Final answer:
If the longshore drift can carry away only a portion of sediment deposits, it leads to the formation of spits or other coastal landforms like barrier islands. These features are created by the remaining sediment that is not transported away and reflect the interaction of coastal processes and sediment deposition.
Step-by-step explanation:
When discussing coastal processes, longshore drift plays a key role in the transportation of sediments along the shore. This process can result in various geological features, depending on how much sediment is removed or deposited. If longshore drift can carry away only a portion of the sediment deposits, while the remainder is left behind, this can lead to the formation of spits or other coastal landforms. A spit is an extended stretch of beach material that projects out to sea and is joined to the mainland at one end. Other features such as barrier islands can also be formed under similar processes. Moreover, the composition and structure of these deposits may vary, with sand being deposited closer to shore and finer sediments like silt and clay settling further away, leading to the formation of layered sedimentary structures with a gradational boundary.
The area of deposition can also create specific sedimentary structures. For example, cross-bedding occurs in dunes and ripples, indicating the direction of wind or water flow. Load casts may form when heavier sediment overlays lighter, water-saturated sediments, generating bulb-like impressions. In the context of rising sea levels or transgression, the deposition of sediments shifts towards the coastline, leading to onlapping patterns in the geological record. Such vertical changes in the rock record reflect horizontal changes in the environment, also explained by Walther's Law. If sediment is deposited in a non-flat manner, such as on continental margins, it leads to the creation of clinoforms. This all illustrates the dynamic interplay between the deposition of sediment and coastal geomorphology.