Transcript Coasts and Shorelines Notes What is a coast?

Coasts and
Shorelines Notes
What is a coast?
A
coast is the edge of land that is met by
the water’s edge, it “fronts” the open
ocean
1. Coasts are temporary
structures, often
subject to rapid change.
2. The location of a coast
depends on tectonic
activity and the level of
water in the ocean.
3. The shape of a coast is
a product of many
processes.
4. Coasts are classified as primary or secondary.
5. Human interference in coastal processes rarely
increases the long-term stability of a coast.
Movement of Water
•
It is the force that creates the features.
•
Waves and currents erode the shoreline to
create different features.
Longshore Currents
•
•
an ocean current
that moves parallel
to shore, but only
within the surf
zone
formed as waves
break and release
energy at an angle
to the shoreline
that flows parallel
to the coast
Longshore Currents
•
are significant because they can
transport great quantities of
sediment from where it is introduced
into the ocean by a stream to beaches
up or down the coast
PRIMARY COASTS

Young coasts dominated by terrestrial
influences.

Essentially the same coast as sea level
stabilized after the last ice age.
Ex. Martha’s
Vineyard and
Nantucket
What are some types of
primary coasts?
 Land
erosion coasts
 Coasts built out by land processes
 Volcanic coasts
 Coasts shaped by earth movements
SECONDARY COASTS
 Older
coasts that have been changed by
marine influence
What are some processes that
shape secondary coasts?
 Waves
and currents
 Stream erosion
 Abrasion of wind-driven particles
 Freeze/thaw cycles
 Slumping
SECONDARY COAST
SECONDARY COAST
BEACHES
A
beach is a zone of loose particles that
covers a shore.
What are the features of a beach?

Berm- mounds of earth material

Berm Crest- highest spot on a berm

Backshore
 Foreshore
What are the features of a beach?

Beach Scarp - a nearly vertical slope along
the beach caused by waves

Longshore Trough - a long, wide, shallow
depression of the sea floor parallel to the
shore.
 Longshore Bars - ridge of sand, gravel, or
mud built on the seashore by waves and
currents, generally parallel to the shore
and submerged by high tides. Also known
as an offshore bar.
COASTS FORMED BY BIOLOGICAL
ACTIVITY
Fringing Reefs - clings to the margin of land.
Barrier Reefs - separated from land by a
lagoon.
Atolls - ring-shaped islands of coral reef
enclosing lagoons.