Bulletin of the Geological Society of Malaysia, Volume 16, Dec. 1983, pp. 99 – 116
1Department of Geological Sciences, The University of British Columbia, Vancouver BC, Canada
2Division of Geotechnical and Transportation Engineering, Asian Institute of Technology, Bangkok, Thailand
Abstract: The southern part of the Central Plain in Thailand is blanketed with a two part sequence here termed the Bangkok Clay. The lower part is a mixture of brown stiff clay, silt and sand which is interpreted as a deltaic-alluvial plain sequence. It is heterogeneous and cut by numerous channels reflecting drainage across the plain in Late Pleistocene and Holocene(?) time. The lower clay is separated from the upper deposit, a soft gray silty clay, by an erosional unconformity marked by paleosols and buried valleys. The upper clay is much softer and more homogeneous covering about 14,000 square kilometers of the lower plain. It contains marine fossils which suggest it was deposited in from 20 to 50 meters of water. The deposit may be the result of the Flandrian transgression of Holocene time. Its environment of deposition is inferred to be a delta front (slope) where periodic slumping occurred. The upper 2-4 meters of the soft clay is weathered and altered to a mottled reddish grey crust. This soft clay emerged from the Holocene sea approximately 3,000 B.P.