How India formed from five ancient cratons

The Indian subcontinent first formed about three billion years ago, when five ancient blocks of crust called cratons joined together. The seams where they met still shape India's mountains, rifts and valleys today.

About three billion years ago, the Indian subcontinent first came together as an assembly of five ancient, stable pieces of Earth’s crust called cratons. These were the Dharwar Craton in the south, Bastar Craton in central India, Singhbhum Craton in the east, Bundelkhand Craton in the north, and the Aravalli–Marwar Craton in the northwest. Together they formed the core of the subcontinent, known as the Indian Shield.

Cratons are ancient and extremely stable, but the seams where they joined, called sutures, are relatively weaker. Because of this, most of the tectonic activity is concentrated along these boundaries. Think about a train where all the coaches are joined together. Whenever the engine brakes, the pressure is felt between the coaches as compression, and when it accelerates, the force is felt as extension. In the same way, over millions of years these cratons felt compression or extension along their boundaries. This created ranges like the Aravalli and Satpura, and valleys and rifts like the Godavari and Narmada. You can still see the clues of these ancient sutures on a map of India today.

The five cratons do not cover the entire area of modern India, because the shield kept growing over time. For example, the massive volcanic eruptions that formed the Deccan Traps added a huge volume of rock to central and southern India. When the Indian Plate eventually collided with the Eurasian Plate, it gave rise to the Himalayas, and the immense weight of these mountains caused the Indo-Gangetic Plain to form in front of them as a basin that slowly filled with sediments. In the east, tectonic forces created the Indo-Burma mountain belt. Over roughly the last 50 million years, these additions gave the Indian subcontinent its present-day shape.

The cratons of northeast India are still being studied. Several recent studies suggest that the Assam–Meghalaya Plateau may be an extension of the Bundelkhand Craton that later drifted and was uplifted, as India broke away from Gondwana and eventually collided with Eurasia.

Key terms

Craton

An ancient, exceptionally stable block of continental crust, and some of the oldest and most rigid rock on Earth.

Indian Shield

The core of the subcontinent, formed when the five cratons welded together during the Archean.

Suture (mobile belt)

The weaker boundary zone where two cratons joined. Because it is weaker than the cratons, this is where mountains, rifts, and valleys tend to form.

Lithosphere

The rigid outer shell of the Earth, made of the crust plus the topmost solid mantle, that forms and moves as tectonic plates.

Deccan Traps

One of the largest volcanic events in Earth's history, which flooded much of central and southern India with lava and added new rock to the shield.

Sources & further reading

Start here — free & accessible

“Major Tectonic Features of Peninsular India” — eGyanKosh (IGNOU) A good free resource.

The textbook

K. S. Valdiya — “The Making of India: Geodynamic Evolution” Comprehensive geology of the subcontinent (a bit expensive to buy).

Academic review

Manikyamba, C., Upadhyay, D., & Ram Mohan, M. (2024). Archean Crustal Evolution and Craton Formation in Peninsular India: New Insights from the Singhbhum, Dharwar and Bastar Cratons. Proceedings of the Indian National Science Academy.

The Indian subcontinent first came together as a merger of five ancient landmasses like this. And it is really easy for anyone to look at any map of India and see the evidence of this ancient geological merger. Before I show you how, let's look at the geological process behind it. When the Earth first formed, it was extremely hot and the entire surface was covered in lava. Eventually, about 4 billion years ago, some parts of that surface cooled down, and the first crust — and the layer below it, called the lithosphere — began to form in these stable, cooled regions. These ancient, extremely stable pieces of rock are called cratons. Some cratons came together to form continents like Africa and South America, and five that geologists have identified came together to create the first version of the Indian subcontinent. They are named after the areas where they sit today: Dharwar, Bastar, Singhbhum in the east, Bundelkhand in the north, and Aravalli and Marwar in the north-west. Think about a train where all the coaches are coupled: whenever the engine brakes, most of the pressure is felt between the coaches as compression; when it accelerates, the forces are felt as extension. In the same way, over millions of years these stitched-together cratons felt compression or extension — creating ranges like the Aravalli between Bundelkhand and Marwar, or valleys and rifts such as the Godavari Valley between Dharwar and Bastar, and the Mahanadi Valley between Bastar and Singhbhum. Between the southern and northern cratons lies the Central Indian Tectonic Zone, home to the Satpura Range, the Vindhya Basin, the Narmada Valley, and more. These are the clues, visible on a map of India today, to this ancient geological suture. I hope you found it interesting.

Key terms

Sources & further reading

Start here — free & accessible

The textbook

Academic review

Background reading

The world's largest foreland basin built the Indo-Gangetic Plain 🏔🌾

Tiny Sikkim packs some of Earth's densest biodiversity 🏔🌿

Gondwana means “the Forest of the Gonds” 🌏🌳