ARAVALLI RANGE
1. Context
The Supreme Court (SC), in an order last month, settled on a uniform definition of the Aravalli hills and ranges, and paused the grant of fresh mining leases inside its areas spanning Delhi, Haryana, Rajasthan and Gujarat.
2. Significance of the Aravalli range
- Beyond being almost two billion years old and the oldest mountain system in India, these hills function as a vital ecological shield against the advance of desert conditions into the Indo-Gangetic plains.
- They act as a natural barrier slowing the eastward expansion of the Thar Desert into Haryana, Rajasthan, and western Uttar Pradesh. The range plays a crucial role in climate regulation, biodiversity conservation, and groundwater replenishment.
- Extending roughly 650 km from Delhi to Gujarat, it supports key water-recharge networks and gives rise to major rivers such as the Chambal, Sabarmati, and Luni.
- The region is abundant in building stones like sandstone, limestone, marble, and granite, as well as minerals including lead, zinc, copper, gold, and tungsten.
- Although these resources have been extracted for centuries, the last forty years have seen rampant stone and sand quarrying, leading to declining air quality and a sharp reduction in groundwater recharge.
- Part of this mining activity has occurred unlawfully. The Court also observed that India has international obligations under the United Nations Convention to Combat Desertification to safeguard fragile ecosystems like the Aravalli range
3. Geological & Physical Features of Aravalli
- The Aravalli Range is one of the oldest fold mountain systems in the world, with its geological origins dating back nearly two billion years to the Precambrian era.
- Unlike young fold mountains such as the Himalayas, the Aravallis have undergone extensive weathering and erosion over millions of years, which has reduced them to a series of low-lying hills, ridges, and rocky outcrops rather than sharp peaks.
- This long geological history makes the range a valuable record of early crustal evolution and ancient tectonic processes on the Indian subcontinent.
- Geologically, the Aravallis are composed primarily of metamorphic and igneous rocks, including quartzite, schist, gneiss, marble, and granite. These rock formations are part of the Aravalli–Delhi orogenic belt, which was formed due to ancient tectonic collisions and crustal movements.
- The presence of economically significant minerals such as copper, lead, zinc, gold, and tungsten reflects the complex geological processes that shaped the region. Over time, repeated uplift and denudation exposed these mineral-rich formations at the surface, making the range an important mining zone historically.
- Physically, the Aravalli Range stretches for about 650 kilometres in a south-west to north-east direction, beginning near Palanpur in Gujarat and extending through Rajasthan to Haryana and Delhi.
- The range is discontinuous in nature, with broken hill chains and isolated ridges rather than a continuous mountain wall. Its highest peak is Guru Shikhar in the Mount Abu region of Rajasthan, rising to about 1,722 metres above sea level.
- Moving northwards, the height of the range gradually declines, merging into low hills and rocky terrain around Delhi.
- The Aravallis play a significant role in shaping the physical geography of north-western India. Acting as a natural climatic divide, they influence rainfall patterns by intercepting south-west monsoon winds to a limited extent and preventing the unchecked eastward expansion of the Thar Desert.
- The range also forms an important watershed, giving rise to several seasonal and perennial rivers such as the Chambal, Sabarmati, Luni, and Banas.
- The fractured and porous nature of its rock formations allows rainwater to percolate underground, contributing substantially to groundwater recharge in an otherwise semi-arid region
4. What is the “100-metre definition” of Aravalli Hills?
- The “100-metre definition” of the Aravalli Hills refers to an administrative and legal criterion used—especially in environmental regulation and court proceedings—to identify and protect the Aravalli region.
- Under this definition, any area that rises more than 100 metres above the surrounding plain is treated as part of the Aravalli hill system, irrespective of whether it is a prominent mountain, ridge, or a low, eroded hill. In other words, even subtle elevations and fragmented hillocks that meet this height threshold are classified as Aravalli features.
- This definition became important because the Aravallis are very old and heavily eroded, meaning many sections no longer appear as classic mountains. If protection were limited only to visibly high or continuous hills, large portions of the range—especially in Haryana, Rajasthan, and the Delhi-NCR region—would fall outside legal safeguards.
