Coastlines and Coastal Processes

Primary Coastal Processes

• Rivers, Waves, Tides, Relative sea level change

Types of Coastlines

• Submergent Coastline: Rising sea level relative to the coastline (e.g., mid-latitude east coast U.S.)

  • Causes: Climate warming, land subsidence, water displacement

• Emergent Coastline: Falling sea level relative to the coastline (e.g., high latitude east & west coast U.S.)

  • Causes: Climate cooling, land uplift

• Static Coastline: Stable sea level

  • Rate of rise = rate of uplift; rate of fall = rate of subsidence

Coastline Comparison

• Active Continental Margin (West Coast): High relief, tectonic activity, narrow continental shelf

• Passive Continental Margin (East Coast): Low relief, non-tectonic, broad continental shelf

Sea Level Changes

• Global sea level rise since the last ice age due to melting glaciers

• Modern ice caps melting at accelerated rates due to anthropogenic global warming

Estuaries

• Formed from submerged river channels, protected from strong waves

Emergent Coastlines

• Characterized by high relief and tectonic uplift

• Narrow continental shelf, rocky coastlines with unique landforms

Erosion Features on Rocky Coasts

• Wave-cut notches and platforms

• Erosion leads to features such as headlands, embayments, sea stacks, arches

Wave Refraction

• Waves bend around headlands, causing focused erosion at headlands and deposition in bays

Isostatic Rebound

• Uplift of coastlines in the northern hemisphere due to melting ice sheets (Pleistocene)

• Faster rebound in areas where ice was thickest

Sea Cliffs on Passive Margins

• Sea cliffs found in high latitude regions not associated with plate boundaries

Conclusion

• Complex interplay of geological processes influences coastline morphology and is affected by factors like climate change and tectonics.