The North-eastern Plateau: Meghalaya and Karbi Anglong

Detail

What the North-eastern Plateau is

• The north-eastern plateau is a piece of the Peninsular plateau (the old, hard, stable block of rock that forms south and central India) that now lies cut off in north-east India.

• Its two main parts are the Meghalaya plateau (also called the Shillong plateau) and the Karbi Anglong plateau of Assam.

• The Shillong plateau is an outlier of the Peninsular plateau. An outlier is a piece of a larger landform that stands apart from the main body. It is made mostly of very old rocks [4].

• Location: the plateau lies between the Brahmaputra valley (Assam) to the north and the plains of Bangladesh (the Surma–Meghna lowland) to the south.

How it got separated: the Malda fault

• Fault: a crack in the Earth's crust along which blocks of rock have moved up, down or sideways.
• How the plateau was cut off:
• Cause: during the uplift of the Himalayas (Tertiary period), the Indian plate pushed towards the north-east.
• Process: this push opened a huge fault between the Rajmahal hills (Jharkhand) and the Meghalaya plateau. The land between them sank.
• Infill: rivers later filled this low area (a depression) with sediment (sand, silt and clay).

• Result: the Meghalaya and Karbi Anglong plateaus now stand apart from the main Peninsular block. Flat alluvial plains lie in between.

• Malda fault (Malda gap, or Garo–Rajmahal gap): the sunken, sediment-filled zone in West Bengal that separates the north-eastern plateau from the Chotanagpur plateau.

• Effect on drainage:
• The gap sank (was down-thrown) in the mid-Pleistocene.
• After this, the Ganga and the Brahmaputra turned and began to flow towards the Bay of Bengal.

• This explains why the two rivers now meet in Bangladesh and form the Ganga–Brahmaputra delta.

• Why the rocks are the same: both sides of the gap have the same ancient rocks. This is why Meghalaya has the same minerals as Chotanagpur (see the minerals section below).

Feature	Chotanagpur plateau	Meghalaya plateau
Position	Main Peninsular block (Jharkhand and nearby states)	Detached north-eastern piece (Meghalaya)
Separated by	Malda fault / gap (West Bengal), now filled with alluvium	← same gap
Rock age	Ancient (Archaean–Precambrian)	Ancient; an outlier of the Peninsula [4]
Minerals	Coal, iron ore, mica, bauxite etc.	Coal, iron ore, sillimanite, limestone, uranium

The Meghalaya plateau: three hill regions

• The plateau has three parts. From west to east they are the Garo, Khasi and Jaintia hills. Each is named after the tribe living there.

Hills (west → east)	Tribe	Key places
Garo hills	Garo	Tura (town); Nokrek peak
Khasi hills	Khasi	Shillong (state capital); Cherrapunji (Sohra); Mawsynram
Jaintia hills	Jaintia (Pnar)	Eastern end of the plateau; main coal-mining belt

• Eastern boundary: the Kopili river separates the Jaintia hills (Meghalaya) from Dima Hasao district (Assam) [2].
• Kopili river: it rises in the hills of Meghalaya and flows north-west into the Brahmaputra valley in Assam. It is about 290 km long and is the largest south-bank tributary of the Brahmaputra in Assam [2].

Rain and erosion: why the surface is bare

• How the rain forms:
• The moist south-west monsoon winds come up from the Bay of Bengal and blow over the Bangladesh plains.
• They hit the steep southern face of the Khasi–Jaintia hills, which sits like a wall in front of them, and are pushed upward.

• The rising air cools, its water vapour condenses, and very heavy rain falls on the side facing the wind (the windward side).

• Result: Mawsynram and Cherrapunji in the Khasi hills are among the wettest places on Earth. (NCERT: Mawsynram gets the highest average rainfall in the world.)

• Erosion: erosion means rock and soil being worn away and carried off by water or wind.
• Very heavy rain every year washes away the soil, so the plateau surface is highly eroded.
• Cherrapunji has a bare rocky surface with no permanent plant cover. The heavy rain removes the soil that trees would need.
• This is a paradox that exams like to test: one of the wettest places on Earth has bare, rocky ground.

Karbi Anglong plateau

• Karbi Anglong plateau: a detached piece of the Peninsular plateau in central Assam, south of the Brahmaputra. It is the eastward continuation of the Meghalaya plateau.
• It is one of the few landslide-prone parts of Assam, because it is hilly and gets heavy rain. The rest of Assam is mostly flat floodplain.
• The Karbi Anglong hills, together with the Meghalaya hills, separate the Brahmaputra valley from the Barak (Surma) valley.

Minerals

• The rocks are as old as those of Chotanagpur, so the region has similar minerals:
• Coal: the Jaintia, Khasi and Garo hills. Most of it is mined in the Jaintia hills.
• Iron ore
• Sillimanite: a mineral that can stand very high heat. It is used to line furnaces and kilns.
• Limestone: it is quarried and supplies cement plants [4].
• Uranium: a radioactive mineral used as fuel in nuclear reactors. Deposits are found in the Khasi hills.

Life in the hills (Class 7 view)

• Nature: thick, lush forests; heavy rain; many waterfalls, including the Seven Sisters falls near Cherrapunji (Sohra).
• Culture: Shad Suk Mynsiem is a Khasi dance festival of thanksgiving held in spring.
• Mawlynnong (East Khasi hills) is called the "cleanest village in Asia".
• Living root bridges (Jingkieng Jri):
• How they are made: villagers train the roots of the Ficus elastica (rubber fig) tree across a stream. The roots grow into a strong bridge in about 10–15 years [3].
• Spread: about 100 known bridges in 72 villages of the East Khasi hills and West Jaintia hills districts. They connect more than 75 remote villages in and near the wettest region on Earth [3].
• Best-known site: the double-decker bridge near Nongriat.
• Status: placed on UNESCO's World Heritage Tentative List in March 2022 as "Jingkieng jri: Living Root Bridge Cultural Landscapes" [3].
• They grow inside subtropical moist broadleaf forest, and they help villages cope with floods and disasters [3].

