Question

Thanjavur, Thiruvarur, Nagapattinam, Villupuram, Cuddalore, Tirunelveli, and Kanyakumari districts in Tamil Nadu have ___________.
A) Laterite soils
B) Saline soils
C) Alluvial soils
D) Black soils

Answer 1

Hint:
Soil is a mixture of rock debris and organic materials that develop on the earth’s surface. Vegetation, relief, parent material, climate, and other forms of life and time are the major factors that affect the formation of soil.

Complete Answer:
Other factors that affect the formation of soil like human activities also affect it to a large extent. Components of soil are humus, mineral particles, water, and air.
On the basis of location, color, genesis, and composition, the soils of India are classified into alluvial soils, laterite soils, saline soils, arid soils, forest soils, black soils, red and yellow soils, and peaty soils. Out of these, alluvial soils are widespread in the northern plains and the river valleys. These soils cover about $40\% $ of the total area of the country. They are depositional soils, deposited and transported by streams and rivers. They extend into the plains of Gujarat through a narrow corridor in Rajasthan. They are found in the river valleys and in deltas of the east coast. The nature of these soils varies from sandy loam to clay. They are generally poor in phosphorus but rich in potash. In the Middle and Upper Ganga plain, two different types of alluvial soils have developed, viz. Khadar and Bhangar. The color of the alluvial soils varies from light grey to ash grey. In Tamil Nadu, Thanjavur, Thiruvarur, Nagapattinam, Villupuram, Cuddalore, Tirunelveli, and Kanyakumari districts have alluvial soil.

Thus, option (C) is correct.

Note:
Soil consists of three layers which are called horizons. ‘Horizon A’ is the topmost zone. ‘Horizon B’ is a transitional zone between ‘Horizon A’ and ‘Horizon C’. ‘Horizon C’ is constituted of the loose parent material. In the soil formation process, this layer is the first stage and eventually forms the above two layers. This arrangement of layers is called the soil profile. Underneath these layers is the rock which is also known as the parent rock or the bedrock.