Geography Notes For Competitive Exams: Geological History of India

Geography is a key subject for many competitive exams as it is extremely diverse and dynamic. In this article, we will discuss one of the important topic i.e Geological history of India.Let’s take a look at some of the important geography topics and for the UPSC/ HCS/ PCS Exam.

  Geological History of India 

• The present physical form of the Indian subcontinent is the result of vast geological formation.
• In 1912 a German meteorologist named Alfred Wegener (1880 -1931) hypothesized a single proto-supercontinent named Pangea that divided up into the continents.
• Pangaea, therefore, means "all the Earth." Around the single protocontinent or Pangaea was a single ocean called Panthalassa (all the sea).

Breakup of Pangea

• In contrast to the present Earth and its distribution of continental mass, much of Pangaea was in the Southern hemisphere.
• Pangea started to break up into two smaller supercontinents, called Laurasia and Gondwanaland separated by the Tethys Sea, during the late Triassic era, the first period of the Mesozoic Era which occurred between 251 million and 199 million years ago and also known as the “Age of Reptiles”

Separation of the Indian plate

By the end of Cretaceous period, the continents were separating into land masses that look like our modern-day continents.

• 150 million years ago, the Indian Plate broke from Gondwana land and started its journey towards the North.

• Later, India broke up from Madagascar and started its journey towards Eurasian Plate.

Collision of the Indian plate and Eurasian plate

• India’s northward movement resulted in the collision between the Indian Plate and Eurasian Plate
• After lateral movements between plates, the Himalaya mountain originated.

Geological division of India

India can be geologically divided into 3 parts:

1. Peninsular Plateau
2. Himalayan Ranges
3. Indo- Ganga-Brahmaputra Plain

 Peninsular Plateau 

• The triangular-shaped Peninsular Plateau of India extends from the south of Indo-Ganga Plain to the Cape Comorin (now Kanyakumari). 
• This plateau is one of the oldest surfaces of the Earth and represents a segregated part of the old Gondwanaland.
• It is a highly stable block composed mostly of the Archaean gneisses and schists {Rock System}.

• It has been a stable shield that has gone through few structural changes since its formation.
• Though, Peninsular Plateau is an aggregation of several smaller plateaus, hill ranges interspersed with river basins and valleys but can be broadly divided into two parts:

• Central Highland

• Deccan Plateau

The Himalayan Range

• After the collision of Indian plate with Eurasian plate, Tethys Ocean floor was completely subducted; most of the thick sediments on the Indian margin of the ocean were scraped off.
• These scraped-off sediments are what now form the Himalayan mountain range.
• The Himalayas stretch across the northeastern portion of India. 
• They cover approximately 2,400 km and pass through the nations of India, Pakistan, Afghanistan, China, Bhutan, and Nepal. 
• The Himalayan range is made up of three parallel ranges often referred to as the Greater Himalayas, the Lesser Himalayas, and the Outer Himalayas (Shiwaliks).

The Indo-Ganga-Brahmaputra plains

• After the upliftment of the Himalayas, the northern movement of Indian Plate also created a trough to the south of the Himalayas. 
• The raising of the Himalayas and subsequent formation of glaciers gave rise to many new rivers which supplied more alluvium to intensify the filling of the trough.
• Gradually, the depression got completely filled with alluvium, gravel, rock debris (conglomerates) and the Tethys Sea completely disappeared leaving behind a monotonous aggradational plain. 
• During the recent times (since few million years), depositional work of three major river systems viz., the Indus, the Ganga and the Brahmaputra have become predominant.
• Indo-Ganga-Brahmaputra Plain is the largest alluvial tract of the world.
• It stretches for about 3,200 km from the mouth of the Indus to the mouth of the Ganga. Indian sector of the plain accounts for 2,400 km.
• The northern boundary is well marked by the Shiwaliks and the southern boundary is a wavy irregular line along the northern edge of Peninsular India.
• The western border of Indo-Ganga-Brahmaputra plains is marked by Sulaiman and Kirthar ranges. On the eastern side, the plains are bordered by Purvanchal hills.
• The width of the plain varies from 150 km to 300 km.

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