The Deccan Traps are a large igneous province located on the Deccan Plateau of west-central India (between 17–24N, 73–74E) and one of the largest volcanic features on Earth. They consist of multiple layers of solidified flood basalt that together are more than 2,000 m (6,562 ft) thick and cover an area of 500,000 km2 (193,051 sq mi) and a volume of 512,000 km3 (123,000 cu mi). The term 'trap', used in geology for such rock formations, is derived from the Dutch word for stairs,  referring to the step-like hills forming the landscape of the region.
The Deccan Traps formed between 60 and 68 million years ago, at the end of the Cretaceous period. The bulk of the volcanic eruption occurred at the Western Ghats (near Mumbai) some 66 million years ago. This series of eruptions may have lasted less than 30,000 years in total.
The original area covered by the lava flows is estimated to have been as large as 1.5 million km², approximately half the size of modern India. The Deccan Traps region was reduced to its current size by erosion and plate tectonics; the present area of directly observable lava flows is around 512,000 km2 (197,684 sq mi).
The release of volcanic gases, particularly sulfur dioxide, during the formation of the traps contributed to contemporary climate change. Data point to an average fall in temperature of 2 °C in this period.
Due to the volcanic gases and subsequent temperature drop, the formation of the traps is seen as a major stressor on biodiversity at the time. This is confirmed by a mass extinction topping 17 families per million years (about 15 families per million years above the average). Sudden cooling due to sulfurous volcanic gases released by the formation of the traps and localised gas concentrations may have been enough to drive a less significant mass extinction, but the impact of the meteoroid that formed the Chicxulub Crater (which made a sunlight blocking dust cloud that killed much of the plants, called an impact winter) made this one of the most pronounced mass extinctions in the Phanerozoic.
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