Weathering and soils

Weathering is the physical disintegration and chemical decomposition of rocks in situ at or near the earth’s surface by climatic and biological elements. Due to the prevailing high temperature, abundant rainfall and high humidity in Singapore, chemical weathering is intensive, producing a surface regolith. The thickness of this regolith is variable and as much as 40 m has been observed at Seletar.

Weathering is also an important process in soil formation, which is a complex function of the local climate, geology, physiography, biota and time. In Singapore, soils have mainly been formed by the intense chemical weathering of igneous and sedimentary rocks. Under equatorial conditions, geological and physiographical factors effectively control the process of soil formation. Igneous rocks weather intensely and rapidly to form well developed soils. The products of weathering on the igneous rocks vary with differences in mineral composition and structure. Deep weathering is also characteristic of soils developed over igneous rocks in Singapore. For sedimentary rocks, weathering and soil formation is not as advanced when compared to the igneous rocks.