This is represent about the coastal land form which are created from erosion and deposition. as well as it includes about coral land forms.

1. D.G. Nishavi Kaushalya Ranasinghe
B.A. (Hons) Geography
Department of Geography and Environmental Management
Sabaragamuwa University of Sri Lanka

3. Coast Ocean
 A coastline or a seashore is the
area where land meets the sea or
ocean.
 An ocean , the sea of classical
antiquity is a body of saline water
that composes much of a planet’s
hydrosphere. On Earth, an ocean
is one of the major conventional
divisions of the World Ocean,
which occupies two-thirds of the
planet's surface. These are, in
descending order by area, the
Pacific, Atlantic, Indian, Southern,
and Arctic Oceans.

4. How Creating
Coastal And
Oceanic
Landforms
Erosion Transport Deposition
Abrasion
Solution
Corrasion
Material which
are bring by
waves are
called wave
transportation.
There are more
mud and sand.
Material which
are bring by
waves are
deposit near the
beach is called
deposition.

5.  Erosional and depositional landforms of coastal and oceanic areas are the
result of the action of ocean waves. We can classified these landforms
under ,
Erosional coastal and oceanic landforms
Depositional coastal and oceanic landforms
Volcanism landforms
Biogeological landforms

6.  Cape
 Bay
 Cliff
 Wave-cut platform
 Sea cave
 Sea arches
 Sea stacks
 Island
 Blowhole
 Headland
 Inlet
 Submarine canyon
 Peninsula
 Oceanic basin
 Beach
 Spit
 Baymouth Bar
 Beach cusps
 Barrier island
 Archipelago
 Cuspate foreland
 Tombolo
 Oceanic plateau
 Abyssal fan
 Lagoon

9. Erosional Landforms

10. Cape
 A cape is a headland or promontory of large size extending into a body of
water, usually the sea.
 A cape usually represents a marked change in trend of the coastline.
 Their proximity to the coastline makes them prone to natural forms of
erosion, mainly tidal actions.
 This results in capes having a relatively short geologic lifespan.
 Capes can be formed by glaciers, volcanoes, and changes in sea level.
Erosion plays a large role in each of these methods of formation.
Eg: Cape Comorin, Cape Horn
Cape Cornwall

11. Bay
 A bay is a large body of water connected to an ocean or sea, formed by an
inlet of water due to the surrounding land blocking some waves and often
reducing winds.
 Bays also exist in in-land environments as an inlet to any larger body of
water, such as a lake or pond, or the estuary of a river.
 Currents can make waves more constant, and soft rocks speed erosion.
Hard rock eroded less quickly, leaving headlands.
 There are various ways that bays can be created.
• Continental drift
• Glacial and river erosion.
• Folding of the earth's crust
Eg: Bay of Bengal, Hudson bay

12. Cliff
 A cliff is a vertical, or near vertical, rock exposure.
 Cliffs are formed as erosion landforms due to the processes of erosion and
weathering that produce them.
 Cliffs are common on coasts, in mountainous areas, escarpments and along
rivers.
 Cliffs are usually formed by rock that is resistant to erosion and weathering.
 Sedimentary rocks most likely to form cliffs include sandstone, limestone,
chalk, and dolomite. Igneous rocks such as granite and basalt also often form
cliffs.
Eg: Judas peak, Cape Town ,
Cape Point, Western Cape

13. Sea cave
 A sea cave, 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. The driving force in littoral cave
development is wave action.
 Erosion is ongoing anywhere that waves batter rocky coasts, but where sea cliffs
contain zones of weakness, rock is removed at a greater rate along these zones.
 As the sea reaches into the fissures thus formed, they begin to widen and deepen
due to the tremendous force exerted within a confined space, not only by direct
action of the surf and any rock particles that it bears, but also by compression of
air within.
Eg: Matainaka Cave (1.5
km in length), on the South
Island

