Submergent coastline
Coastlines drowned by relative sea level rise.
When sea levels rise relative to the land, the ocean floods coastal areas, creating what are known as submergent or drowned coastlines. This change can come from isostasy or eustasy. These coastlines contrast with emergent ones, where sea levels fall relative to the land. Many submergent coastlines appeared at the close of the Last Glacial Period, as melting glaciers raised global sea levels and altered local land heights.
Quick Facts
- Opposite landform
- Emergent coastline
- Major formation period
- End of the Last Glacial Period
Facts from the source article.
Formation
Submergent coastlines form when sea level rises or land level falls, driven by isostatic or eustatic change. Isostatic change may result from post-glacial adjustment or tectonic action such as earthquakes or volcanic eruptions causing land subsidence. Eustatic sea level rise can be caused by thermal expansion, where warmer water increases in volume, leading to global sea level rise.
Common features
Features include rias, which are drowned river valleys flooded by the sea, often with a widening funnel shape and increasing depth toward the coast, causing exaggerated tidal effects. Fjords are drowned glaciated valleys, or U-shaped valleys, flooded by the sea. Dalmatian coasts consist of long narrow islands parallel to the coast, separated by narrow sea channels called sounds, named after the Dalmatia region of Croatia.
Examples
Notable examples include Western Norway, with many fjords from sea level rise at the end of the LGP; the Western Coastal Plains of the Indian subcontinent, including the Narmada and Tapti River estuaries; Southern England and South Wales, with rias such as Falmouth Harbour and Milford Haven; the Dalmatian coast; and Port Jackson (Sydney Harbour) in Australia, a ria.
More in Coastal Landforms
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