Evidence for Seawater Retreat With Advent of Meghalayan Era (∼4200 a BP) in a Coastal Harappan Settlement

Abstract

AbstractThe transformation of mature (urbanized) phase of the ancient Indus civilisation between ∼4200 and 3800 years Before Present (yr BP) overlaps with the beginning of the Meghalayan Age (∼4200 ± 100 yr BP). Though exact cause(s) for decline of urbanized Indus phase are not yet clear, researchers continue to debate whether monsoonal dryness was the sole cause or several other regional factors manifested in a compounding manner. Here, we show a regional relative sea level fall in the downstream area of Indus habitation (south‐western Gujarat region) which initiated at 4150 ± 230 and continued up to 3625 ± 200 yr BP. We provide a multi‐proxy (chronological, sedimentological, mineralogical, isotopic and elemental abundance) data set from a well‐dated vertical sediment trench from Lothal (ancient dockyard area of Indus era) to support this inference. Chief proxies used for inferring the relative sea level fall were bulk sediment carbon and sulfur contents along with their stable isotopes (δ13C and δ34S) and foraminiferal assemblage. The conspicuous shifts in majority of proxies hint at a lowering of sea stand at the regional level that likely dried this ancient Harappan dockyard (used for sea trade). Findings of our study possess implications for Holocene climate changes and their plausible impact(s) on Harappan trade and culture. Additionally, it invites evidences for large scale geological changes at ∼4200 yr BP distinct to the Meghalayan era.