Old alluvium and new alluvium in the northern plains of India are called, respectively:

In the Northern Plains of India, the older alluvium is called Bangar, and the newer (younger) alluvium is called Khadar.

Bangar (old alluvium):

• It forms the older, slightly higher parts of the plains, lying above the level of normal floods.
• It is made of older deposits of the Pleistocene period, laid down long ago by rivers.
• It is darker in colour and contains calcareous concretions (nodules of calcium carbonate) called kankar.
• It is less fertile than Khadar, because it is not renewed by fresh deposits.
• It covers most of the upper and middle Ganga plains, including large parts of Punjab, Haryana and Uttar Pradesh.

Khadar (new alluvium):

• It forms the low-lying floodplains along the rivers, which are flooded almost every year.
• Each flood deposits a fresh layer of silt, so the soil is renewed regularly.
• It is lighter in colour, finer and more sandy-loamy in texture, and very fertile.
• It is ideal for intensive agriculture, including rice, wheat, sugarcane, jute and vegetables.
• In Punjab, the Khadar floodplains are called "bet" lands.

Related terms of the Northern Plains:

Bhabar: a narrow belt (about 8 to 16 km wide) of pebbles and boulders along the foot of the Shivaliks. Streams disappear underground here because of the porous material.

Terai: a wet, marshy and densely forested belt south of the Bhabar, where the underground streams re-emerge. Much of it has been cleared for agriculture.

Bhur: elevated patches of sandy soil along the banks of rivers such as the Ganga in the upper doab, formed by wind-blown sand.

Reh or Kallar: saline and alkaline patches in dry areas.

Why not the other options?

• ✗"Khadar and Bangar" reverses the correct order; Khadar is the new alluvium.
• ✗Bhabar and Terai are belts at the foothills of the Shivaliks, not types of alluvium by age.
• ✗Bhur and Kallar refer to sandy patches and saline patches, respectively.