Did an ancient flood contribute to Keezhadi’s abandonment?, PgII

Key Highlights:

• A study suggests that a major flood around 1,155 years ago may have led to the abandonment of the ancient settlement at Keezhadi in Tamil Nadu.
• Researchers used Optically Stimulated Luminescence (OSL) dating to analyze sediment layers covering the Keezhadi structures.
• The Vaigai River likely deposited layers of sand, silt, and clay during a high-energy flood event, burying the settlement.
• The study highlights the dynamic relationship between climate, river systems, and human settlements in the late Holocene period.

Detailed Insights:

• Keezhadi, located on the Vaigai River floodplain in Sivaganga district, contains brick structures and artifacts indicative of an "urban-like" settlement mentioned in Sangam literature.
• OSL dating of sediment samples from excavation pits KDI-1 and KDI-2 revealed burial ages spanning the last 1,200 years, with deeper layers generally being older.
• The flood event, dated to approximately 1,155 years before present, deposited coarse sand followed by fine silty-clay layers, burying the organized brick constructions and water management canals.
• Climate fluctuations during the late Holocene in the Indian subcontinent caused rivers to shift course and flood, impacting settlements dependent on river water sources like the Vaigai.
• The study differentiates between the period of habitation at Keezhadi and the time when the settlement was buried, guiding future excavation plans based on sediment accumulation rates.

Scientific/Technical Concepts Involved:

• Optically Stimulated Luminescence (OSL): A dating method that measures the energy stored in mineral grains to estimate when they were last exposed to sunlight.
• Late Holocene: A geological epoch that began around 5,000 years ago and continues to the present day, characterized by fluctuating climate conditions.
• Sedimentation: The process by which particles settle out of a fluid, such as water or air, and accumulate to form layers of sediment.