Late Quaternary Sedimentary Environment and Landform Evolution in the Bengal Lowland

Abstract

The author subdivided the recent sediments and discussed the landforms and sedimentary environment in the Bengal Lowland based on the analysis of the sediments. The recent sediments are subdivided into five members, and the sealevel curve in the region is similar to so-called “Sheperd curve” with regression during a certain period between ca.12,000 and 10,000 yBP. During the maximum epoch of the last glacial age, the rivers flowing in the Bengal Lowland deposited gravels on the valley floors. After the period, the sea level rose up to about 45 m below present level, and the lower member deposited by ca. 12,000 yBP. During ca.12,000 and 10,000 yBP, the delta and flood plain surface was slightly dissected according to the regression of the sealevel. After the regression, the middle member characterized by fine sediments in the deltaic condition deposited. The upper member deposited during 10,000 (or 8,000) yBP and 6,000 (5,000) yBP. After ca. 5,000 yBP, broad peat land or wet land developed widely in the Bengal Lowland. © 1987, The Association of Japanese Geographers. All rights reserved.