2. Spit
• A Spit is a long, narrow
accumulation of sand or
shingle, one end attached to
the land the other projecting
out to sea or across a river
estuary. Many spits have
hooked or curved ends. They
are formed where longshore
drift moves large quantities of
sand & shingle along the coast
& where the coastline
suddenly changes direction to
leave a shallow sheltered area
of water. In the diagram X to
Y represents the original
coastline.
Da Nong, Vietnam
3. Spit
• As the fetch & prevailing winds
are from the south west, in this
diagram, longshore drift will be
moved eastward along the
coastline. At headland X the
coastline changes direction &
shingle will be deposited in
water sheltered by the headland
(B). Further deposition of sand
enables the feature to build up to
sea level (C) & extends its
length (D). The spits growth is
limited by river currents
scouring its end & transporting
sediment out to sea.Spurn point.
4. Spit (Salt Marsh)
• Behind the spit a quiet
tranquil lagoon forms &
sediment (brought in both by
sea currents & from rivers) is
deposited there. Eventually
the sediment builds up to sea
level & a Salt marsh forms.
5. Hooked (Recurved) Spit
• Occasionally storms
come in from the south
east or east & move
sediment in a different
direction forming the
curve or hook (E).When
the wind returns to
normal the spit resumes
its growth eastward (F).
Sand is blown on land
(G), forming sand dunes.
• Hurst Castle Spit, Hants.
8. Double Spit
• Formed from a breach
of a pre existing spit
or bar.
• Usually by a river or
storm.
• Christchurch Harbour,
Dorset
• Laudhelm Beach,
Maine.
9. Barrier Beach (Bar)
• The spits growth is limited
by river currents scouring
its end & transporting
sediment out to sea. If there
is no river the spit may
grow across the estuary and
form a Bar.
• Slapton Sands, Devon
10. Barrier Island
• These are formed by rising sea level.
As the sea rose at the end of the last ice
age large quantities of sediment (beach)
were pushed upward in front of the
rising sea level (bulldozerisation),
forming a ridge or island.
• The barriers move inland by
“overwash” as sediment is eroded off
the seaward side of the barrier &
redeposited on the landward side.
• North Carolina, USA.
12. Wave Refraction
• As waves approach the
coastline, they come in
contact with the sea bed &
slow down, this happens
first off the headlands.
• The wave is still in deep
water off the bays.
• The wave is therefore bent.
• The energy is concentrated
on the headlands (erosion)
• Energy is dissipated in the
bays (deposition)
Click Here
13. Tombolo
• The waves are refracted
around the island & set up 2
opposing LSD directions.
• These merge behind the
island & sand is deposited
linking the mainland & the
island
• Goat Island, California
• San Antonia, Costa Rica
