Red Dunes

In News

• There is a small desert situated in the state of Tamil Nadu. It consists of red sand dunes and is confined to Thoothukudi district.

About Red Dunes

• Location: The dunes are spread over Kuthiraimozhi theri and Sathankulam reserve forest of Tiruchendur taluk, which is located on the shoreline overlooking the Bay of Bengal in the south-eastern part of Tamil Nadu.
• Theri: The red dunes are called theri in Tamil.
• Quaternary Period: They consist of sediments dating back to the Quaternary Period and are made of marine deposits.
• Low capacity: They have very low water and nutrient retention capacity.
• Aerodynamic lift: 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.
• Presence of heavy and light minerals: The petrographical study (petrography is the study of composition and properties of rocks) and X-ray diffraction analysis (a method used to determine a material’s crystallographic structure) of the red sand dunes reveal the presence of heavy and light minerals.
  • These include Ilmenite, Magnetite, Rutile, Garnet, Zircon, Diopside, Tourmaline, Hematite, Goethite, Kyanite, Quartz, Feldspar, Biotite.

Various theories of formation

• Marine transgression: The lithology (the study of general physical characteristics of rocks) 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.
• High velocity winds: 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.
• South west monsoon winds: The red sand is brought from the surface of a broad belt of red loam in the plains of the Nanguneri region by south west monsoon winds.
  • When the dry monsoon wind blows with high velocity, the red loam is churned and driven east in huge columns of red sand, till they are met by sea breeze near the coastal tract of Tiruchendur and get deposited there.
• Aeolian processes: processes of erosion, transport and deposit of sediments that are caused by wind at or near the surface of the earth, are called Aeolian processes.
  • They lead to continual sand redistribution.

Source: DTE