The Deccan Traps are a large igneous province located on the Deccan Plateau of west-central India (17°–24°N, 73°–74°E) 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, cover an area of 500,000 km2 (193,051 sq mi) and have a volume of 512,000 km3 (123,000 cu mi). Originally, it may have covered 1.5 million km2.
The term "trap" has been used in geology since 1785–95 for such rock formations. It is derived from the Scandinavian word for stairs ("trappa") and refers to the step-like hills forming the landscape of the region.
The Deccan Traps began forming 66.25 million years ago, at the end of the Cretaceous period. The bulk of the volcanic eruption occurred at the Western Ghats 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 sulphur dioxide, during the formation of the traps contributed to contemporary climate change. Data points to an average drop in temperature of 2 °C in this period.
Because of its magnitude, scientists formerly speculated that the gases released during the formation of the Deccan Traps played a role in the Cretaceous–Paleogene (K–Pg) extinction event (also known as the Cretaceous–Tertiary extinction). It was theorized that sudden cooling due to sulfurous volcanic gases released by the formation of the traps and localised gas concentrations may have contributed significantly to the K–Pg, as well as other mass extinctions. However, the current consensus among the scientific community is that the extinction was triggered by the Chicxulub impact event in North America (which would have produced a sunlight-blocking dust cloud that killed much of the plant life and reduced global temperature, called an impact winter).