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