Explanation:

• Usar soil is widespread in India and it is a term collectively applied to all kinds of saline and alkaline soils in the plains of north India, particularly in Uttar Pradesh.
• ‘Reh’ is a white, grayish or ash-coloured salt that are found in low-lying plain areas in dry periods.
• Regolith is simply mineral remains of decomposed rocks (no organic materials). It is soil that contains organic materials – such as roots of plants, fallen leaves, small animals such as worms, bacteria and so on.
• Talus and scree are pile of rocks or collection of broken rock fragments at the base of crags, mountain cliffs, volcanoes or valley shoulders that has accumulated through periodic rockfall from adjacent cliff faces.