geological action of waves and currents, and the features that is morphological features forming as a result of its action is explained

1. WELCOME
Presented by
Haritha A
Govt college kottayam

2. GEOLOGICAL ACTION OF
WAVES AND CURRENTS
COASTAL UPWELLING AND
COASTAL DOWNWELLING

3. WAVES
• Generated by the wind blowing over the surface of ocean and sea water.
• Friction of wind moving over the water surface cause the water particle to move
along circular or near circular orbits in a vertical plane parallel to the direction of
wind.
• The ocean waves are oscillatory waves as they causes an oscillatory wave motion.

4. • CREST
• TROUGH
• WAVE PERIOD
• WAVE LENGTH
• WAVE HEIGHT
• ZONE OF SURF
• SWASH
• BACKSWASH

5. CURRENT
•In the current the actual movement of the water over great distance ,
which may be caused by various factors such as, the difference in
temperature , salinity, action of steady and periodic wind.

6. •MARINE EROSION
•MARINE TRANSPORTATION
•MARINE DEPOSITION
GEOLOGICAL ACTIONS OF WAVES AND
CURENTS

7. MARINE EROSION
• HYDRAULIC ACTION
• ABRASSION
• ATTRITION
• CORROSION

9. FEATURES FORMED
• Blowholes
• Sea caves
•Sea arches
•Sea stack
• Sea stump
• Wave cut cliff
• Wave cut benches
• Wave cut notches

11. BLOW HOLES
A blowhole is formed as sea caves grow
landwards and upwards into vertical shafts
and expose themselves towards the surface,
which can result in blasts of water from the
top of the blowhole.
 Blowholes are likely to occur in areas
where there are crevices, such as lava
tubes, in rock along the coast.
 These areas are often located
along fault lines and on islands.
 As powerful waves hit the coast, water
rushes into these crevices and bursts out
in a high pressured release

12. WAVECUT PLATFORMS
• A wave-cut platform also called wave-
cut benches
• It is the narrow flat area found at the base
of a sea cliff.
• This was formed by wave erosion as the
waves undercut a cliff.
Sometimes the landward side of the
platform is covered by sand, forming
the beach, and then the platform can
only be identified at low tides or
when storms move the sand.

13. SEA CAVES
• Also known as a littoral cave, is a type
of cave formed primarily by
the wave action of the sea.
• The primary process involved is erosion
• In order to form a sea cave, the host rock
must first contain a weak zone.
• In metamorphic or igneous rock, this is
typically either a fault and in sedimentary
rocks, this may be a bedding-plane
parting or a contact between layers of
different hardness

14. SEA ARCHES
•A sea arch is a natural opening eroded out
of a cliff face by marine processes.
•Destructive waves erode along the line of
weakness
•e.g. fault line or joint
• Repeated hydraulic action and abrasion
widen and deepen the line of weakness.
•The supporting roof of the arch is known
as the keystone

15. SEA STACK
• Sea stack is consisting of a steep and
often vertical column or columns of
rock in the sea near a coast, formed
by wave erosion.
• They are formed when part of
a headland is eroded by hydraulic
action
• Without the constant presence of
water, stacks also form when a natural
arch collapses under gravity, due
to sub-aerial processes like wind
erosion

16. SEA STUMP

17. WAVECUT CLIFF
• Also called an abrasion
coast.
• In coastal areas, the land
surface dips at a relatively steep
angle
The continuous action of
marine waves on the coastline,
create a steep declivity known
as a cliff

18. WAVECUT NOTCHES
The process of cliff erosion.
The sea attacks the base of the
cliff forming a wave-cut notch.
The notch increases in size
causing the cliff to collapse.

19. MARINE TRANSPORTATION
•Transportation is the movement of material in the sea and along the coast by
waves.
•The movement of material along the coast is called longshore drift.

20. •Longshore drift happens when waves moves towards the
coast at an angle.
•The swash (waves moving up the beach) carries material up
and along the beach.
•The backwash carries material back down the beach at right
angles. This is the result of gravity. This process slowly
moves material along the beach.
•Longshore drift provides a link between erosion and
deposition. Material in one place is eroded, transported then
deposited elsewhere.

21. Longshore drift is the main process of transportation the
material moves in four different ways. These are:
Traction - large material is rolled along the sea floor.
Saltation - beach material is bounced along the sea
floor.
Suspension - beach material is suspended and carried by
the waves.
Solution - material is dissolved and carried by the water.

