Which of the following coastal landforms is primarily formed by the erosional action of sea waves?

Introduction / Context:
Coastal landforms are shaped by both erosion and deposition due to the action of sea waves, currents and tides. Understanding which features are formed by erosion and which by deposition is a core concept in physical geography. This question asks you to identify the coastal landform that is mainly a product of wave erosion, rather than deposition.

Given Data / Assumptions:

• The options include several common coastal features: cave, beach, spit, barrier island and sand bar. • We must identify which one is formed primarily by erosion. • Others are typically associated with deposition of sediments.

Concept / Approach:
Wave erosion occurs when strong waves continuously attack rock along the shoreline, cutting into cliffs and headlands. Over time, this process can hollow out weak zones in the rock, forming sea caves. In contrast, beaches, spits, barrier islands and sand bars are all depositional features, created as waves and currents deposit sand and other sediments along the coast. Therefore, the only option that clearly represents an erosional landform is the cave.

Step-by-Step Solution:
Step 1: Consider how a sea cave forms. Waves repeatedly strike a rocky headland, exploiting cracks and weak layers, and gradually hollow out a cavity. Step 2: Recognise that this process involves removal of rock material, which is characteristic of erosion, not deposition. Step 3: Examine how a beach forms. Sand and pebbles are deposited along the shore where wave energy decreases, building up a depositional feature. Step 4: Understand that spits, barrier islands and sand bars are also the result of sediment being carried by longshore currents and deposited where conditions allow. Step 5: Since only caves are produced mainly by the erosive power of waves, choose Cave as the correct answer.

Verification / Alternative check:
Textbook diagrams of coastal erosion show headlands with features such as sea caves, arches and stacks that develop as erosion progresses. These are clearly labelled as erosional landforms. On the other hand, beaches and spits appear in sections about coastal deposition. This separation in standard teaching material confirms that caves belong to the erosional group, while the other listed features are depositional.

Why Other Options Are Wrong:
Beach: Formed by the accumulation of sand, gravel and pebbles deposited by waves along the shoreline. Spit: A narrow ridge of sand or shingle extending from the coast into the sea, built by longshore drift and deposition. Barrier island: An elongated offshore island formed by the build up of sand due to wave and current deposition. Sand bar: A submerged or partly exposed ridge of sand deposited by waves and currents, often parallel to the shore.

Common Pitfalls:
A frequent error is to assume that any landform located near the sea must be depositional, especially if it is made of sand. Students may also misunderstand the term cave, thinking of it as a general underground feature instead of recognising the specific process of sea wave erosion on coastal cliffs. To avoid such confusion, always connect caves at the coast with strong wave attack on headlands, and relate beaches, spits and bars to the deposition of loose sediments.

Final Answer:
The coastal landform primarily formed by wave erosion is the Cave.