Beach Sediments Essay Example | Topics and Well Written Essays - 2000 words

Beach Sediments - Essay Example Some beaches are built to great widths by sediments washed to the sea by episodic floods, gradually eroding until the next major flood replenishes the sand ("Beach Formation and Types of Beaches and Sand"). Beach sediments are delivered per year in million cubic yards through longshore transport. Different beaches have different colors and textures because of the various sediments that make them up. There are beaches made up of eroded shale cliffs, multicolored agates ground and polished by the surf, feldspar minerals, ground quartz, and even iron minerals. The various make up of the sediments determine the origin of these sand beaches which help researchers know more information about a particular coast. Mechanical sediments, also known as clastic sediments, came from the erosion of oceanic rocks formed during the earlier times. These sediments are carried by streams or waves to the place where they are deposited. Ocean sediments, especially in the form of turbidites, are usually carried over and deposited at the bottom of continental slopes ("The Columbia Encyclopedia" 42907). Chemical reactions in seawater form chemical sediments which results in the precipitation of small mineral crystals that settle to the floor of the sea and finally form a chemically pure layer of sediment somehow. Organic sediments are formed from plant or animal actions. ... There are also some traces of windblown volcanic and continental dusts found in organic sediments. Properties of Sediments Sediments have different properties which are being studied by researchers for different purposes such as coastal engineering. One property of sediments is its physical form. Sediments can be loose, fluid, hard or firm. Examples of loose sediments are sand and silt; mud is a form of fluid sediment. There are also sand forms that are firm and stiff as clay. Hard sediments are those rocks and coral pieces that can be found in some beaches. Sediments can also be classified in terms of their cohesiveness. Sediments can be cohesive, non-cohesive or mitigated. Sediments such as clay and firm sand are highly cohesive as each particle stick closely together. Mud and loose sands, as well as rocks and other loose particles, are non-cohesive. Mitigated sediments are mainly non-cohesive sediments with a little mix of clay. Non-cohesive sediment behavior in water is mainly controlled by mechanical forces. The hydrodynamics of a particle refer to its ability to remain still or become entrained if on the bed surface, or to remain in suspension or to cease movement if in motion ("Sedimentation Investigations of Rivers and Reservoirs" 7-1). The properties that crucially affect the non-cohesive particle's hydrodynamics are its size, shape and specific gravity. The behavior of cohesive sediments, on the other hand, is controlled by electrochemical forces and dependent on the particle size, sediment mineralogy, and water chemistry. Particle size is considered to be the most important property of non-cohesive sediments. The size of the particle can be defined by any of the four methods: a) Nominal diameter - with this