A lava flow the size of France once buried much of peninsular India. This article covers the Deccan Traps, and their disputed role in wiping out the dinosaurs.
✊ Must Know
What the Deccan Traps Are
- The Deccan Traps are a massive volcanic flood-basalt province, formed by repeated lava flows.
- They cover roughly 500,000 sq km today. Erosion has shrunk them from an original extent of about 1.5 million sq km.
- The basalt layers reach up to 2 km thick in places. They spread across Maharashtra, Madhya Pradesh, Gujarat, Karnataka, and parts of Andhra Pradesh.
- Eruption began around 66 million years ago, right at the boundary between the Cretaceous and Paleogene periods.
- This K-Pg boundary marks the mass extinction that wiped out the non-avian dinosaurs.
📘 Good to Know
Scale and Formation
- The main eruptive pulse lasted roughly one million years. It ran from about 0.3-0.4 million years before the K-Pg boundary to about 0.7 million years after it.
- Total erupted magma volume exceeded a million cubic kilometres, among the largest flood-basalt events in Earth’s history.
- Weathering of this same basalt over millions of years produced the fertile Black (Regur) Soil found across much of the Deccan Plateau today.
Test Yourself
🌟 Great to Know
Legacy in Soil and Landscape
- Scientists still debate whether the Chicxulub asteroid impact or Deccan volcanism caused the mass extinction. Both events occurred at almost exactly the same time, roughly 66 million years ago.
- Different dating methods have produced conflicting eruption sequences. Some studies place the main eruptions after Chicxulub; others find major pulses beginning before it.
- A single volcanic event shaping both an ancient mass extinction and modern agricultural soil shows how deep-time geology still has visible, present-day consequences.
- The scale mismatch between the Traps’ original 1.5 million sq km extent and today’s 500,000 sq km shows how much erosion can remove, even from a colossal geological feature.
📝 Previous Year Questions
UPSC Mains 2022 GS Paper I, Q6
Where Black Cotton Soil Comes From
- The fact Black cotton soil (regur) forms from the weathering of fissure volcanic rock — the basalt of the Deccan Traps themselves.
- See also The full story of this soil’s properties and distribution is covered in IndGeo0014 — Black (Regur) Soil of India.
- Answer: (b) Fissure volcanic rock.
- View this question on the full 2021 paper →
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