Current issue: rat-hole coal mining in the Jaintia hills

• Rat-hole mining: very narrow pits and tunnels, often only big enough for one person to crawl through, dug by hand to reach thin coal seams. It is unsafe and unscientific.
• The problem: rat-hole mining went on in the Jaintia hills for many years without being controlled by any law. Many workers died when flood water entered the mines [2].
• Pollution chain:
• Water flowing out of the coal pits turns acidic. This is called acid mine drainage (AMD).
• The acidic water flows down streams into the Kharkor river, a tributary of the Kopili [2].

• It reaches the Khandong and Umrong reservoirs of the Kopili Hydro Electric Project (Dima Hasao, Assam). The reservoir water became highly acidic and damaged power machines [2].

• Timeline:

Date	Event
17 April 2014	NGT (National Green Tribunal: a special court for environmental cases) ordered that rat-hole and illegal mining stop throughout Meghalaya, and stopped illegal transport of coal [2]
25 March 2015	NGT found fresh mining going on in spite of the ban, and set up the Meghalaya Environment Protection and Restoration Fund [2]
2018	Ksan mine disaster (East Jaintia hills): miners were trapped in a flooded rat-hole mine
31 August 2018	NGT said the ban would continue and set up the Justice B.P. Katakey committee to restore the environment and help victims [2]
3 July 2019	Supreme Court judgment (see below) [2]

• What the Supreme Court said (3 July 2019):
• The MMDR Act, 1957 (Mines and Minerals (Development and Regulation) Act) applies in Meghalaya's hill districts. The Sixth Schedule (special self-rule for tribal areas) does not exempt them, because the President has issued no notification under Para 12A(b) [2].
• In these hills most land is privately or community owned. The owners hold rights over both the surface and the minerals below. They may grant a mining lease, but only with the prior approval of the Central Government given through the State [2].
• Mining with a proper lease and an approved mining plan may go on, and the 2014 NGT ban will not stop it [2].
• Environmental clearance is needed for coal mining of any size of area, under a notification of 15 January 2016 [2].
• Coal that had already been dug out was to be handed over to Coal India Ltd. for sale [2].
• Net effect: rat-hole mining stays banned. Only regulated, scientific mining is allowed.

Prelims Hooks

• Garo → Khasi → Jaintia is the correct west-to-east order of the Meghalaya hills, and all three are named after tribes.
• The Malda fault / gap (West Bengal) separates the north-eastern plateau from the Chotanagpur plateau. Its mid-Pleistocene sinking turned the Ganga and Brahmaputra towards the Bay of Bengal.
• The Meghalaya and Karbi Anglong plateaus are part of the Peninsular block, not the Himalayas. Calling them "Himalayan" is a common trap.
• Place–hill pairs: Tura and Nokrek → Garo hills; Shillong, Cherrapunji (Sohra) and Mawsynram → Khasi hills.
• Cherrapunji gets extremely heavy rain, yet it has a bare rocky surface with no permanent vegetation, because erosion is so strong.
• Meghalaya's minerals include coal, iron ore, sillimanite, limestone and uranium, the same group as Chotanagpur.
• Karbi Anglong is in Assam, not Meghalaya, and it is one of Assam's few landslide-prone areas.
• Kopili is the largest south-bank tributary of the Brahmaputra in Assam, and it separates the Jaintia hills from Dima Hasao [2].
• Living root bridges (Jingkieng Jri) are made from Ficus elastica roots, are found in the East Khasi and West Jaintia hills, and joined the UNESCO Tentative List in 2022 [3].
• The NGT banned rat-hole mining in Meghalaya on 17 April 2014. In 2019 the Supreme Court held that the MMDR Act applies to Sixth Schedule areas [2].

Mains Points

• Plate movement shapes India's land and rivers (GS-I):
• The north-eastward push of the Indian plate opened the Malda gap.
• The gap filled with alluvium and cut the Meghalaya and Karbi Anglong plateaus off from the Peninsula.
• The same event turned the Ganga and Brahmaputra towards the Bay of Bengal.

• This shows how one tectonic event shaped relief, mineral spread and drainage all at once.

• Rain and the shape of the land (GS-I):

• The funnel-shaped southern face of the Khasi–Jaintia hills catches the south-west monsoon and gives record rainfall.
• This causes severe erosion, bare rock surfaces (Cherrapunji) and landslides (Karbi Anglong).

• Living root bridges are a local answer to this climate: low-cost connections that cope with disasters [3].

• Mining versus tribal rights versus environment (GS-III / GS-II):

• Unregulated rat-hole mining in the Jaintia hills caused worker deaths and acid mine drainage, which harmed the Kopili hydro project [2].
• The response came in two steps: the NGT ban (2014), then the Supreme Court's 2019 framework. Mining is allowed only with a lease under the MMDR Act, a mining plan and environmental clearance, while community ownership of land and minerals is respected [2].

• Accidents like the Ksan disaster (2018) show that enforcement is still weak.

• Resources and development (GS-III): coal, limestone (cement) and uranium make this plateau an important store of minerals for the North-east. Using them sustainably needs mining that suits the fragile hills, together with restoration funds such as the MEPRF [2].