Chota Nagpur Plateau : Origin, Climate , Ecology.

 Introduction :- 

The Chota Nagpur Plateau is a plateau in eastern India, which covers much of Jharkhand state as well as adjacent parts of Odisha, West Bengal, Bihar 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 65,000 square kilometres.

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

Formation:-

The Chota 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 violently interrupted by the northern Eurasian continent. The northeastern part of the Deccan Plateau, where this ecoregion sits, was the first area of contact with Eurasia.

Analysis of the Plateau :-

The Chota 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 910 to 1,070 metres (3,000 to 3,500 ft) above sea level. The highest point is 1,164 metres (3,819 ft). 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 610 metres (2,000 ft).

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 300 metres (1,000 ft). It covers the old Manbhum and Singhbhum districts.

The large plateau is subdivided into several small plateaux or sub plateaux.

• Pat region:- The western plateau with an average elevation of 1,000 metres (3,300 ft) above mean sea level merges into the plateau of Surguja district of Chhattisgarh. The flat topped plateaux, locally known as pats are characterized by level surface and accordance of their summit levels shows they are part of one large plateau.
• Ranchi plateau :- It is the largest part of the Chota Nagpur Plateau. The elevation of the plateau land in this part is about 700 m (2,300 ft) and gradually slopes down towards south-east into the hilly and undulating region of Singhbhum (earlier Singhbhum district or what is now Kolhan division.
• 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 64 km (40 mi) east by west and 24 km (15 mi) north by south with an average elevation of 610 m (2,000 ft).
• 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 the Karanpura, Ramgarh and Bokaro coalfields.

Climate :-

The Chota 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 23 °C (73 °F). 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 38 °C (100 °F) but it is very dry and not sultry as in the adjacent plains. The rainy season (June to September) is pleasant.The Chota Nagpur Plateau receives an annual average rainfall of around 1,400 millimetres (55 in), which is less than the rainforested areas of much of India and almost all of it in the monsoon months between June and August.

The Chota Nagpur dry deciduous forests, a tropical and subtropical dry broadleaf forests ecoregion, encompasses the plateau. The ecoregion has an area of 122,100 square kilometres (47,100 sq mi), covering most of Jharkhand state and adjacent portions of Odisha, West Bengal, Bihar, Chhattisgarh, Uttar Pradesh, and Madhya Pradesh

By: Shashank Shekhar