The East Coast of Tamil Nadu, Chennai to Cuddalore, is a narrow sandy strip with promontories of different bedrocks such as granite, granite gneiss, charnockite and sandstone.In this work, tafoni, spheroidal weathering, weathering rind and red soil formed over different rock types have been studied. Detailed mineralogy, micromorphology and geochemical analyses supported by SEM studies indicate mineral alteration of feldspars, hornblende, orthopyroxene and micas forming clay minerals such as kaolinite and halloysite. Soil physical and chemical properties indicate physicochemical weathering accentuated by biological processes due to tropical-subtropical climate conditions. Weathering and alteration of granite, granite gneiss and the charnockite support a thin veneer of soil and bedrock alteration while the Cuddalore ferruginous sandstone have formed vertisols along the East Coast of Tamil Nadu.
