The characteristics, distribution, and accumulation of detrital sediment on the surface sediment in the Senunu Sea are used as a preliminary study to identify the detrital and sedimentation processes’ origin. This study aims to present the characters and composition of detrital sediment on Senunu seabed. It illustrates the influence of land sediment sources on sediment compositions settled on the bottom of the surrounding seas. Specific review on the sediment character in this region was done to identify surface sediment layers carrying tailings materials from ore mining on land and differentiate them from natural sediment. 53 sediment core from the Senunu bottom were collected and analyzed for their detrital characteristics using a binocular microscope. In general, sediment composition in Senunu seabed was terrigenous sediment with dominant material quartz, andesite, and tuffaceous breccia. Based on the detrital analysis, sediment lithology of natural seabed sediment and sediment containing tailing material is distinguished by color, layer contact, grain packing, grain shape, biota association, and specific mineral content quartz, mica, and magnetite. Surface sediment containing tailing material had more quartz mineral, had more similar grain size and crystal shape, fresher mineral condition, clearer color, and looser grain relation than seabed sediment that did not contain tailings material.. Based on the different characters and distribution patterns, sediment carrying tailings in the Senunu seabed. Based on the other characters and distribution patterns, sediments carrying tailings in the Senunu seabed on average were 2-167 centimeter thick at the surface with accumulated tailing 1-50% of total sediment at the sea bottom. Furthermore, the distribution of these tailing deposits is influenced mainly by morphodynamic, hydrodynamic conditions and the process of redeposition.

Tectonic processes and high energy waves, tidal phases, generally formed the coasts of southern Java. The grain size of the beach is generally gravel, and large stones. Some pristine beaches consist of pebbly, rocky, sandy beaches or a mixture of sand, gravel, and rocks / boulders. Steep gravel beaches are always associated with coastal erosion. On the other hand, a beach with pebbles and boulders can be a stable natural defense. This location is a preservation of various fossil markers of sea level change and also as a habitat for marine life. A study on geomorphology and sediment types was carried out around the coast of Pameungpeuk, South West Java in May 2016. The purpose of this study was to demonstrate the importance of gravel beaches as natural protection in maintaining stability of coastal habitats and as a barrier from high waves. On the other hand, sandy beaches are highly susceptible to erosion. Exposure to gravel and boulders in front of the beach can act as a barrier to erosion from the beating of waves. Pameumpeuk beach and its surroundings are also a habitat for lobsters because many rock structures are found with holes and their position behind the rock barrier as natural protection.