The Aravalli Hills and Ranges constitute one of the most ancient geological formations in the world dating back to the Proterozoic eon’s Paleoproterozoic era. They extend as a continuous geological ridge from Gujarat through Rajasthan and Haryana up to Delhi, covering about 37 districts across four states and the National Capital Region (NCR). Over centuries, the Aravallis have functioned as an ecological shield for northern and north-western India, moderating climate, arresting desertification, recharging groundwater, and sustaining biodiversity and livelihoods.
In recent decades, however, the Aravallis have become the subject of intense legal and policy scrutiny due to mining, urbanisation, forest loss, and definitional ambiguities. The Supreme Court (SC) has recognised the Aravallis as an ecological barrier of national importance and noted that lack of a uniform definition across various states, including Haryana, has enabled regulatory ambiguity, which, in turn, facilitated rampant illegal mining. Recent judicial developments culminating in the SC’s orders of November–December 2025, including the constitution of an expert committee led by the Ministry of Environment, Forest and Climate Change (MoEFCC) and the subsequent stay of judgment, have brought into sharp focus the question of whether and how the Aravallis matter, particularly with respect to their topographical, geological, ecological, and legal significance.
Geological Antiquity and Topographical Character
The Aravalli range is over a billion years old, formed through tectonic processes that shaped the Earth’s crust. It is among the oldest fold mountain systems in the Indian subcontinent, predating even the Himalayas. Extensive erosion over deep geological time has resulted in low-relief hills, discontinuous ridges, slopes, valleys, and hillocks rather than sharp and continuous mountain peaks.
Topographically, the Aravallis stretch for nearly 700 km, with around 560 km lying in Rajasthan. As they enter Delhi, they thin into the Delhi Ridge, often described as the ‘green lungs’ of the city and as a ‘morphological ridge’ that performs critical ecological functions even where formal notification is absent.
The present-day Aravallis are characterised by highly weathered, fractured, and porous rock formations. These geological features are central to their ecological role. Vertical fractures and weathered zones allow rainwater to percolate deep underground rather than running off the surface, creating extensive but invisible groundwater reserves. The range also acts as a natural barrier between the Thar Desert and the Indo-Gangetic plains, slowing dust-laden winds and moderating temperature extremes. Although erosion and human activity have created several gaps in the range, even in this fragmented state, the Aravallis continue to perform landscape-level ecological functions.
Ecological Functions and Environmental Significance
Ecologically, the Aravallis are widely recognised as a barrier against desertification, particularly preventing eastward movement of desert sands from the Thar Desert into the fertile plains of north India. The range contributes to air-quality regulation in the Delhi-NCR region by filtering dust and reducing wind velocity. The loss of vegetated hills has already been linked to an increasing frequency of dust storms, deterioration in air-quality index levels, and rising night-time temperatures associated with the urban heat-island effect.
The hills are also a major groundwater-recharge zone. Rainwater entering the fractured rocks-system moves into aquifers, where it is protected from evaporation. Recharge functions extend beyond hilltops to include slopes, foothills, valleys, and inter-hill corridors, explaining why groundwater in the Aravalli region is often of relatively low salinity. These recharge processes play a vital role in sustaining water availability across Delhi, Gurugram, Faridabad, Haryana, Rajasthan, and several parts of western India.
The Aravallis function as one of the principal watersheds of the subcontinent, separating drainage flowing towards the Bay of Bengal through rivers, such as the Chambal and Yamuna tributaries from drainage flowing towards the Arabian Sea through rivers, such as the Mahi, Sabarmati, and Luni. Important lakes and wetlands, including Sambhar, Sultanpur, Pushkar, Fateh Sagar, and Jaisamand are integrally linked to this system.
