Free Sample Essay on the Depositional Features of Reivers of Himalaya

The rivers have filled it with silt and other sedimentary deposits. The main depositional features are the following:

(i) Alluvial Fans and Cones.

When the river descends into plain from the hills it forms a conical and convex surfaced feature whose apex lies in the hill where the river enters the plain. The triangular base is at the border of the plain.

It appears like a fan and when its height increases due to the continued deposition it is called cone. With the-exception of Ghagra the whole plain from the west to the cast forms a series of fans and cones.

(ii) Inter-Cones.

This feature is opposed to fans in form. It is concave in nature.

(ii) Piedmont Alluvial Fans.

Where alluvial fans and Inter-cones meet one another, they coalcscc into an alluvial fan plain which is called Piedmont Alluvial Fan. The slope is 1: 10,000. These plains can be seen in northern Bihar as the alluvial fans and intercones made by the Gandak, the kosi and the Mahanadi-Tista Rivers.

The shape of the cones depends upon the alluvial deposition ratio, the volume of water and the shifting routes of the rivers.

(iii) Relief Variations.

Some people think that the plain is almost without any relief. It is not correct. The surface variation is, of course, not as varied as in the Himalayas and in the Peninsula but surface variation is there and it is important.

Most of the surface relief is due to depositional variations. On this basis this plain can be divided into the following four divisions:

(a) Bhabar Terrain

(b) Tcrai Terrain

(c) Bangar Terrain

(d) Khadar Terrain

(a) Bhabar Terrain (Piedmont Plain)

The Bhabar plain continues from the Sindh to the Tista. It is made of coarse material like sand pebbles, gravel, kankar, cobbles etc., which have been brought down from the hills by the streams.

It is in a narrow belt 10-15 km wide. Many streams get lost while crossing the area and reappear in the marshy tracts called Terai.

The great northern plain is almost dead flat-alluvial plain with little relief, which breaks the monotony of the eye. This plain has been created by the deposition of alluvium, brought by the rivers, from the Himalayas.

(b) Terai Terrain

This terrain lies to the South of the Bhabar belt. It is a swampy ill drained and forested area. Agricultural land has been made available by way of cutting vegetation. The region is known for cane cultivation.

Terai is a low lying area criss-crossed by rivulets, nalas. It is an area of wet soils, bog, springs,Tals (small lakes).

It is rich of marshy soils and dense vegetation. However favourable areas have been reclaimed and agriculture is done.

There are a large number of inter-cones, river-levees and alluvial terraces which provide suitable areas for human settlement and developing agriculture.

(c) Bangar Terrain

This area is comparatively a higher part of the plain which remains almost free from the flood water of the rivers. It is made up of old alluvium.

It is mixed with limestone in the form of small cobbles. Bangar is usually an upland area. Barind in the Ganga Delta and Bhur in the Ganga-Jamuna doab are excellent examples of this terrain.

(d) Khadar Terrain

This area is a low lying area. It is in fact the flood plain area.

In khadar, the sediment is fine grained. It is at many places impermeable. Geologically speaking, khadar is of very recent origin.

The rivers bring fine grained sediment with them and deposit it in the flood plain. It is usually deposited in rainy season when the rivers arc in spate. Standing crops arc destroyed. The deltaic silts make Khadar Plains.