Final answer:
Sea cliffs are a clear indication of wave erosion on rocky coasts, resulting from the powerful and persistent action of ocean waves against the shore. Other features like sea arches and stacks also signify wave erosion and the dynamic coastal environment.
Step-by-step explanation:
Wave erosion on rocky coasts can create various landforms, with sea cliffs being a classic example of such erosion. When ocean waves relentlessly crash against coastal rocks and cliffs, the energy from these waves leads to the mechanical wearing away of the rock, a process referred to as erosion. Over time, this continuous action can result in significant geological structures such as sea cliffs, sea caves, arches, and stacks.
Sea cliffs are the most direct evidence of wave erosion. These steep rock faces are formed by the destructive power of the waves, which continually pound against the shore, eroding it vertically. Another landform created by wave action is the sea arch, formed when waves erode a cliff from two sides, eventually breaking through and leaving a bridge of rock over the water. If an arch collapses, it leaves behind a stack, an isolated pillar of rock. All these features are indicative of high-energy environments and the power of wave erosion on coastal landscapes.