Regional coastlines

Coastlines are classified into two main types based on geological structure: Concordant and Discordant.
Concordant coastlines are those where the layers of rock are parallel to the direction of the coastline. This can lead to the formation of features such as coves and lagoons.
Swanage Bay is a key example of a concordant coastline. The less resistant layers of clays and sands have been eroded to form a bay, with more resistant chalk forming a headland.
Discordant coastlines have layers of rock that are perpendicular to the direction of the coastline. The softer rock is eroded more quickly, leading to the formation of alternating headlands and bays.
The Dorset coastline in south England is an example of a discordant coastline, as it has this alternating pattern of headlands (chalk) and bays (clay and sands).

Coastlines can be further categorized as emergent or submergent.
Emergent coastlines are formed when the land rises relative to sea level. This can result from tectonic activity or isostatic rebound following the retreat of ice caps.
One example of an emergent coastline is the Moray Firth coastline in Scotland. Raised beach platforms here are evidence of post-glacial uplift.
Submergent coastlines, on the other hand, are formed when sea level rises relative to the land. Key features of these are rias and fjords.
The Dalmatian Coast in Croatia is famous for its rias – drowned river valleys – a classic feature of a submergent coastline.

Tidal range can greatly influence coastal processes. For instance, high tidal ranges enable strong tidal currents which are capable of eroding and transporting large amounts of sediment along the coast.
Tides also directly influence the development of coastal landforms;, with ebb and flow causing daily changes in water levels.

Salt marshes are coastal wetlands that are flooded and drained by salt water brought in by tides. They are characterized by halophytic (salt tolerant) vegetation like cordgrasses.
Mangrove swamps are found in tropical and subtropical tidal areas. The mangrove trees have special adaptations to survive in these harsh coastal conditions. They act as natural barriers, reducing coastal erosion and providing habitat for diverse wildlife.
Coral reefs are complex marine ecosystems found in warm, shallow waters. They are vulnerable to external threats such as climate change, ocean acidification and human activities.

Note: Always be aware of how geographical context and differences in geological composition can shape regional coastlines and the types of features that form as a result.