Types of soil:
1. Alluvial soil
2. Black soil
3. Red soil
4. Laterite soil
5. Saline soil
1. Alluvial soil :
Characteristics : Alluvial soils are formed by the deposition of silt by the rivers. It is found in the river valley regions and the coastal plains of Tamil Nadu.
Crops cultivated: Paddy, sugarcane, banana and turmeric.
Distribution: Generally this type of soil is found in the districts of Thanjavur, Tiruvarur, Nagapattinam, Villupuram, Cuddalore, Tirunelveli and Kanyakumari. It is also found to a small extent along the river valleys in few interior districts
2. Black soil:
Formation: Black soil are formed by weathering of igneous rocks.
Characteristics : It is fine textured and clayey in nature. It is poor in phosphoric acid, nitrogen and organic matter.
Creps cultivated: Cotton, Sorghum, Cumbu and fodder crops.
Distributions: It is found in Coimbatore, Madurai, Virudhunagr, Tirunelveli and Thoothukudi districts.
3. Red soil:
Characteristics : This soil is sandy and loamy in texture. Red soil is porous, friable and non-retentative of moisture
Crops cultivated: Paddy, ragi, tobacco and vegetables.
Distribution: It is found in Sivagangai and Ramanathapuram districts.
4. Laterite soil:
Formation: It is formed by the process of intense leaching.
Crops cultivated: Paddy, ginger, pepper, plantains, coffee and tea.
Distribution: Kancheepuram, Tiruvallur, Thanjavur and Nilgiris districts.
5. Saline soil :
It is confined to the Coromandel coast. Vedaranyam has a pocket of saline soil.

Winter season:
a) During January and February, the vertical rays of the sun fall between the Tropic of Capricorn and the Equator. Hence, Tamil Nadu and India on the whole receive slanting rays from the sun.
b) So, the weather is slightly cooler during these months. The difference between summer and winter temperature is not very high. Winter temperature in Tamilnadu varies from 15°C to 25°C
Summer Season:
a) The apparent migration of the Sun towards north during March April and May results in the reception of vertical sun's rays by South India. Thus there is a steady rise in temperature from the equator. Hence, Tamil Nadu located to the south of Tropic of Cancer, experiences high temperature
b) Generally the temperature varies from 30°C to more than 40°C. During this season particularly in the month of May, southern part of the state receives some rainfall from pre-monsoon showers (Mango/Blossom showers) and some parts experience convectional rainfall.

1. The river Cauvery originates at Talakaveri  in the Kodagu district of Karnataka in the Western ghats.
2. It forms Hogenakkal waterfalls in Dharmapuri District.
3. Mettur dam is located across the river in Salem district.
4. A tributary called Bhavani joins Cauvery on the right bank.
5.Two more tributaries Noyyal and Amaravathi confluence Cauvery at Thirumukkudal and this
region is called "Agandra Cauvery".
6. In Tiruchirapalli district, the river branches into two parts. The northern branch is called Coleroon or Kollidam and the southern branch remains the Cauvery. These two again join to form Srirangam Island.
7. Kallanai has been constructed across the Cauvery.
8. The delta of Cauvery in the coast is called as the 'Garden of South India'.
9. It merges into Bay of Bengal to the south of Cuddalore.

i) Plateaus of Tamil Nadu are located between the Western Ghats and the Eastern Ghats.
ii) It is triangular in shape. It covers an area of 60,000 sq.km.
Bharamahal plateau:
i) Bharamahal plateau is a part of Mysore plateau. It is situated in the northwestern part of Tamil Nadu
ii) Dharmapuri and Krishnagiri districts are located in this region.
Coimbatore plateau:
i) It lies between the Nilgiris and Dharmapuri districts.
ii) This region includes Salem, Coimbatore and Erode districts.
iii) Moyar river separates this plateau from the Mysore plateau.
iv) Rivers Bhavani, Noyyal and Amaravathi form valleys in this region.
Sigur plateau:
i) Sigur plateau is an intermontane plateau found in the region of the Nilgiris.
Madurai plateau:
i) Madurai plateau is found in Madurai district.
ii) It extends upto the foothills of the Western Ghats.
iii) Vaigai and Thamirabarani basins are located in this Zone.