Edexcel IGCSE Geography 复习笔记 2.1.3 Coastal Environmental Change

• Geology shapes the coastline over time, place and space
• A coastline made up of softer rocks such as sands and clays will be easily eroded by destructive waves to form low, flat landscapes such as bays and beaches
• Coastlines of more resistant, harder rock will take longer to erode and produce rugged landscapes such as headlands
• The differences between hard and soft rocks will also impact the shape and characteristics of cliffs

• Geology, therefore, shapes the coastline vertically through the height and profile of a cliff and horizontally with bays and headlands

• The longer a coastal landform has existed, the more likely it will be colonised by vegetation
• Over time, vegetation will 'fix' a feature (e.g. a sand dune)
• Vegetation adaptation is important in order to survive coastal conditions
• Vegetation has to cope with high levels of salt in both air and soil
• Largest influence of vegetation is to assist protect and preserve coastal landforms such as sand dunes, salt marshes and mangroves

• Rising sea levels produce submergent coastlines, with rias and fjords
• Falling sea levels produce emergent coastlines, with relic features such as raised beaches, cliffs with caves, arches etc.
• Sea levels have risen and fallen many times in the past
• During the last Ice Age, sea levels fell as the water was locked up in glaciers and ice sheets, rising again as the ice melted
• Sea levels are linked to global warming and will have a significant effect on many low lying coasts and islands
• Many Pacific Ocean islands, such as Kiribati and Tuvalu are at risk of being completely submerged by rising sea levels
• This issue is made worse as many of the world's densely populated areas are located on coastal lowlands
• New York and Miami in the US are major cities vulnerable to sea-level rise as the cities are built at sea level

Influence of People

Human Activity

• Human activities, either intentionally or not, transform the features and landscape of a coastline:
  • Settlement - coasts have always been a place of attraction and residence to people
  • Economic Development -  exploitation through fishing, farming, trade, tourism and energy production
  • Coastal Management - controlling the coastline to protect human interests
• Through any or all of the above, the natural landscapes and features of the coast can be changed, thereby changing the coastline over time, space and place