FIGURE 13.16 Nearly 300 barrier islands rim
the Gulf and Atlantic coasts. The islands
along the coast of North Carolina are
excellent examples. (Photo by Michael Collier)
VIRGINIA
NORTH CAROLINA
Cape Lookout
Hatteras
Island
Hatteras
Island
Road
Dunes
Albemarle
Sound
P a m li c o S o u n d
ATLANTIC OCEAN
ATLANTIC OCEAN
NC
Pamlico Sound
319
Stabilizing the Shore
melted, sea level rose and flooded the area
behind the beach-dune complex.
The Evolving Shore
A shoreline continually undergoes modification regardless of its initial configuration.
At first most coastlines are irregular,
although the degree of, and reason for, the
irregularity may differ considerably from
place to place. Along a coastline of varied
geology, the pounding surf may initially
increase its irregularity because the waves
will erode the weaker rocks more easily
than the stronger ones. However, if a shoreline remains stable, marine erosion and
deposition will eventually produce a
straighter, more regular coast.
FIGURE 13.17 illustrates the evolution of an initially irregular coast. As
waves erode the headlands, creating
cliffs and a wave-cut platform, sediment
is carried along the shore. Some material is deposited in the bays, whereas
other debris is formed into spits and
baymouth bars. At the same time, rivers
fill the bays with sediment. Ultimately, a
generally straight, smooth coast results.
C O N C E P T C H E C K 1 3 . 6
Describe the formation of each labeled
feature in parts B and C of Figure 13.17.
List three ways that barrier islands may
form.
Stabilizing the Shore
Shorelines
Waves and Beaches
Today the coastal zone teems with human
activity. Unfortunately, people often treat
the shoreline as if it were a stable platform
on which structures can be built safely. This
approach jeopardizes both people and the
shoreline because many coastal landforms
are relatively fragile, short-lived features
that are easily damaged by development.
As anyone who has endured a tsunami or a
tropical storm knows, the shoreline is not
always a safe place to live. We will examine
this latter idea more closely in the section
on “Hurricanes—The Ultimate Coastal
Hazard.”
Compared with natural hazards such as
earthquakes, volcanic eruptions, and landslides, shoreline erosion appears to be a
more continuous and predictable process
that causes relatively modest damage to
limited areas. In reality, the shoreline is a
dynamic place that can change rapidly in
response to natural forces. Exceptional
storms are capable of eroding beaches and
cliffs at rates that far exceed the long-term
GEODe
ESSENTIALS
OF GEOLOGY
2
1
the Gulf and Atlantic coasts. The islands
along the coast of North Carolina are
excellent examples. (Photo by Michael Collier)
VIRGINIA
NORTH CAROLINA
Cape Lookout
Hatteras
Island
Hatteras
Island
Road
Dunes
Albemarle
Sound
P a m li c o S o u n d
ATLANTIC OCEAN
ATLANTIC OCEAN
NC
Pamlico Sound
319
Stabilizing the Shore
melted, sea level rose and flooded the area
behind the beach-dune complex.
The Evolving Shore
A shoreline continually undergoes modification regardless of its initial configuration.
At first most coastlines are irregular,
although the degree of, and reason for, the
irregularity may differ considerably from
place to place. Along a coastline of varied
geology, the pounding surf may initially
increase its irregularity because the waves
will erode the weaker rocks more easily
than the stronger ones. However, if a shoreline remains stable, marine erosion and
deposition will eventually produce a
straighter, more regular coast.
FIGURE 13.17 illustrates the evolution of an initially irregular coast. As
waves erode the headlands, creating
cliffs and a wave-cut platform, sediment
is carried along the shore. Some material is deposited in the bays, whereas
other debris is formed into spits and
baymouth bars. At the same time, rivers
fill the bays with sediment. Ultimately, a
generally straight, smooth coast results.
C O N C E P T C H E C K 1 3 . 6
Describe the formation of each labeled
feature in parts B and C of Figure 13.17.
List three ways that barrier islands may
form.
Stabilizing the Shore
Shorelines
Waves and Beaches
Today the coastal zone teems with human
activity. Unfortunately, people often treat
the shoreline as if it were a stable platform
on which structures can be built safely. This
approach jeopardizes both people and the
shoreline because many coastal landforms
are relatively fragile, short-lived features
that are easily damaged by development.
As anyone who has endured a tsunami or a
tropical storm knows, the shoreline is not
always a safe place to live. We will examine
this latter idea more closely in the section
on “Hurricanes—The Ultimate Coastal
Hazard.”
Compared with natural hazards such as
earthquakes, volcanic eruptions, and landslides, shoreline erosion appears to be a
more continuous and predictable process
that causes relatively modest damage to
limited areas. In reality, the shoreline is a
dynamic place that can change rapidly in
response to natural forces. Exceptional
storms are capable of eroding beaches and
cliffs at rates that far exceed the long-term
GEODe
ESSENTIALS
OF GEOLOGY
2
1