14. Some sea
caves in world

15. Blowhole
 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.
 Blowhole is also the name of a rare geologic feature in which air is blown
through a small hole at the surface due to pressure differences between a
closed underground system and the surface.
Eg: Hummanaya in Sri Lanka

16. Wave-cut platform
 A wave-cut platform is the narrow flat area often found at the base of a sea cliff
or along the shoreline of a lake, bay, or sea that was created by the erosion of
waves.
 Wave-cut platforms are often most obvious at low tide when they become visible
as huge areas of flat rock.
 Mainly as a result of corrosion and hydraulic power, creating a wave-cut notch.
 This notch then enlarges into a cave.
 The waves undermine this portion until the roof of the cave cannot hold due to
the pressure and freeze-thaw weathering acting on it, and collapses, resulting in
the cliff retreating landward.
 The base of the cave forms the wave-cut platform as attrition causes the
collapsed material to be broken down into smaller pieces, while some cliff
material may be washed into the sea. This may be deposited at the end of the
platform, forming an off-shore terrace.

17. Step of formation of
wave cut platform
Eg:Shore platform at Southerndown, South Wales
Raised beach and shore platform, Bleik,
Norway

18. Sea arches
 Natural arches commonly form where cliffs are subject to erosion from the sea,
rivers or weathering (subaerial processes); the processes "find" weaknesses in
rocks and work on them, making them larger until they break through.
 Wave refraction concentrates the wave energy on the headland, and an arch
forms when caves break through the headland. When these eventually collapse,
they form stacks and stumps.
 On concordant coastlines rock types run parallel to the coastline, with weak
rock (such as shale) protected by stronger rock (such as limestone) the wave
action breaks through the strong rock and then erodes the weak rock very
quickly.
 Eg: Durdle Door in south England
The Arch of Cabo San Lucas
in Mexico

19. Sea stacks
 A sea stack is a geological landform consisting of a steep and often vertical
column or columns of rock in the sea near a coast, formed by erosion.
 Stacks typically form in horizontally-bedded sedimentary or volcanic
rocks, particularly on limestone cliffs.
 The formation process usually begins when the sea attacks small cracks in a
headland and opens them.
 The cracks then gradually get larger and turn into a small cave.
 When the cave wears through the headland, an arch forms. Further erosion
causes the arch to collapse, leaving the pillar of hard rock standing away
from the coast - the stack. Eventually, erosion will cause the stack to
collapse, leaving a stump. This stump usually forms a small rock island
 Eg: Po Pin Chau in Hong Kong
Tri Brata and Sail Rock, Russia

21. Peninsula
 A peninsula is a piece of land that is bordered by water on three sides but
connected to mainland. The surrounding water is usually understood to
belong to a single, contiguous body, but is not always explicitly defined as
such. A peninsula can also be a headland (head), cape, island promontory,
bill, point, or spit.
 Eg: Cape Peninsula, South Africa
Cape York Peninsula, Queensland
South India (Peninsular India)

23. Beach
 A beach is a landform along the coast of an ocean, sea, lake, or
river.
 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.
 Beaches are the result of wave action by which waves or
currents move sand or other loose sediments of which the beach
is made as these particles are held in suspension.
 Alternatively, sand may be moved by saltation.Beach materials
come from erosion of rocks offshore, as well as from headland
erosion and slumping producing deposits of scree.
• Eg: Copacabana beach, Rio de Janeiro
Kirinda Beach, in Sri Lanka

24. Spit
 A spit is a deposition landform found off coasts.
 A spit is a type of bar or beach that develops where a re-
entrant occurs, such as at cove's headlands, by the process of
longshore drift.
 Longshore drift (also called littoral drift) occurs due to waves
meeting the beach at an oblique angle, and backwashing
perpendicular to the shore, moving sediment down the beach
in a zigzag pattern. Longshore drifting is complemented by
longshore currents, which transport sediment through the
water alongside the beach.
 These currents are set in motion by the same oblique angle of
entering waves that causes littoral drift and transport sediment
in a similar process.
• Eg: Dungeness Spit

