Marine Science Coastal Erosion Notes

1. Coastal Erosion

2. Weathering vs. Erosion
• Weathering: Chemical or mechanical breaking down of
rock (but stays where it is)
• Erosion: The movement or transport or broken down
rock

3. Coastal Dynamics
• Processes that create and shape coastlines along the
ocean

4. Agents of Coastal Dynamics
• Coasts constantly change and in most areas moves inland
• Processes:
 Wind
 Waves
 Currents
 Tides
 Sea Level Change
 Erosion

5. Effects of Coastal Erosion
• Long term shaping of coasts
• Temporary redistribution of sediment

6. Longshore Current Erosion
• Energy from waves
dissipates down the
shoreline taking sediment
with it

7. Wave Action
1. Hydraulic Action –
incoming waves
compress air in cracks
in rock faces
2. Attrition – loose rocks
grind rock face and
break down
3. Corrosion – pH of ocean
dissolves rock materials
such as limestone

8. Effects due to Coastal Rock Density
• Harder rock areas weather
slower
• Softer areas (soil, etc.) erode
faster leaving unique
formations
• Over time these formations
even out by the erosion of
harder rock structures filling
in holes with sediment

9. Primary Factors Affecting Erosion
• Coastal make up (type of rock, density, etc.)
• Size of rock debris vs. wave energy
• Size of beach to dissipate energy
• Off shore structures (ex. sandbars)
• Seafloor configuration
• Rising sea levels

10. Secondary and Tertiary Factors
• Vegetation
• Slope
• Human Activity
• Coastal Management

11. Coastal Structures:
• Barrier Islands: large sediment
deposits the form between
ocean and the shoreline; always
changing (ex: OBX)

12. Coastal Structures:
• Dunes: Accumulated sand with stabilizing vegetation;
dissipate storm energy from reaching main coastline

13. Deltas
• Sediment formations where enough sediment from a river
can be deposited and not be carried away by ocean energy
due to wide continental shelves
Predicted due to sea level rise, flood
management, etc.

14. Coral Reefs
• Biologically/natural made areas in shallow waters that help
dissipate energy coming into shore

15. Human Built Coastline Structures
• Groins – perpendicular protrusions
protect from longshore current
erosion
• Jetties – similar to groins but
protect harbor entrances
• Breakwaters – run parallel to shores
to create artificial harbors
• Seawalls – block waves from
reaching and eroding shores