Chota Nagpur Plateau
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.
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 3,000 feet (910 m) - 3,500 feet (1,100 m) above sea level. The highest point is 3,819 feet (1,164 m). 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 2,000 feet (610 m). The topography in undulating with prominent gneissic hills, often dome-like in outline. The lowest step of the plateu is at an average level of around 1,000 feet (300 m). It covers the old Manbhum and Singhbhum districts. High hills are a striking part of this section - Parasnath Hills rise to a height of 4,480 feet (1,370 m) and Dalma Hills to 3,407 feet (1,038 m).The large plateau is subdivided into several small plateaux or sub plateaux.
The western higher plateau with an average elevation of 1,000 metres (3,300 ft) above mean sea level merges into the plateau of Chhattishgarh. 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.The area is also referred to as Western Ranchi Plateau. It is believed to be composed of Deccan lava.
It is the largest part of the Chota Nagpur Plateau. The elevation of the plateau land in this part is about 700 metres (2,300 ft) above mean sea level. The general topography is undulating. The Ranchi plateau gradually slopes down towards south-east into the hilly and undulating region of Singhbhum (ealier Singhbhum district or what is now Kolhan division). The plateau is highly dissected. 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 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 height. The North Karo River has formed a 17 metres (56 ft) high Pheruaghaugh Falls at the southern margin of Ranchi plateau. Such falls are called scarp falls. Hundru Falls (75 m) on Subarnarekha River near Ranchi, Dassam Falls (39.62 m) on Kanchi River, east of Ranchi, Sadni Falls (60 m) on Sankh River (Ranchi plateau) are examples of scarp falls. Sometimes waterfalls of various dimensions are formed when tributary streams join the master stream from great height forming hanging valleys. At Rajrappa (10 m), 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 (25.9 m) is another example of this category of falls. In fact the Gunga River hangs over its master stream, Raru River (to the east of Ranchi city) and forms the said falls.
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. Hazaribagh plateau on which Hazaribagh town is built is about 40 miles (64 km) east by west and 15 miles (24 km) north by south with an average elevation of 2,000 feet (610 m). 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 600 ft 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 (2,465 ft). At the south-eastern corner of the plateau is Jilinga Hill (3,057 ft). Mahabar Jarimo (2,185 ft) and Barsot (2,180 ft) stand in isolation to the east, and on the north-west edge of the plateau Sendraili (2,210 ft) and Mahuda (2,409 ft) 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 2, 810 ft. 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 2,200 feet 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 (on the Koderma plateau) runs Grand Trunk Road / NH 2.
Koderma plateau is also referred to as the Hazaribagh lower plateauor 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, 800 ft 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 runs east ward to the western spurs of Parasnath Hills. The drainage to the south of this low line passes by the Jamunia River to the Damodar.
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. 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 division generally lies at a lower height than the surrounding areas of Chota Nagpur Plateau. On the east Ranchi plateau intrudes into the division and the southern part of the division merges with the Pat region. On the west are Surguja highlands of Chhattishgarh and Sonbhadra district of Uttar Pradesh. Son River touches the north-western corner of the division and then forms the state boundary for about 45 miles (72 km). 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 143 metres (469 ft) from these hills, making it the highest waterfall on Chota Nagpur Plateau. Netarhat and Pakripat plateaux are physiographically part of the Pat region.
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 1,000 feet (300 m) and it consists of undulating land with scattered hills – Baghmundi and Ajodhya range, Pachakot 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 3,000 feet (910 m) in the south-west. Jamshedpur sits on an open plateau, 400 feet (120 m) to 800 feet (240 m) 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.
Chota Nagpur plateau is a store house of minerals like 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 2,883 sq.km. The important coalfields in the basin are Jharia, Raniganj, West Bokaro, East Bokaro, Ramgarh, South Karanpura and North Karanpura.