Physiographic Divisions of Rajasthan

Rajasthan's terrain is divided into four major physiographic regions that reflect the state's geological history from Pre-Cambrian fold mountains to Pleistocene aeolian deposits.

2.1 Western Sandy Desert / Thar Desert

Area: ~2,09,000 sq km (61.11% of Rajasthan's total area)

The Thar Desert — also called the Great Indian Desert — is the world's 7th largest desert and India's only major hot desert. It lies west of the Aravalli Range in Jaisalmer, Barmer, Bikaner, Jodhpur, Nagaur, Churu, Jhunjhunu, Sikar, and Ganganagar districts.

Landforms within the Thar:

• Sand Dunes: Cover ~40% of the desert area. Classified as:
  • Barchan — crescent-shaped, most mobile, found in Jaisalmer
  • Seif dunes — longitudinal, parallel to wind direction
  • Parabolic dunes — U-shaped
  • Star dunes — multi-armed, stable; highest in the Sam area (Jaisalmer)
• Rocky desert: Stony pediplains with exposed bedrock; Jodhpur-Barmer area
• Sandy plains: Stabilized plains with sparse vegetation cover; Bikaner area
• Playas: Ephemeral salt lakes; examples: Sambhar, Pachpadra, Didwana — discussed under lakes
• Dhands: Seasonal lakes formed by rainwater accumulation; Jaisalmer-Barmer area

Characteristics:

• Annual rainfall: 0–25 cm (less than 10 cm in Jaisalmer)
• Temperature range: −3°C (winter night) to 50°C (summer day)
• Wind velocity: 20–30 km/h on average; dust storms common (May–June)
• Population density: <30 persons/sq km in core desert areas (Census 2011)
• Luni River is the only significant drainage system in this zone

Sam Sand Dunes: The Sam village (45 km from Jaisalmer city) hosts the most accessible barchan dune complex in Rajasthan, now a major ecotourism attraction. The Desert National Park (3,162 sq km, established 1980) covers parts of Jaisalmer and Barmer districts and is the habitat of the critically endangered Great Indian Bustard — cross-reference Topic #85 (Vegetation & Wildlife).

2.2 Aravalli Range

Area: ~31,800 sq km (9.3% of Rajasthan)

The Aravalli Range is among the world's oldest fold mountain systems, formed during the Pre-Cambrian era (2,500 million years ago) through the collision of ancient crustal blocks. The range runs NE–SW from Khetri (Jhunjhunu) in the northeast to Sirohi and Abu in the southwest — a total length of **692 km within Rajasthan** (the full range continues into Gujarat and reaches Delhi, covering ~800 km total).

Key Peaks and Passes:

Feature	Location	Elevation	Significance
Guru Shikhar	Mount Abu, Sirohi	1,722 m	Highest peak in Rajasthan and entire Aravalli
Ser	Sirohi	1,597 m	Second highest peak
Delwara	Sirohi	1,442 m	Third highest peak
Achalgarh	Sirohi	1,380 m	Historical fort site
Taragarh	Ajmer	~870 m	Fort site, central Aravalli
Jarga	Udaipur	1,431 m	Important hill station area
Kumbhalgarh	Rajsamand	~1,087 m	Fort and wildlife sanctuary
Khamnor hills	Rajsamand	~850 m	Source of Banas River

Source: Survey of India; Rajasthan Physical Geography (Rajasthan Board RBSE)

Passes:

• Dewair Pass: Connects Ajmer to Pali
• Pipli Ghat: Connects Ajmer to Nagaur (NH-58)
• Desuri Pass: Pali; historically used by Mughal armies

Geological significance: The Aravalli rocks (Proterozoic to Archean age) host Rajasthan's most valuable metallic mineral deposits — see Topic #88. The Aravalli Supergroup and Delhi Supergroup contain the sulphide ore bodies of the Khetri Copper Belt, Zawar Lead-Zinc mines, and Jhamarkotra phosphate deposit.

Watershed role: The Aravalli acts as the primary drainage divide of the state:

• West of Aravalli: Luni and other rivers drain towards the Arabian Sea or inland
• East of Aravalli: Chambal, Banas, Bandi, Berach drain towards the Bay of Bengal via Yamuna/Ganga

Mount Abu: The only hill station of Rajasthan, at 1,220 m elevation, located in Sirohi district. Surrounded by the Mount Abu Wildlife Sanctuary (288 sq km). Home to the famous Dilwara Jain Temples (11th–13th century) and the Nakki Lake. Average annual rainfall ~150 cm — highest in Rajasthan.

2.3 Eastern Plains / Banas-Mahi Plains

Area: ~78,700 sq km (23.0% of Rajasthan)

The Eastern Plains lie east of the Aravalli Range and are broadly divided into:

1. Banas Plains: Alluvial plains formed by the Banas and its tributaries (Berach, Kothari, Mashi, Khari). Districts: Jaipur, Ajmer, Tonk, Bhilwara, Sawai Madhopur. Fertile agricultural zone — wheat, mustard, bajra cultivation.

2. Mahi Plains: Formed by the Mahi River and tributaries in Dungarpur, Banswara, Pratapgarh. Also called the Vagad region. Tribal-dominated (Bhil communities); known for maize cultivation.

3. Mewar Plains: Central transition zone around Udaipur, Chittorgarh, incorporating both Aravalli foothills and early plains.

Characteristics:

• Average rainfall: 50–90 cm per year (moderate)
• Alluvial and red-yellow soils (see Topic #86)
• More fertile than western and southeastern regions
• Densely populated relative to state average (Census 2011: 165-200 persons/sq km in parts of Jaipur district)

2.4 South-Eastern Plateau / Hadoti Plateau

Area: ~22,600 sq km (6.6% of Rajasthan)

The Hadoti Plateau — named for the Hada Rajput region — is a continuation of the Vindhyan Plateau and Deccan Lava Plateau. It covers Kota, Bundi, Baran, and Jhalawar districts.

Characteristics:

• Elevation: 250–500 m above mean sea level
• Rocks: Vindhyan sandstone and limestone (sedimentary), with parts underlain by Deccan basaltic lava flows (in Jhalawar)
• Famous for the Chambal badlands — deep ravines carved by the Chambal River, especially in Kota-Sawai Madhopur-Dholpur stretch
• Average rainfall: 80–100 cm; highest rainfall in Rajasthan apart from Mount Abu
• Kota stone (limestone flooring tile) comes from this region
• Sehore basin (Baran): Fossil-bearing Cretaceous rocks; dinosaur fossils found at Dhar-Dhar (Baran) in 2022-23 excavations

The Malwa Plateau interface: Jhalawar transitions into the Malwa Plateau of MP; Banas-Parwan rivers drain this area southward. Kota barrage on the Chambal has created a major irrigation network across this plateau.

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