EROSION, HUMAN IMPACT ON THE LITHOSPHERE EARTH SCIENCE UNIT 11 ◆
Coastal Erosion. Forces That Shape The Earth The Earth is shaped by both internal and external...
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Transcript of Coastal Erosion. Forces That Shape The Earth The Earth is shaped by both internal and external...
Coastal Erosion
Forces That Shape The Earth
• The Earth is shaped by both internal and external processes
• Internally, tectonic processes form the lithosphere
• Externally gradational processes also shape the lithosphere
• These include: rivers, winds, glaciers, and waves
Rivers
• Rivers cut deep valleys and create large deltas
Winds
• Winds carves beautiful rock formations and carry sands
Glaciers• Glaciers flow over continents while slowly
carving out the land and dropping large boulders…
Waves• Waves and currents cut into coastlines and polish sandy
beaches….
The Other Gradational Force…
• Humans are a gradational force• This picture is an example of the effects of over
forestation
• The constant battering of the waves (14,000 waves per day)
• Effects:– erode the shoreline– transport the eroded material– deposit the eroded material elsewhere
Coastal Erosion
Factors Affecting Coastal Erosion
• Softer rocks are more easily eroded• Sea floors that slope gradually have
less erosion because wave break offshore
• Coastlines oriented perpendicular to prevailing winds erode more easily
• Rising sea levels increase erosion rates.
Signs of Coastal Erosion
• Wave-cut notches: An indentation cut into a sea cliff at water level by wave
• Sea caves: cave formed primarily by the wave action of the sea
• Sea arches: form where cliffs are subject to erosion from the sea
• Sea stacks: steep and often vertical column of rock in the sea near a coast, isolated by erosion
Wave Cut Notch
Sea Arches, Caves, Stacks
Sea Arches and Sea Stacks
Elephant Rock, PEI
Hopewell Rocks, NB
Preventing Coastal Erosion
• Riprap – a heap of angular boulders piled along the shoreline
• Breakwater – a wall of boulders built parallel to the shore to take the brunt of the breaking waves
Rip Rap
Breakwater