At a glance
- Largest of the four divisions by area: the western desert (Thar).
- The Aravalli runs from south-west to north-east and splits the state into two unequal halves: arid to semi-arid in the west, semi-arid to sub-humid in the east.
- The Great Boundary Fault separates the Aravalli rocks from the Vindhyan rocks to their east.
The four divisions
- Western desert (Thar)Dunes and dry plainsPartsDry sandy tract (marusthali); Luni–Jawai basin; Shekhawati region; Ghaggar plainMain featuresWest of the Aravalli; dry and semi-dry; also called the Great Indian DesertShare of area and peopleAbout 61% of the area and about 40% of the people (2011); 130 persons per sq km, the lowest densityFull notes →
- Aravalli hillsAncient fold mountainsPartsSouthern, central and northern AravalliMain featuresDensest and highest in the south; scattered hills in the northFull notes →
- Eastern plainsRiver-built plainsPartsBanas–Banganga basin; Chambal basin; middle Mahi basin (Chhappan plain)Main featuresEast of the Aravalli; built of silt laid by rivers; the Banas–Banganga plain lies at 150–300 m and slopes east; Chhappan is named after a group of 56 villages between Pratapgarh and BanswaraShare of area and peopleAbout 20% of the area and 33% of the people (2011), 332 persons per sq km, the highest density (RBSE); 23.3% of the area (L.R. Bhalla)
- South-eastern plateau (Hadoti)Extension of Malwa plateauPartsKota, Bundi, Jhalawar and Baran districts (RBSE); Bhalla adds parts of Chittorgarh, Bhilwara and BanswaraMain featuresAverage height 500 m; Mukundara and Bundi hills; the Chambal, Kali Sindh, Parwan and Parvati flow hereShare of area and people9.6% of the area (L.R. Bhalla)
Height zones
| Height above sea level | Share of the state | What lies there |
|---|---|---|
| Above 900 m | Less than 1% | High peaks of the Aravalli, including Guru Shikhar |
| 600–900 m | About 6% | The Aravalli ranges; widest from Sirohi, Udaipur and Rajsamand to Ajmer, becoming broken towards Jaipur and Alwar |
| 300–600 m | About 31% | Upland and plateau on both sides of the Aravalli; the north-east part is nearly level (average 400 m), the south-west part is rugged upland (average 500 m); the Hadoti plateau lies in the south-east |
| 150–300 m | About 51% | The western sandy plain and the eastern plain (Banas, Chambal and Chhappan basins) |
Rock formations
| Formation | What it is |
|---|---|
| Banded Gneissic Complex (BGC) | The oldest rocks (Archaean); the basement under the Aravalli and Delhi rocks |
| Aravalli Supergroup | Early Proterozoic metasediments (quartzite, phyllite and others) with some volcanic rocks, resting unconformably on the BGC |
| Delhi Supergroup | The fold belt that forms the backbone of the Aravalli range |
| Malani rocks | Volcanic rocks, chiefly the Malani rhyolites |
| Marwar Supergroup | Stable basin west of the Aravalli, lying over the Malani rocks; the youngest Precambrian rocks beside the range |
| Vindhyan Supergroup | Stable basin east of the Aravalli; conglomerate, shale, sandstone and limestone |
| Deccan Trap | Basalt lava of Cretaceous to Palaeocene age; part of the Hadoti plateau is Deccan lava |
Older books call the Aravalli and Delhi rocks 'systems' (Heron's scheme, with the Raialo series between them); later work calls them supergroups. There is still no accepted succession for all the Delhi basins.
Remember: often mixed up
- Bangar, Bagar, VagadBhalla calls the whole semi-arid belt 'Rajasthan Bangar' (RPSC's Hindi paper: 'Rajasthan Bagad') · RBSE calls the Shekhawati region 'Bagar' · RBSE calls the hilly middle Mahi (Chhappan) plain 'Vagad' (Bhalla: 'Bagad').
Test yourself: asked in exams
CET Senior Secondary Level 2024 · Q53
Which of the following is the biggest geographical region ( area wise) of Rajasthan?
- (1)Semi dry region
- (2)Aravali region
- (3)Western desert plain region
- (4)Eastern plain region
Show answer
✓ (3) Western desert plain region
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