23. MARINE DEPOSITION
Deposition is when eroded material is dropped by constructive
waves.
It happens because wave have less energy.
Deposition creates a range of landforms
•Littoral deposits
•Neritic deposit
•Bathyal deposit
•Abyssal deposit

24. • BARRIER ISLANDS
• SPIT
• BEACHES
• BARS
• TOMBOLO
• ISTHMUS
Features formed:

26. BARRIER ISLANDS
• Barrier islands are long, narrow, offshore deposits of sand or sediment that
run parallel to the coastline.
• They are separated from the main land by a shallow sound, bay, or lagoon

27. • They usually occur in chains, consisting of anything
from a few islands to more than a dozen
• The length and width of barriers and overall
morphology of barrier coasts are related to parameters
including tidal range, wave energy, sediment supply, sea-
level trends, and basement controls

28. SAND SPIT
• A sandpit ,a deposition bar or beach landform found off coasts or lake shores.
• It develops in places where re-entrance occurs, such as at a cove's headlands, by
the process of longshore drift by longshore currents.

29. • The drift occurs due to waves meeting the beach at an
oblique angle, moving sediment down the beach in a
zigzag pattern.
• This is complemented by long shore currents, which
further transport sediment through the water alongside
the beach.
• These currents are caused by the same waves that
cause the drift

30. A beach is a landform along a body of water.
It usually consists of loose particles, which are often composed
of rock, such as sand, gravel, shingle, pebbles, or cobblestones.
The particles comprising a beach are occasionally biological in origin,
such as mollusc shells or coralline algae.
• Sand Beaches
• Rock Beaches
• Lava Beaches
BEACHES

32.  A shoal is a natural submerged ridge, bank, or bar that consists of,
or is covered by, sand or other unconsolidated material, and rises
from the bed of a body of water to near the surface.
 Shoals are also known as sandbanks, sandbars, or gravel bars.
 Two or more shoals that are either separated by shared troughs or
interconnected by past and or present sedimentary and
hydrographic processes are referred to as a shoal complex
SHOAL

34. TOMBOLO
• A deposition landform in which an island is attached
to the mainland by a narrow piece of land such as
a spit or bar.
• Once attached, the island is then known as a tied
island.
• Several islands tied together by bars which rise above
the water level are called a tombolo cluster.
• Two or more tombolos may form an enclosure (called
a lagoon) that can eventually fill with sediment.

36. UPWELLING
Upwelling is an oceanographic phenomenon that involves wind-
driven motion of dense, cooler, and usually nutrient-rich water
towards the ocean surface, replacing the warmer, usually nutrient-
depleted surface water.
The three main drivers that work together to cause upwelling
are wind, Coriolis effects, and Ekman transport
Coastal upwelling is the best known type of upwelling, and the
most closely related to human activities as it supports some of the
most productive fisheries in the world.

38. COASTAL UPWELLING
 Wind-driven currents are diverted to the right of the winds in the Northern
Hemisphere and to the left in the Southern Hemisphere due to the Coriolis
effect.
 The result is a net movement of surface water at right angles to the direction of
the wind, known as the Ekman transport
 When Ekman transport is occurring away from the coast, surface waters moving
away are replaced by deeper, colder, and denser water.
 Normally, this upwelling process occurs at a rate of about 5–10 meters per day,
but the rate and proximity of upwelling to the coast can be changed due to the
strength and distance of the wind
 Upwelling occurs in the open ocean and along coastlines.

40.  Downwelling is the process of accumulation and sinking of
higher density material beneath lower density material, such as
cold or saline water beneath warmer or fresher water or cold air
beneath warm air.
 It is the sinking limb of a convection cell.
 Upwelling is the opposite process and together these two forces
are responsible in the oceans for the thermohaline circulation.
 The sinking of cold lithosphere at subduction zones is another
example of downwelling in plate tectonics.
DOWNWELLING

41. COASTAL DOWNWELLING
 Downwelling occurs at anti-cyclonic places within the ocean where
warm rings are spinning clockwise creating surface convergence.
 When these surface waters converge, they push the surface water
downwards.
 Another way that downwelling can occur is by the wind driving the
sea towards the coastline.
 Regions that have downwelling have low productivity because the
nutrients in the water column are utilized but are not continuously
resupplied by the cold, nutrient-rich water from below the surface.

43. Thank you