The longshore transport of sediment along a shoreline, driven by oblique waves, is known as what?

• A. Groin
• B. Lagoon
• C. Longshore Drift
• D. Moraine

Answer: (C)

Longshore drift describes the movement of sediment along the shore caused by waves arriving at an angle to the coastline. When waves break obliquely, the swash moves material up the beach diagonally while the backwash returns straight down the shore, creating a longshore current in the surf zone. This combination transports sediment along the coast in a zigzag path, gradually shifting sand and gravel along the shoreline over time. Structures like groins aim to trap this sediment, lagoons are bodies of water behind barriers, and moraines are glacial deposits, so they’re not the process of along-beach transport.