- The Supreme Court and various environmental authorities have relied on the 100-metre criterion to prevent mining, construction, and land-use change in ecologically sensitive areas of the Aravalli range.
- By using a measurable elevation benchmark rather than appearance alone, the definition helps expand environmental protection to degraded and fragmented parts of the hills
5. Supreme Court Intervention and Uniform Definition
- The Supreme Court’s intervention in the Aravalli region arose from growing concerns over rampant mining, construction, and land-use changes that were degrading this fragile and ancient mountain system.
- One of the core problems identified by the Court was the absence of a uniform and scientifically grounded definition of the Aravalli Hills.
- Different States and authorities were using varying criteria—based on revenue records, forest classification, or visual identification—allowing large tracts of the Aravallis to be excluded from protection and opened up for exploitation.
- To address this ambiguity, the Supreme Court emphasised the need for a uniform definition applicable across States, particularly Rajasthan, Haryana, and Delhi, where the Aravallis are most fragmented and vulnerable.
- The Court endorsed an objective, elevation-based approach, popularly referred to as the “100-metre definition”, under which land rising more than 100 metres above the surrounding plains would be treated as part of the Aravalli hill system.
- This was intended to ensure that even low, eroded, or discontinuous hill formations, which are characteristic of the Aravallis due to their great geological age, are brought within the protective framework.
- Through its interventions, the Supreme Court also linked the protection of the Aravallis to India’s international environmental obligations, particularly under the UN Convention to Combat Desertification (UNCCD).
- The Court observed that the degradation of the Aravalli range could accelerate desertification in north-western India and undermine groundwater recharge, air quality, and regional climate stability.
- Consequently, it directed governments to adopt a consistent and precautionary approach in identifying, mapping, and regulating activities in the Aravalli region
6. Action against mining
- Since the early 1990s, the Union Environment Ministry has framed regulations permitting mining only in projects that receive official approval, but these safeguards have been widely disregarded.
- In response to persistent violations, the Supreme Court intervened in 2009 and enforced a complete ban on mining activities in Haryana’s Faridabad, Gurugram, and Mewat districts.
- More recently, in May 2024, the Court halted the issuance and renewal of mining leases across the Aravalli range and instructed its Central Empowered Committee (CEC) to carry out an in-depth review. This exercise culminated in a set of recommendations submitted in March 2024.
- The CEC advocated a holistic strategy that called for scientifically mapping the entire Aravalli system across States, conducting a broad-scale environmental impact assessment of mining operations, and enforcing an absolute ban on mining in ecologically fragile zones.
- These included wildlife-protected areas, water bodies, tiger corridors, critical groundwater recharge regions, and locations within the National Capital Region.
- The Committee also stressed the need for tighter controls over stone-crushing units and advised that no fresh mining permissions or lease extensions be granted until comprehensive mapping and impact studies were completed.
- The Supreme Court incorporated these recommendations in its order issued in November 2025.
- In addition, in June 2025, the Union government launched the Aravalli ‘Green Wall’ initiative, aimed at increasing vegetation cover in a five-kilometre buffer zone around the range across 29 districts in Gujarat, Rajasthan, Haryana, and Delhi.
- According to the government, this programme is expected to make a significant contribution towards the restoration of 26 million hectares of degraded land by the year 2030.
7. Way Forward
The Court observed that earlier instances demonstrate how absolute prohibitions frequently give rise to illegal mining networks, aggressive sand mafias, and uncontrolled resource extraction. Consequently, instead of enforcing a complete shutdown, the Court adopted a balanced strategy—allowing lawful mining operations to proceed under strict oversight, placing a temporary halt on new mining activities until a science-based framework is developed, and keeping ecologically critical zones permanently closed to mining
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For Prelims: Aravalli ranges, UN Convention to Combat Desertification (UNCCD)
For Mains: GS I - Indian Geography
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Source: The Hindu
