Geomorphology and soils of the Padang Terap District, Kedah, Peninsular Malaysia

Geomorphological and pedological field surveys were carried out m a joint program in the Padang Terap District of Kedah, Peninsul a r Malaysia. A chronose quence of landforms was esta blished and revea ls (I) remnants of an older pediplain (2) a surface comprising younger pediments (P 2), shall ow depress ions (02 ) and river terraces (T 2 ) and .(3) a most recent river terrace (TJ The evolution of the landforms is explained by a concept of changing vegetation covers, from dense forest to an open cover (e.g. sa vanna) as a response to changing Quaternary climatic condition s. Important layers of volcanic ashes were fo und in the upper part of the Padang Terap basin . Their geomorphic positi on,-on top of T 2 and eroded by T, -and th eir 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 th e soils, developed on snale and clayey alluvium·, a re markedly different on the various landforms. Their physico-chemical a nd mineralogical characteristics, and their weathering indices full y support the proposed landscape model and chronology.