Bulletin of the Geological Society of Malaysia, Volume 20, August 1986, pp. 765 – 790
Geological Institute, State University of Ghent Krijgslaan, 281 B-9000 GENT, Belgium
Abstract: Geomorphological and pedological field surveys were carried out in a joint program in the Padang Terap District of Kedah, Peninsular Malaysia.
A chronosequence of landforms was established and reveals (1) remnants of an older pediplain (2) a surface comprising younger pediments (P2), shallow depressions (D2) and river terraces (T2) and (3) a most recent river terrace (T1). The evolution of the landforms is explained by a concept of changing vegetation covers, from dense forest to an open cover (e.g. savanna) as a response to changing Quaternary climatic conditions.
Important layers of volcanic ashes were found in the upper part of the Padang Terap basin. Their geomorphic position,-on top of T2 and eroded by T1 -and their age (75,000 y B.P. or 30,000 y B.P.) permit the postulation of an important drier climatic phase for the area in the Late Pleistocene.
The field characteristics of the soils, developed on shale and clayey alluvium, are markedly different on the various landforms. Their physico-chemical and mineralogical characteristics, and their weathering indices fully support the proposed landscape model and chronology.