RPSC RAS/RTS Mains Exam Practice/Mock/Solved/Test Papers in Both Hindi and English.
Western Sandy Plains
(a) Sandy Arid Plains
- Dune free Tract
(b) Semi-Arid Transitional Plains or Rajasthan Bagar
- Luni Basin or Godwar Tract
- Plain of Interior Drainage or Sekhawati Tract
Western Sandy Plain
The western Plain covers a large part of Rajasthan in the west and the northwest of the Aravalli axis. Its northern boundary is marked by Punjab and the southwest by Gujarat and the western boundary is the international boundary between India and Pakistan. The eastern boundary of the western sandy plain is marked by the Aravalli range’s western sub-montane zone up to the northern point of Udaipur district. Beyond which the boundary is marked by the great Indian watershed and 50cm isohyets.
The surface of western Rajasthan is covered with vast stretches of sand occasionally interrupted by rocky protruding right up to the Pakistan border.
The Northwestern division is sandy, poorly watered and sterile. The Rajasthan desert in the west has been subdivided into several natural regions because of the Aravalli hills and the rocky terrain of Barmer-Jaisalmer-Bikaner tract.
Bikaner, Jaisalmer, Barmer, Hanumangarh, Sriganganagar, Jalore, Sirohi, Pali, Jodhpur, Nagaur, Churu, Jhunjhunu and Sikar district are part of western sandy plain and the Luni, Sukri & Jawai rivers flow in rainy season in this area.
Its eastern portion is known as Thar desert which is perfectly dry & with desert Plants and Western Sandy Plain & Pakistan face each other across International boundary for about 1070 Km.
The Western Sandy Plains are subdivided into two units:
(a) Sandy Arid Plain: Minimum rainfall- 50 Cm
There are vast expanses of sand & rock outcrops mainly limestone are found in Jaisalmer, Barmer, Bikaner, Churu, Hanumangarh and Sriganganagar.
It further divided in two small sub groups:
2. Dune Free Tract
1. Marusthali – (Thar Desert)
- It covered Bikaner, Barmer, Jaisalmer, Jodhpur, Nagaur and Churu Area
- Height of sand dunes varies from 6 m to 60 m
- Length of sand dunes – 3 km to 5 km
- Towards west this sandy arid Marushthali is known as Thar Desert.
- The Shifting of sand dunes is locally terms as Dharians.
What are dunes? Explain different type of dunes.
Dunes: In geography, a dune is a hill of loose sand built by Aeolian processes (wind) or the flow of water. Dunes occur in different shapes and sizes, formed by interaction with the flow of air or water.
1. Longitudinal Dunes
- These are mostly run from south west to north east
- Parallel to the prevailing winds & mostly sword-shaped type.
- Its Longer axis is parallel to the direction of wind
2. Transverse Dunes
- These types of dunes are formed across the wind direction.
- Commonly found in eastern & northern parts of Marusthali.
- Windward side is long & gently sloping, while leeward side is steep and abrupt.
- These are also called U-shaped dunes.
3. Crescent Shaped Dunes
- The Width of these types of dunes varies from 100 m to 200 m height of dunes-10 m to 20 m.
- The dunes have a gently sloping convex windward side & steep leeward
- These are found in isolation or occasionally side by side in lines.
2. Dune Free Tract
- It is rocky but dune free tract.
- Bikaner, Jaisalmer, Phalodi & Pokhran are known as dune free areas.
- Limestone & Sandstone rocks exposes here belong to Jurassic & Eocene formations.
- Gneiss, Grid conglomerate, schist & granite rocks are also exposed at places.
(b) Semi-Arid Transitional Plain or Rajasthan Bagar
The line dividing the Sandy Arid Plains and the Semi-Arid Transitional Plain is climatic, i.e. 25cm isohyets. The western-most belt which is ‘The Great Desert’ is covered by sand dunes which stretch from the Great Rann along the Pakistan border to Punjab. The degree and extent of sand dunes greatly influence the economic activity in this area. 63 per cent sand dune area of Rajasthan is concentrated in the desert districts of Barmer, Jaisalmer and Bikaner.
- Jaipur, Jodhpur, Nagaur, Pali, Jalore, Barmer districts covered in semi arid.
- Area – 7500 Sq. Km
- Rainfall – 20 cm
- Gullying has given rise to conglomerate landscape. Its eastern part is covered with superficial sand deposits.
Towards north lies the Shekhawati tract which is semi arid transitional plain characterized by inland drainage & stream with salt lakes. Ghaggar Plain lies in extreme north.
Semi-Arid Transitional Plain or Rajasthan Bagar divided into:
1. Luni Basin: This area is locally known as Naid and is one of best alluvial plains and flood occurs during the rainy season in Luni River.
The Luni River originates from western slopes of Naga hills of Aravalli Range near Ana sagar lake, Ajmer. Barmer, Jalore, Jodhpur and Nagaur districts are part of this basin and the total Area is 34866 .4 Sq. Km.
Basin is drained by the Luni river & its tributaries Bandi, Saagi, etc. Covers the area from its source to Tilwara in Barmer where Sukari river meets it.
2. Shekhawati Region: Aravalli hills runs through this region from south to north, cutting into almost two halves and Churu, Sikar, Jhunjhunu & Nagaur districts are part of this region; the main occupation of this region is live stock, Milk production & dairy.
Topography of the Shekhawati tracts is characterized by an undulating sandy terrain traversed by longitudinal sand dunes. Kantli is the only seasonal river.
3. Ghaggar Plain: Hanumangarh & Sriganganagar districts are part of this plain. There is no stream or river except Ghaggar Nali which flows through the ancient bed of Ghaggar river which is now extinct; this region is known as Ghaggar Plain. This plain is a sandy plain interspersed with sand-dunes &small sand-hills. A large part of it is dreary & full of sand dunes. Northern part of this region is fully canalled & thus is made productive. Sand ridge dunes are found on the bank of ancient rivers height of sand ridge dunes-6 m to 30 m.
4. Nagauri Upland: Average height of this region from sea level is 300 m to 500 meter and the rainfall in this region is 25 cm in west to 50 cm in east. This region is full of sand hills & low depressions and the temperature being high, the evaporation of the saline flood water results in the deposits of the Salt & Soda in the depression.