Submergent Coasts:
Submergent coasts are formed when the sea level rises relative to the land, causing the land to be submerged. This can occur due to various factors such as global sea-level rise caused by climate change, tectonic subsidence (sinking of the land due to geological processes), or a combination of both.
Characteristics of Submergent Coasts:
- Drowned Landscapes: Submergent coasts often display drowned landscapes, where previously terrestrial features such as hills and valleys are now submerged beneath the water.
- Estuaries and Bays: As the sea level rises, river mouths and valleys that were once above water become flooded, forming estuaries and bays. These sheltered bodies of water are important ecosystems for various marine life.
- Barrier Islands and Lagoons: In some cases, long, narrow islands known as barrier islands form offshore, creating lagoons between the islands and the mainland.
- Coastal Wetlands: Submergent coasts are often associated with coastal wetlands, such as salt marshes and mangroves, which thrive in the brackish water conditions.
Emergent Coasts:
Emergent coasts are formed when the land rises relative to the sea level, causing previously submerged areas to emerge above water. This can occur due to tectonic uplift (raising of the land due to geological processes), a drop in global sea level, or both.
Characteristics of Emergent Coasts:
- Coastal Plains and Terraces: Emergent coasts often feature coastal plains or terraces, which are flat landforms that were once submerged but have risen above the water.
- Cliffs and Wave-Cut Platforms: The rising land exposes cliffs that have been carved by wave erosion when the sea level was higher. In front of these cliffs, wave-cut platforms can be seen, which are relatively flat, eroded surfaces at the base of the cliffs.
- Raised Beaches: As the land rises, former beaches and marine deposits can be found above the present sea level, forming raised beaches.
The distinction between submergent and emergent coasts is essential in understanding the coastal processes, morphology, and ecosystems that characterize these regions.
