokaro, East Bokaro, Ramgarh, South Karanpura and North Karanpura.