Transcript Nov 2_Coastal Erosion PPT

Coastal Erosion:
Waves, Beaches and Coasts
Erosion
• A great many steep, rocky coasts have
been visibly changed by wave erosion
• Soluble rocks such as limestone dissolve
as waves wash against them.
• More durable rocks such as granite are
fractured by the enormous pressures
caused by waves slamming into them.
• Wave impact pressures have been measured as
high as 60 metric tons per square meter
• Some portions of coasts can retreat 10 to 30
meters in a single storm
• Soluble rocks such as limestone dissolve as
waves wash against them.
• More durable rocks such as granite are fractured
by the enormous pressures caused by waves
slamming into them.
• Headlands: points of land
• Can be straightened by wave action.
• Rocky cliffs form from wave erosion of
headlands.
• The eroded material is deposited in quieter
waters of nearby bays.
Headlands
Signs of Coastal Erosion:
• sea cliffs (steep slopes that retreat inland),
produced by the erosion of headlands
• wave-cut platforms (horizontal bench of
rock formed beneath the surf zone), the
platform widens as the sea cliff retreats
Wave Cut Platform
Costal Erosion
• http://www.horton.ednet.ns.ca/staff/webb/g
eology/8Weathering%20to%20Soils/coast
alerosion.ppt
• A picture of a cliff as it is slowly eroded
over time.
• stacks (erosional remnants of headlands
• arches (bridges of rock left above
openings eroded in headlands or stacks)
• barrier islands (ridges of sand that parallel
the shoreline and extend above sea level)
ie: Atlantic City, Miami Beach
Caves, Arches, Stacks
Arches, Stacks
Prevention
• Seawalls can be constructed along the
base of retreating cliffs to prevent wave
erosion. Seawalls are designed to absorb
wave energy.
• Breakwaters
• Vegetation (Sumatra EQ: loss of corals
and mangroves)
Global Warming?
Global Warming?
Florida….smart?