India’s oldest mountain system has unexpectedly become the focus of a major legal and ecological debate. Stretching nearly 680 km from Gujarat to Delhi and more than two billion years old, the Aravalli ranges are central to north-west India’s environmental stability. Yet, a seemingly technical issue—how the Aravallis should be legally defined—now carries far-reaching consequences for mining, conservation and governance.
Why the Aravallis are ecologically indispensable
The Aravalli ranges act as a natural barrier against the eastward spread of the Thar Desert. They deflect westerly winds and help bring winter rainfall to Punjab, Haryana, Delhi and western Uttar Pradesh. Beyond climate regulation, the hills support groundwater recharge, sustain biodiversity in semi-arid landscapes, and stabilise fragile ecosystems.
Tree cover across the Aravallis also functions as an important carbon sink, contributing to the mitigation of winter air pollution in the Delhi NCR region. In ecological terms, the ranges perform functions disproportionate to their modest height.
The Supreme Court’s intervention on defining the Aravallis
On 5 May 2024, the Supreme Court of India directed the Union government to evolve a uniform definition of the Aravalli ranges. In response, the Ministry of Environment, Forest and Climate Change (MoEFCC) constituted a high-level panel led by its Secretary, with members from the Forest Survey of India, Geological Survey of India and the Central Empowered Committee.
The panel examined minimum, maximum and average elevations across 34 districts spread over Gujarat, Rajasthan, Haryana and Delhi. The exercise revealed a core difficulty: while the Aravallis are geologically continuous, their surface topography is highly uneven.
Why elevation and slope are inadequate markers
The panel found wide variations in average elevation across districts. Some districts have hilly terrain that does not belong to the Aravalli system, while large parts of the geological Aravalli range are not distinctly hilly at all. As a result, neither elevation nor slope can cleanly separate Aravalli landforms from surrounding terrain.
If slope is used as the primary criterion, non-Aravalli areas risk inclusion. If elevation alone is adopted, significant parts of the true Aravalli system may be excluded. This exposes the limits of using simple physical parameters to define a complex geological formation.
How states historically identified the Aravallis
Amid rising ecological pressure from mining, the Supreme Court in August 2025 asked states to justify their definitions. Rajasthan reported that it relies on Richard Murphy’s 1968 land reforms classification, which defines hills as areas above 100 metres elevation, including supporting slopes down to the lowest local contour.
Gujarat and Haryana follow the same approach, while Delhi clarified that mining is prohibited in its ridge areas, regardless of elevation.
Resource wealth and the conservation dilemma
While underscoring the ecological importance of the Aravallis, the MoEFCC panel also highlighted the region’s mineral richness. The ranges contain base metals such as lead, zinc and copper, precious metals like gold and tungsten, and—particularly in Delhi—critical and rare earth minerals such as lithium, nickel and niobium. These resources are vital for energy transition technologies, advanced manufacturing and national security.
This dual reality has complicated policy choices between conservation and extraction.
The 100-metre definition and competing assessments
The panel recommended defining the Aravallis as landforms in Aravalli districts with elevations of 100 metres or more from local relief, along with supporting slopes and associated landforms. The Supreme Court approved this definition on 20 November 2025.
However, this clashed with earlier Forest Survey of India assessments based on a 3-degree slope criterion. Under the slope method, 15 districts in Rajasthan alone had over 40,000 sq km classified as Aravalli hills, with more than 12,000 hills mapped. Only about 1,000 of these exceeded 100 metres in elevation. The new definition would exclude nearly 90 per cent of hills previously identified.
Conversely, MoEFCC informed the Court that 12 of the 34 Aravalli districts would fall outside the definition if slope alone were used. Each approach, therefore, invalidates large areas recognised by the other.
Judicial pause and unresolved implications
Acknowledging the stakes, the Supreme Court took suo motu cognisance and on 29 December 2025 stayed its approval of the 100-metre definition. It ordered the constitution of an expert committee to examine environmental impacts before arriving at a final position.
A larger concern also surfaced: India has no legal definitions of hill systems based on elevation or slope for ranges such as the Himalayas, Western Ghats, Vindhyas or Satpuras. Applying such criteria to the Aravallis could open lower hill systems across the country to intensive mining.
Mining pressure versus restoration commitments
Rajasthan alone has over 1,200 mining leases covering more than 17,000 hectares within the Aravalli region, many of which are under dispute. Although the state notified new leases, a recent central ban has put them on hold.
At the same time, MoEFCC announced an ambitious 1,400-km green wall project across Gujarat, Rajasthan, Haryana and Delhi, aimed at reforesting 1.15 million hectares along foothills and buffer zones by 2027 using native species. However, there is limited public information on progress made so far, raising questions about implementation.
What to note for Prelims?
- Geographical spread and ecological role of the Aravalli ranges
- Institutions involved in defining the Aravallis
- Difference between elevation-based and slope-based definitions
- Green wall initiative along the Aravallis
What to note for Mains?
- Difficulties in legally defining ecological landscapes
- Conservation–mining trade-offs in mineral-rich regions
- Role of the judiciary in environmental governance
- Policy contradictions between ecological restoration and regulatory frameworks
