cohesive and non-cohesive materials are always coexists in rivers whether on bank or bed. The presence or absence both of them afftect on river mrphology due to different characteristics on erosion process.However, this effect is simplified by many scientists especially the effect of cohesive material. Many numerical analysis and experimental studies have developed to study the evolution of channel. Most of them use non-cohesive material and ignore the presence of cohesive material. The experiments of bank erosion charecteristic using cohesive and non-cohesive layers were conducted. Three types of bank are used in thise research. First type is the bank that composed of non-cohesive material layer. Second type is the bank that composed of cohesive and non-cohesive material layer. Third type is the bank that composed of cohesive material layer. The results show that mass failure mechanism occurs in case bank composed cohesive layer on the top and non-cohesive layer at the bottom. Some of the failed blocks shelter near the bank toe. The local scouring occurs at around the failed block and a part of them remain for a long time on the bed near the bank toe. This phenomenon is very important because most of scientists ignore this phenomenon in numerical calculation and it assumed flush away with flow