Clastic sedimentology is one of the emerging fields under the broad band of Sedimentology and Stratigraphy. The control of tectonic and chemical weathering on the composition of fluvial sands in tropical environment is investigated to know the extent to which chemical weathering obscures tectonic information in tropical environment. This study focuses on the effect of differential climate and physiography on the texture, mineralogy and chemistry of fluviatile and beach sediments from the southern part of Indian subcontinent where diverse climate and weathering condition exists, albeit a common source viz., the Western Ghats (south of 10ø N Latitude). All sedimentological attributes of detrital sediments are investigated and explored to interpret the factors controlling the genesis. A vivid summary of the similar works over the world also is included. Utility of both light detrital fractions and heavy minerals in the interpretation of climate and tectonics of ancient analogues is also explored. This work underscores the dictum that ?tectonism represents the broad strokes of the sandstone mineralogic brush; but climate provides the superimposed detail?.