The Deccan Plateau

A Triangular Tableland

• Shape: a triangular tableland, covering peninsular India. It’s boxed in by the Vindhya Range, the Western Ghats, and the Eastern Ghats.
• Size: it spans roughly 422,000 square kilometres — about 27.7% of India’s total landmass.
• Which way it tilts: gently from west to east. Its major rivers — the Godavari, Krishna, and Kaveri — all follow that tilt, flowing east into the Bay of Bengal.

Worked example: picture tipping a giant tray very slightly, with its high edge in the west. Any water poured on it runs toward the low edge. That’s exactly why India’s biggest peninsular rivers all end up in the Bay of Bengal, not the Arabian Sea.

Built from Lava, Not Folded Rock

• Origin: most of the plateau’s surface comes from the Deccan Traps. These are layers of solidified lava, erupted around 66 million years ago.
• Thickness: those lava layers run more than 2,000 metres thick in places. They once covered a far larger area, before erosion wore them back.
• Why it’s different: unlike a fold mountain, this plateau wasn’t pushed up by colliding plates. It’s a solid mass of hardened lava, from one of the largest volcanic events Earth has seen.

Worked example: compare this to the Himalayas, built by two plates crashing together and crumpling the land upward. The Deccan Plateau formed the opposite way — molten rock poured out flat, layer after layer, then hardened in place.

Half of India, Once

• Scale then vs. now: the Deccan Traps rank among the largest volcanic provinces on Earth. Before erosion and plate movement shrank it, the original lava-flow area may have covered roughly 1.5 million square kilometres.
• Picture it: that original footprint was close to half the size of modern India — all poured out from the same volcanic event that built the plateau standing today.

Worked example: imagine a lava flow big enough to bury an area from Delhi to well past Hyderabad, all at once. Erosion and shifting plates have since worn that footprint down, to under a third of its original size. Even today’s shrunken plateau still covers over a quarter of India.

The Soil This Lava Left Behind

• The soil: the plateau’s black regur soil comes directly from this basalt. It weathers slowly into some of India’s most fertile cotton-growing land.
• Where: the plateau covers parts of eight states, chiefly Maharashtra, Telangana, Andhra Pradesh, Karnataka, Kerala, and Tamil Nadu.

Worked example: the same lava once buried this land, 66 million years ago. That’s why cotton farmers in Maharashtra today have such dark, moisture-retentive soil under their feet. Rock slowly broke down into farmland, over an almost unimaginable span of time.

A Volcano and a Mass Extinction

• The timing: the Deccan Traps eruption coincides almost exactly with the Cretaceous-Paleogene boundary. That’s the mass extinction that wiped out the dinosaurs.
• The debate: scientists still argue over the real driver. Was it the Chicxulub asteroid impact? The Deccan Traps’ volcanism? Or some real combination of both?
• One mechanism: sulphur dioxide released by the eruptions may have cooled the planet by as much as 2°C. That would have added to the extinction pressure alongside the impact.
• A wrinkle in the timeline: some studies date the eruptions in fast pulses. At least one major pulse may have happened even before the Chicxulub impact struck.

Worked example: picture two catastrophes hitting Earth within a geologically short window. One is a giant asteroid strike. The other is a volcanic eruption large enough to blanket half a continent. Scientists are still working out how much each one contributed to the mass extinction that followed.

A Plateau Still Shaping Life on It

• Then: a volcanic event 66 million years ago decided what soil this land would eventually have.
• Now: that same basalt-derived black soil still decides what farmers here can grow, and how much water their fields actually need.

The Water Running Out Beneath It (2026)

• The data: Central Ground Water Board data for June 2026 showed groundwater declining in 17 of Telangana’s 33 districts. That’s part of the Deccan Plateau’s black-soil belt. (Source: Deccan Chronicle)
• The worst hit: Hyderabad recorded the sharpest single-district drop — 2.47 metres in one month. That happened even after a wetter-than-usual June. (Source: Deccan Chronicle)
• Why it matters here: the plateau’s basalt rock doesn’t hold groundwater the way sedimentary rock does. Heavy extraction here recovers far slower than in India’s alluvial plains.