Final answer:
The longshore current and sediment carried by longshore drift typically run parallel to the shoreline within the nearshore zone. Cross-bedding in sedimentary layers can indicate the direction of the current, and variations in the current affect the deposition of sediments, with coarser materials closer to shore.
Step-by-step explanation:
The longshore current and the sediment transported by longshore drift typically follow a path that runs parallel to the shoreline. This phenomenon occurs in the nearshore zone, which extends from the low-tide line to where waves no longer influence sedimentation. As the waves approach the beach at an angle, they pick up sediment and carry it along the coast in the direction of the current. This process can lead to the formation of various coastal features and affects the distribution of sediments along the shoreline.
Cross-bedding is a sedimentary structure that can be indicative of the direction of wind or water flow which, in this case, helps geologists understand the path of a longshore current. The structure is noted by the deposition of sediment on the slanted side of a ripple or dune, indicating the direction the water or wind was moving. Over time, variations in this current can also create different layers of sediment, with coarser materials like sand deposited closer to the shore, and finer materials such as silt, clay, or even limestone deposited further away. This results in a gradational boundary between sediment types, keeping the layering continuous.
Nearshore environments such as coastal areas can also be dramatically affected by rivers discharging into them. When river water, carrying silt and other sediment, reaches the ocean or lake, the water slows significantly, causing silt to settle and potentially creating features such as deltas or estuarine areas, depending on the levels of silt and the action of currents or waves in the area.