In terms of biodiversity, the Aravalli landscape supports dry deciduous and semi-arid ecosystems, including scrub forests and savanna-type forests. The range contains 22 wildlife sanctuaries, 16 in Rajasthan, including tiger reserves such as Ranthambore, Sariska, and Mukundra while the remaining six spread across Haryana, Gujarat, and Delhi (NCT). It supports species such as tiger, leopard, sloth bear, sambar, chital, hyena, wolf, jackal, blackbuck, gharial, and crocodile. Smaller hillocks, slopes, and intervening corridors serve as wildlife movement pathways and ecological connectors. Fragmentation caused by mining and construction has disrupted these corridors, leading to increased human-wildlife conflict.
Beyond ecological services, the Aravallis sustain local livelihoods. Communities depend on fuelwood, fodder, fruits, vegetables, medicinal plants, and grazing lands. Pastoral communities and small farmers have been directly affected by falling water tables, the loss of commons, and the hazards created by abandoned mining pits.
Mining Pressure, Degradation, and Historical Context
The Aravallis are also a repository of metals and minerals, including lead, zinc, copper, gold, and tungsten besides critical minerals such as tin, graphite, molybdenum, niobium, nickel, lithium, and rare-earth elements. This mineral wealth has made the region vulnerable to extensive legal and illegal mining. Satellite imagery over recent decades shows severe fragmentation, particularly in Haryana and Rajasthan, where once-continuous ridges have been reduced to isolated patches.
Judicial intervention in the Aravallis dates back to the mid-1990s through landmark public-interest litigations, such as T.N. Godavarman Thirumulpad vs Union of India and M.C. Mehta vs Union of India. In 1996, mining and construction were prohibited in parts of the Faridabad Aravallis after official reports highlighted ecological degradation. In 2002 and subsequent years, the SC restricted mining in Haryana based on the findings of widespread illegal quarrying by the Central Empowered Committee (CEC). Orders throughout the 2000s mandated environmental clearances, monitoring mechanisms and removal of encroachments, forming the backbone of enforcement against illegal mining.
In 2010, when Rajasthan relied on a 100-metre height rule to identify the Aravalli hills, the SC rejected this approach and directed the Forest Survey of India (FSI) to conduct a scientific survey of the entire hill range, emphasising that the exercise should not be confined to peaks above 100 metres. The FSI, working with the CEC, mapped over 40,000 square kilometres as Aravalli terrain using slope-based criteria. Despite these directions, illegal mining continued. In 2018, the CEC reported that 31 out of 128 sampled hill features in Rajasthan had ‘vanished’ due to illegal mining, prompting sharp judicial criticism of state inaction. Large breaches created across the range weakened its dust-barrier function and aggravated air pollution in Delhi-NCR.
The court also addressed unauthorised real-estate developments, notably ordering demolition of structures in Kant Enclave, Faridabad, emphasising that damage to the Aravallis is irreversible. In Delhi, the concept of the morphological ridge was developed with extended protection, even in the absence of formal notification, followed by statutory status for the Delhi Ridge Management Board under the Environment (Protection) Act, 1986.
The 2024–25 Committee Process and Operational Definitions
In January 2024, while considering mining-lease renewals in Rajasthan, the SC revisited the adequacy of existing definitions used to regulate mining. An expert committee was constituted comprising representatives of the MoEFCC, forest departments of Delhi, Haryana, Rajasthan, Gujarat, the FSI, the Geological Survey of India, and the CEC. Technical sub-committees were also formed to provide the scientific inputs. Consultations revealed that Rajasthan was the only state with a long-standing operational definition for regulating mining, based on the Richard Murphy landform classification adopted in 2006. Other states either relied on ad hoc criteria or lacked any formal definition. All states agreed to adopt the Rajasthan criterion as a baseline while strengthening it to make it objective, transparent, and conservation-centric.
