The study of gross α and β activities of samples collected from different locations between Thenkapattanam and Periyavilai, spanning across a distance of 6 km indicate wide variation in their activity. Thenkapattanam beach sands recorded maximum activity, the values are lowest in the samples collected along the Periyavilai beach. An examination of the activities of different size fractions of the beach sands has established the presence of the maximum quantities of fine samples of heavy minerals in the finest fraction. The highest α-activity of sand samples is recorded in Thenkapattanam beach and the lowest α-activity is recorded in Periyavilai. The highest β-activity of soil samples are observed in Thenkapattanam station and the lowest β-activity of soil are samples observed in Periyavilai station