Holocene Biostratigraphic Zones Corresponding Litho-Chronostratigraphy, Environment of Deposition and Successive Changes in the Geomorphology of Bengal Basin, India during Last 10,000 Years

Biostratigraphic Zones Bb. Bz. H. I-V distinguished in C14 dated Peat, peaty clay sediments above arid, Barren zone have identified distinct environment of deposition as fresh water mixed brackish water to shallow marine to brackish water mangrove swamp, brackish water mixed fresh water swamp followed by colonization of non-littoral species to fresh water swamp during Holocene in the Bengal basin, India in chronological succession. The successive phases of depositional environment have identified the events of sea level rise, marine transgression and sea ward movement of the sea. The unique database has explored successive changes in the geomorphology of South Bengal from upland dry to marine deltaic environment to fresh water upland condition.

Plant Remains from an Archaeological Site as Indicators of Vegetation and Agricultural Practice Between(3 320±400) and(2 080±80) yr BP in Gangetic West Bengal,India

Diverse plant remains recovered from an archaeological site of Chslcollthlc-Early Historic age in the Bhalrabdanga area of Pakhanna （latitude 23°25′N, longitude 87°23′E）, situated on the west bank of the Damodar river, Bankura district, West Bengal, India, include food grains, wood charcoals, and palynomorphs. Radiocarbon dating of the recovered biological remains reveal the age of the site as （3 320 ± 400） to （2 080± 80） yr BP. The food grains were Identified as Oryza sativa L. and Vigna mungo L, and seeds of Brassica cf. campestris L. were also found; these indicate the agricultural practice and food habits of the ancient people living at Pakhanna from the Chalcolithlc to the Early Historic period. Sediments Including plant remains have been broadly divided into two zones, considering archaeological findings and radiocarbon dating. Analysis of the plant remains （I.e, wood charcoals and palynomorphs） in addition to cultivated food grains has revealed that a rich vegetation cover existed in this area, with a prevailing tropical and humid climate, comprising the timber-yielding plants Shores sp., Terminalia sp., and Tamarindus sp., with undergrowths of diverse shrubs and herbs during the Chalcolithic period （zone I） dated （3 320 ± 400） yr BP. Comparatively poorer representation and frequency of plant remains Indicate a drier climate during the Early Historic period （zone Ⅱ） dated as （2 110 ± 340） to （2 080 ± 80） yr BP. Comparisons of the archaeobotanical data recovered from the Chalcollthic and Early Historic period and also a principle components analysis Indicate a change In the climate of the area from tropical and humid at （3 320 ± 400） yr BP to tropical and drier conditions at （2 110 ± 340） to （2 080 ± 80） yr BP. The present-day tropical, dry deciduous vegetation of the area suggests that climate change has occurred in the area since the contemporaneous past. The plant remains database has been utilized to reconstruct the settlement pattern of the community living in the site between （3 320 ± 400） and （2 080 ± 80） yr BP. The community settled near the riverbank, practicing cultivation.