Indian Volcanic Eruptions That Kill The Dinosaurs

The Deccan Traps: The Volcanic Eruptions That Helped Kill the Dinosaurs

The Deccan Traps are one of the largest volcanic provinces on Earth. Formed around 66 million years ago, the eruptions released massive lava flows and gases that affected global climate — and played a major role in the mass extinction at the end of the Cretaceous (the K–Pg event) when the non-avian dinosaurs disappeared.

1. What are the Deccan Traps?

The Deccan Traps is a giant region of layered basalt lava flows located mainly across Maharashtra, Madhya Pradesh, Gujarat and parts of central India.

• Formed approximately 66 million years ago.
• Lava originally covered more than 500,000 km² (older estimates are larger) and in places is up to 2 km thick.
• The word “Traps” comes from the Swedish trappa (stair) for the step-like stacked basalts.

2. Why did these volcanoes erupt?

Most scientists link the Deccan eruption to a deep mantle plume called the Réunion hotspot. As the Indian plate moved over the plume, huge volumes of magma reached the surface and erupted as flood basalts.

3. How the eruptions affected life on Earth

Deccan eruptions were flood basalt eruptions — enormous, long-lasting outpourings of basaltic lava. They released:

• Large amounts of sulfur dioxide (SO₂) — which forms sunlight-blocking aerosols.
• Massive volumes of carbon dioxide (CO₂) — driving greenhouse warming later on.
• Volcanic ash and particulates that affected ecosystems worldwide.

Effects:

• Volcanic winter: Aerosols and ash reduced sunlight → cooling and reduced photosynthesis.
• Greenhouse warming: Elevated CO₂ caused later warming and climate instability.

4. Did the Deccan Traps kill the dinosaurs?

There are two main hypotheses for the K–Pg mass extinction:

1. Asteroid impact — the Chicxulub crater in Mexico produced global firestorms, a dust cloud, and immediate catastrophic effects.
2. Deccan volcanism — prolonged environmental stress from huge volcanic output.

Current consensus: Both events occurred around the same time (~66 Ma) and likely acted together — the asteroid may have delivered the fatal blow while Deccan volcanism had already weakened global ecosystems.

5. Evidence linking Deccan eruptions to extinction

• Geochemical markers (e.g. mercury spikes) in sediments consistent with massive volcanism.
• Precise radiometric dating shows major Deccan flows overlap the K–Pg boundary.
• Changes in marine and terrestrial fossils that coincide with lava-flow timing.

6. Importance of the Deccan Traps for India today

• Basalt weathering produced black cotton (regur) soils — excellent for cotton and other crops.
• Influences the plateau landscape and hydrology (groundwater aquifers).
• Contains important mineral deposits and shaped the topography near the Western Ghats.

Summary

Deccan Traps = giant flood basalt province in India formed ~66 million years ago by the Réunion hotspot. The eruptions released gases and ash that greatly disturbed climate and ecosystems, and together with the Chicxulub asteroid, led to the mass extinction that ended the age of dinosaurs.

MCQs for Practice

1. The Deccan Traps were formed due to:
   A. Subduction Zone    B. Hotspot Volcanism    C. Collision of Plates    D. Sea-Floor Spreading
   Answer: B
2. The K–Pg extinction happened around:
   A. 10 million years ago    B. 50 million years ago    C. 66 million years ago    D. 100 million years ago
   Answer: C
3. Black cotton soil in India is formed from:
   A. Granite    B. Sandstone    C. Basalt (Deccan Traps)    D. Limestone
   Answer: C

Internal Linking Suggestions

Origin of the Earth Interior of the Earth Climate of India Agriculture in India

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