Theri Desert

About Theri Desert:

• Most of us may not know the small desert situated in the state of Tamil Nadu. It consists of red sand dunes and is confined to the Thoothukudi district.
• The red dunes are called theri in Tamil.
• They consist of sediments dating back to the Quaternary Period and are made of marine deposits.
• They have very low water and nutrient retention capacity.
• The dunes are susceptible to aerodynamic lift.
• This is the push that lets something move up. It is the force that is the opposite of weight.

Mineral composition of Theris

• The analysis of the red sand dunes reveal the presence of heavy and light minerals.
• These include ilmenite, magnetit, zircon, hematite, quartz etc.
• The iron-rich heavy minerals like ilmenite, magnetite and rutile present in the soil had undergone leaching by surface water.
• They were then oxidised because of the favourable semi-arid climatic conditions.

How did they form?

• Theris appear as gentle, undulating terrain.
• The lithology of the area shows that the area might have been a paleo (ancient) coast in the past.
• The presence of limestone in many places indicates marine transgression.
• The present-day theris might have been formed by the confinement of beach sand locally, after regression of the sea.
• When high velocity winds from the Western Ghats blew east, they induced migration of sand grains and accumulation of dunes.

PRACTICE QUESTION:

Theri Desert is located in which of the following states in India?

(a) Rajasthan

(b) Ladakh

(c) Tamil Nadu

(d) Gujarat

Answer