New Delhi, Dec. 28 -- The Supreme Court on Saturday took suo motu cognisance of the contentious issue surrounding the definition of the Aravallis, reopening the possibility of a judicial relook at its recent ruling that restricted the mountain range to landforms rising at least 100 metres above the local relief. The case, titled "IN RE: DEFINITION OF ARAVALLI HILLS AND RANGES AND ANCILLARY ISSUES", will be heard on December 29 by a bench comprising Chief Justice of India Surya Kant and justices JK Maheshwari and AG Masih, in a special sitting. The development assumes significance as the earlier ruling that accepted the contested definition of the Aravallis was also delivered by a three-judge bench led by former Chief Justice of India Bhushan R Gavai. With a bench of equal strength now seized of the issue, the court is empowered to modify or interfere with the previous judgment if it finds merit in the concerns raised, or even refer it to a larger bench in case a more authoritative decision is required. The suo motu proceedings come amid growing public and expert criticism of the definition of the Aravallis that the Supreme Court accepted on November 20, which adopted a committee's recommendation to define the mountain range purely on an elevation-based criterion. Under this definition, only landforms that rise 100 metres or more above the surrounding terrain qualify as Aravallis. The elevation is measured from the base of each hill to its peak, with the "local relief" determined by the lowest contour line encircling the landform. The entire landform within that contour, including the hill, its supporting slopes and associated features, is then treated as part of the Aravallis. Critics have argued that the elevation-based definition marks a sharp departure from the slope-based criteria earlier used by the Forest Survey of India (FSI). In its 2010 mapping exercise, the FSI identified Aravalli landscapes based on slope and geomorphology rather than a rigid height benchmark, a method that environmentalists say offered broader ecological protection. The controversy is not confined to academic debate. Around two weeks after the Supreme Court accepted the elevation-based definition, the Union environment ministry convened a meeting on December 8 to initiate groundwork for delineating which areas of the Aravallis would qualify for a Management Plan for Sustainable Mining (MPSM). Documents from the meeting, reviewed by Hindustan Times and reported on Friday, show that the ministry coordinated a framework under which state governments would work with the Survey of India to map Aravalli areas "as per the definition accepted by the SC on November 20". This delineation exercise, identifying which landforms meet the 100-metre elevation threshold, is intended to form the baseline for all future decisions on mining permissions. Stretching over 700 kilometres from eastern Gujarat to Delhi, through Rajasthan and Haryana, the two-billion-year-old Aravallis are the country's oldest fold-mountain range. The hills play a critical ecological role: they act as a natural barrier preventing the Thar desert from advancing eastwards, serve as a vital groundwater recharge zone, and provide green cover in an otherwise arid landscape....