Which process is essential in the formation of beaches in bays?

The formation of beaches in bays is primarily driven by the process of deposition. This occurs when sediments, such as sand and gravel, are transported by waves and currents and eventually settle along the shoreline. In a bay, the calm waters often allow finer materials to be deposited, creating a sandy beach. The shape and features of the bay can further influence how wave energy is dissipated, which enhances the deposition process.

In contrast, erosion, abrasion, and hydraulic action are primarily associated with the wearing away of landforms rather than the accumulation that creates beaches. Erosion tends to remove material from shores and cliffs, while abrasion involves the grinding action of sediment against rock surfaces. Hydraulic action refers to the force of water impacting rock, leading to their fracturing and erosion. These processes do not contribute to beach formation in the same constructive way that deposition does.