Coastal landforms are shaped by the interaction of waves, currents, and tides. Waves cause erosion through abrasion, hydraulic action, and solution. This forms cliffs, notches, wave-cut platforms, sea caves, stacks, blowholes, and geos. Depositional landforms include beaches made of sand and other sediments between the low and high tide lines. Offshore, bars, barriers, spits, hooks, loops, tombolos, and lagoons form through sediment deposition.

1. COASTAL LANDFRMS
BY
Dr. Pramod Kumar Anthwal

2. WAVE, CURRENT AND TIDES
• Coastal landforms are those who are formed by oceanic waves.
• Marine landforms are produced by the joint action of wave, current and tides.
• Wave: The oscillation of surface water with little or no transfer of water molecule.
• Current: current are continued and progressive forward movement of water in a
fairly defined action.
• Tides are periodic rise and fall of water by the pull, exerted on the earth by the
moon and sun.

3. Types of marine erosion
• Abrasion:
• Hydraulic action:
• Solution :

5. Cliffs
• Steep rocky coast rising almost vertically above sea water is called sea
cliff.
• The lower part of sea cliff is eroded by wave action and the upper
part resembles like a hanging wall.
• Notch indicates the point of wave attack by high tide. It keeps on
increasing.

7. Wave cut platform
• Wave cut platform is formed due to the process of cliff recession. As
notch formation goes up the upper roof of cliff collapse and thus a
formation of new cliff starts. The residual debris is removed by wave
action and thus a platform starts shaping. This platform which is cut
by waves is called wave cut platform.

10. Sea cave
• The headland protruding into the sea becomes the center of wave
attack.
• If a joint extends across the headland, wave action can hollow out a
cave, known as sea cave.

12. Stack
• Eventually because of the enlargement of cave, its arch (roof of cave) collapses
and thus the seaward part of the cave stands detached from the coast.
• Such isolated remnant of headland projection wall above sea level is called stack.
Also known as chimney rock, needles, columns, pillars etc.

13. Stack

14. Blowhole and Geo
• When the line of weakness (joints) lies on the cave roof or roof of cliff, the
hydraulic action of wave compressed air leads to the falling in of joints block,
leading finally to the development of hole in the roof. This is known as blow
holes.
• When the roof finally falls and the fallen debris removed, long narrow inlets are
developed called a geo.

16. Depositional
landforms

17. Beaches
• Shore: is a narrow strip of land between the low tide watermark and highest point
reached by storm wave and high tides.
• Beaches sandy area between high water mark and low water mark. It consists of
unconsolidated sediments like sand, cobbles, pebbles, boulder, fine silt etc. Sand is
most common material. Beach is regularly modified by waves.
• Coast: is generally defined as the land bordering the shore.
• Shoreline: is a line of contact between land and water.

18. Beaches, shore, shore-line, coast

19. Cusp Beaches
• The crescent shaped narrow ridges extending seaward, deposited by sea wave, is
called cusp beach. The horns are made up of coarser material and the embayment
contains finer sediment.

20. Sand Bar and barriers
• The ridges, embankments or mounds of sands formed by sedimentation through
sea waves parallel to the shoreline, inside the sea are called bars.
• The extensive form of bar is called barriers. They don’t inundate at the time of
high tide.
• Offshore Bars : Larger formation than barrier is called offshore bars. This could be
hundreds of km long. Cape Hatteras of US is the longest offshore bar of the world.

22. Spit, Hook and Loop
• Spit: If the one end of bar is attached with coast and other is projected into the sea
is called spits.
• Hook: If the spit resembles like the hooks it is called hooked spits or hook.
• Loop: If the arm of hook is also attached to main land, it is called loop.

25. Connecting bars, Tombolo and Lagoons
• Connecting Bars: When a bar connects two landmasses are called
connecting bars.
• While a bar become Tombolo when it connect the main land with an
island.
• Lagoons: Lagoon forms when a cove or bay is completely enclosed by
bars. Ex Chilika lake.
• Isthmus: the difference between tombolo and isthmus is isthmus is
formed my tectonic activity while tombolo is a sand bar formed by
the deposition of sand. Example:-admass bridge connecting India to
shrilanka.

26. Thanks