Global Geological And Climatic Events

Palghat Gap: A break in the Western Ghats


From UPSC perspective, the following things are important :

Prelims level: Palghat Gap, Western Ghats

Mains level: Not Much


Central Idea: The article discusses the Palghat (Palakkad) Gap, a significant corridor in the Western Ghats of India. It provides information about the geological origin of the gap.

What is Palghat Gap?

  • The Palghat Gap is a 40 km wide corridor in the Western Ghats, known for its steep hills and serving as a gateway to Kerala.
  • It is a crucial passage for roads and railways connecting Coimbatore and Palakkad.
  • The Bharathappuzha River flows through the Palghat Gap.
  • The vegetation in the gap is classified as dry evergreen forest, different from the tropical rainforests of the Western Ghats.
  • The Palghat Gap marks a distinct divide in the flora and fauna of the region.

Geological origin of the Palghat Gap

  • The Palghat Gap is a geological shear zone running from east to west.
  • Shear zones are weak regions in the Earth’s crust, occasionally causing tremors in the Coimbatore region.
  • The formation of the Palghat Gap occurred when the continental shelves shifted after the separation of Australia and Africa from the Gondwana landmass.
  • India and Madagascar were connected until volcanic activity led to their split, with a similar gap called the Ranotsara Gap in Madagascar.

Biogeographic distinctions and ancient history

  • The biogeographic distinctions in species north and south of the Palghat Gap may be attributed to an ancient river or an incursion of the sea in the distant past.
  • Elephant populations on the Nilgiris side of the gap have different mitochondrial DNA from elephants in the Anamalai and Periyar sanctuaries.
  • DNA analysis of the White-bellied Shortwing, an endemic bird species, shows divergence between populations in the Nilgiris and the Anamalai regions.

Biodiversity south of the Palghat Gap

  • The southern region of the Western Ghats, located south of the Palghat Gap, exhibits high species richness and phylogenetic diversity.
  • A recent study reports over 450 tree species, including ancient species like Magnolia champaca, dating back 130 million years.
  • The warm weather and moist air of the southern Western Ghats support a diverse range of life, making it an island refuge during cycles of ice ages and droughts.
  • The southern Western Ghats receive rainfall more evenly throughout the year compared to the northern region.

Back2Basics: Western Ghats

  • The Western Ghats, also known as the Sahyadri mountain range, is a UNESCO World Heritage Site and one of the 36 biodiversity hotspots in the world.
  • It spans an area of 160,000 sq. km. and stretches for 1,600 km parallel to the western coast of the Indian peninsula, passing through the states of Gujarat, Maharashtra, Goa, Karnataka, Kerala, and Tamil Nadu.
Flora and Fauna The Western Ghats are home to a rich diversity of flora and fauna, including over 7,402 species of flowering plants, 1,814 species of non-flowering plants, 139 mammal species, 508 bird species, 227 reptile species, 179 amphibian species, 290 freshwater fish species, and 6,000 insect species.
Geological Significance The Western Ghats, known as the “Great Escarpment of India,” are older than the Himalayas. They influence India’s monsoon weather patterns by intercepting rain-laden monsoon winds from the southwest during late summer.
Geographic Features Stretching north to south along the western edge of the Deccan Plateau, the Western Ghats separate the plateau from the narrow coastal plain called the Western Coastal Plains, which lies along the Arabian Sea.
Catchment Area The Western Ghats cover a vast catchment area for complex riverine drainage systems, contributing to almost 40% of India’s total drainage. The range acts as a barrier, blocking southwest monsoon winds from reaching the Deccan Plateau.

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