The committee recommended a uniform operational definition for mining regulation. Aravalli Hills were defined as any landform in the Aravalli districts having an elevation of 100 metres or more above the local relief, determined by the lowest contour line encircling the landform. The entire landform within this contour, including supporting slopes and associated landforms irrespective of gradient, was to be treated as part of the Aravalli Hills. Aravalli Ranges were defined as two or more such hills within 500 metres of each other, with all landforms between them included as part of the range. The committee clarified that the definition was intended solely for regulating mining and not for redefining the geological or ecological identity of the Aravallis. It cautioned against interpreting the threshold as permission to mine all lower-elevation landforms and recommended mandatory mapping on Survey of India toposheets, identification of core or inviolate areas, sustainable mining guidance and strict measures to prevent illegal mining.
In its judgment dated November 20, 2025, the SC accepted these recommendations, commended the committee’s work, and imposed an interim moratorium on new mining leases until a Management Plan for Sustainable Mining (MPSM) is prepared by the Indian Council of Forestry Research and Education (ICFRE). Mining was prohibited in core or inviolate areas except for narrowly defined critical, strategic and atomic minerals under the Mines and Minerals (Development and Regulation) Act, 1957.
Legal Dimensions, Safeguards, and Regulatory Framework
The accepted framework integrates environmental regulation with legal enforceability. Mining is absolutely prohibited in protected areas, tiger reserves, eco-sensitive zones, wetlands, and areas with plantations raised through Compensatory Afforestation Fund Management and Planning Authority (CAMPA) or public funds. Where eco-sensitive zones are pending or smaller in extent, a one-kilometre buffer from protected area boundaries apply. Wetlands notified under the Wetlands (Conservation and Management) Rules, 2017 are also excluded.
Existing and renewal leases are subject to inspection by expert teams and continuous monitoring by pollution control boards. Environmental clearance, forest clearance, compensatory afforestation, wildlife management plans, groundwater safeguards, and cultural-heritage clearances are mandatory.
The court also emphasised surveillance-based enforcement using drones, CCTV, weighbridges, district-level task forces, and strict logistics oversight. The forthcoming MPSM is required to identify permissible and prohibited zones, assess cumulative environmental impacts and ecological carrying capacity, and mandate post-mining restoration and rehabilitation.
Critique, Controversy, and the December 2025 Stay
Despite safeguards, the November 2025 judgment triggered widespread concern and protest. Critics argued that the elevation-based definition created a problem of negative definition by clearly delineating what is protected while implicitly exposing what falls outside protection. The FSI mapping indicated that out of more than 12,000 potential geological formations, only about 1,048 satisfied the 100-metre threshold, raising fears that a large proportion of the range could be exposed to mining and development. Historical experience in Rajasthan, where the same criterion had been applied since 2006, reinforced these concerns.
Environmental commentators highlighted that the Aravallis function as an interconnected hydrological and ecological system whose groundwater recharge, biodiversity connectivity and desertification-control functions do not align neatly with elevation measurements. Concerns were also raised about the exclusion of gaps and corridors between hills, which could weaken ecological connectivity if opened to regulated mining.
On December 29, 2025, a CJI-led bench of the SC stayed the November 2025 judgment, acknowledging that further clarification was required and that the earlier directions may have created a structural paradox between legal taxonomy and ecological protection. The stay reflects judicial recognition that translating ecological realities into justiciable legal standards is a fundamental challenge in environmental governance, where the need for bright-line rules must be balanced against the precautionary principle articulated in cases, such as Vellore Citizens Welfare Forum vs Union of India.
Conclusion
The Aravallis matter not only as an ancient geological formation but as a living ecological system whose topography and geology underpin climate regulation, water security, biodiversity, and human well-being across a vast region. The legal history of the Aravallis demonstrates sustained judicial engagement to protect this landscape, even as definitional ambiguities and enforcement failures have allowed degradation to continue. The recent committee process and SC orders represent an attempt to reconcile administrative clarity with ecological protection, yet the ensuing controversy and stay underline the complexity of the task. As debates over definitions, mining, critical minerals, and sustainable development continue, the Aravallis stand as a reminder that ecological systems could not be reduced solely to numerical thresholds without risking the very functions that make them vital to the nation.
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