Ambalappuzha coast in central Kerala is well known for persistent occurrence of mud bank at Purakkad.The results of the investigation carried out during July - December 2000 on sediment characteristics of Purakkad mud bank shelf,surrounding shelf of Ambalappuzha outside the mud bank and the shelf of the backwater outlet at Thottappally are reported. Considerable variations in sediment composition in relation to the environmental conditions were observed.Fine-grained particles in the mud bank shelf were the maximum during the active phase of mud bank. The mud bank shelf sediment was quite distinctive from the intertidal sediments outside the mud bank area, in having much higher values of organic matter, pH, chloride, sulphate and alkalinity, but with low phosphate content.

Intertidal zone, mud bank, backwater outlet, sediment