A beach terrace, also known as a raised beach, coastal terrace, or perched coastline, is a relatively flat, horizontal, or gently sloping surface of marine origin that was once an abrasion platform but has since been uplifted out of the reach of wave action.
Here's a more detailed explanation:
- Formation: Beach terraces are formed when sea levels drop or landmasses are uplifted due to tectonic activity. This exposes the former seabed to the air.
- Original Function: Before being raised, the surface was an abrasion platform, a flat area carved by wave erosion at the shoreline. Waves grind rocks and sediments against the coast, slowly wearing it away.
- Upliftment: Geological processes like tectonic uplift raise the coastline, lifting the abrasion platform above the current sea level.
- Appearance: These terraces appear as flat, step-like features along the coast. They can extend for significant distances along the shoreline.
- Composition: The terrace surface typically consists of marine sediments, such as sand, gravel, and shells, which were deposited during its time as a beach.
- Significance: Beach terraces provide valuable insights into past sea levels and tectonic activity in a region. Geologists study these features to reconstruct the history of coastal landscapes and understand the processes that shape them.
- Example: Classic examples of beach terraces can be found along the California coast and in other tectonically active regions worldwide.
