A group of students were siting at a high steep face of a rock along the sea coast of the Indian Ocean. They observed the breaking movements of ocean waves in which ocean water is thrown up the beach and retuned under gravity down the shore.
(i)What are the two wave processes the students observed?
(ii)Mention four erosion processes involved in that ocean wave.
(i) The two wave processes observed by the students are wave breaking and wave swash.
- Wave Breaking: Wave breaking refers to the moment when an ocean wave reaches a critical height and steepness, causing the wave crest to collapse and the wave to break onto the shore. This breaking action is commonly observed along coastlines, especially in areas with steep slopes or rocky shorelines. The breaking waves produce various forms of wave action, including surging, plunging, or spilling, depending on the specific characteristics of the wave and the beach.
- Wave Swash: Wave swash refers to the movement of water up the beach after a wave breaks. When a wave reaches the shore, the energy of the wave propels the water up the beach, creating a swash. The swash is responsible for carrying sediment and debris landward and can deposit material on the beach, influencing coastal processes and landforms.
(ii) The four erosion processes involved in ocean wave action are:
- Hydraulic Action: This erosion process occurs when the force of the breaking waves compresses air into cracks and crevices in the rocks along the shore. The pressure exerted by the trapped air causes the rocks to weaken and eventually break apart. Over time, repeated hydraulic action can lead to the formation of sea caves, notches, and other erosional landforms.
- Abrasion: Abrasion refers to the wearing away of rock surfaces by the impact of sediment, such as sand and pebbles, carried by the waves. As waves crash onto the shore, they carry and move sediment, which acts as an abrasive agent. The constant grinding and rubbing action of the sediment against the rocks can result in the smoothing, shaping, and eventual erosion of the coastal landforms.
- Attrition: Attrition is the process by which sediment carried by waves or currents collides with each other, causing the particles to break down and become smaller. As waves break and the energy dissipates, sediment particles are tossed and rolled together, leading to the fragmentation and rounding of the particles. This attrition process contributes to the overall erosion and transport of sediment along the coast.
- Corrosion (or Solution): Corrosion is the chemical process by which rocks and minerals are dissolved and removed by the action of seawater. Seawater contains dissolved salts and acids that can react with certain types of rocks, such as limestone or chalk, resulting in their gradual dissolution. Over time, corrosion can create distinctive coastal features like sea cliffs, sea stacks, and sea caves.
These erosion processes, driven by the power of ocean waves, shape the coastal landscape and play a significant role in the formation of coastal landforms and the dynamic nature of coastal environments.