Deccan Traps

The Deccan Traps are a continental flood-basalt province in west-central India. Their name refers to the step-like appearance of many exposed lava layers: the word ‘trap’ derives from a term for stairs. The preserved province spans roughly 500,000 square kilometres, while geological studies indicate its original extent was larger, with some areas later eroded or concealed beneath younger deposits or the sea. The Western Ghats preserve particularly thick and well-studied sections.

The province consists chiefly of many superposed basalt flows produced by repeated eruptions. Individual flows and their boundaries can be mapped and compared using field relationships, rock composition and other geological evidence. In the Western Ghats, researchers distinguish a succession of named formations grouped into the Kalsubai, Lonavala and Wai subgroups. The volcanic rocks are not uniform everywhere: flow types, mineral composition, intrusive rocks and associated structures vary across the province.

The main Deccan eruptions occurred around the Cretaceous–Paleogene transition, approximately 66 million years ago. Dating work using uranium–lead analyses of zircon-bearing material has resolved multiple high-volume eruptive intervals, including activity before and after the boundary. Volcanic emissions could have affected climate and ecosystems, and research considers Deccan volcanism alongside the Chicxulub impact when examining the mass extinction. The relative contributions and environmental pathways remain active scientific questions; temporal association alone does not establish a single cause.

The Deccan Traps provide an unusually extensive record for studying large igneous provinces, basalt emplacement, geochemistry and geochronology. Their stratigraphic sections preserve clues to eruptive sequences and intervals between flows. The region is also a notable geological landscape: weathering and erosion have shaped its plateau and escarpments, while basalt has influenced local landforms, soils and groundwater.