26. Lagoon
 A lagoon is a shallow body of water separated from a larger body of water
by barrier islands or reefs.
 Lagoons are commonly divided into coastal lagoons and atoll lagoons.
 Coastal lagoons form along gently sloping coasts where barrier islands or
reefs can develop off-shore, and the sea-level is rising relative to the land
along the shore.
 Coastal lagoons are usually connected to the open ocean by inlets between
barrier islands. The number and size of the inlets, precipitation,
evaporation, and inflow of fresh water all affect the nature of the lagoon.
 Eg: Glenrock Lagoon in Australia
Lagoa dos Patos lagoon in Brazil
Baticalo in Sri Lanka

27. Barrier island
 Barrier Islands, a coastal landform and a type of Decan system, are
exceptionally flat and lumpy areas of sand, that are parallel to the mainland
coast.
 They usually occur in chains, consisting of anything from a few island 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.
 An ample sediment supply is also a requirement for barrier island
formation.
 Eg: The Mississippi-Alabama barrier islands guarding Mobile Bay
and Mississippi Sound.

29. Tombolo
 A tombolo is a deposition landform in which an island is attached to the mainland
by a narrow piece of land such as a spit or bar.
 Several islands tied together by bars which rise above the water level are called a
tombolo cluster.True tombolos are formed by wave refraction.
 As waves near an island, they are slowed by the shallow water surrounding it.
 These waves then refract or bend around the island to the opposite side as they
approach.
 Eventually, when enough sediment has built up, the beach shoreline, known as a
spit, will connect with an island and form a tombolo.
 Eg: Chesil Beach, seen from the Isle of Portland

30. How creating A Tombolo
Creating a Tombolo
Land
Ocean

31. Cuspate foreland
 Cuspate forelands are geographical features found on coastlines and
lakeshores that are created primarily by longshore drift.
 Formed by accretion and progradation of sand and shingle, they extend
outwards from the shoreline in a triangular shape.
 Some cuspate forelands may be stabilised by vegetation, while others may
migrate down the shoreline. the most widely accepted process of formation
of Cuspate forelands is involves long shore drift.
Ex:Dungeness along the southern coast of Britain

32. Baymouth Bar
 A baymouth bar is a depositional feature as a result of longshore drift. It is
a spit that completely closes access to a bay, thus sealing it off from the
main body of water.
 These bars usually consist of accumulated gravel and sand carried by the
current of longshore drift and deposited at a less turbulent part of the
current. Thus, they most commonly occur across artificial bay and river
entrances due to the loss of kinetic energy in the current after wave
refraction.

33. Oceanic Landforms

34. Oceanic basin
 In hydrology, an oceanic basin may be anywhere on Earth that is covered
by seawater, but geologically ocean basins are large geologic basins that are
below sea level.
 Geologically, there are other undersea geomorphological features such as
the continental shelves, the deep ocean trenches, and the undersea
mountain ranges (for example, the mid-Atlantic ridge) which are not
considered to be part of the ocean basins; while hydrologically, oceanic
basins include the flanking continental shelves and shallow, epeiric seas.

35. Abyssal fan
 Abyssal fans are underwater geological structures associated with large-
scale sediment deposition and formed by turbidity currents.
 Turbidity currents start when something, for example an earthquake,
triggers sediments to be pushed over the edge of the continental shelf and
down the continental slope, creating a submarine landslide.
 The slowing current has a reduced ability to transport sediments and
deposition of the coarser grains begins, creating a submarine fan.
 The current continues to slow down as it moves towards the continental
rise until it reaches the level bottom of the ocean.
 Eg: Bengal Fan

36. Mid-ocean ridge
 A mid-ocean ridge is an underwater mountain system that consists of
various mountain ranges (chains), typically having a valley known as a rift
running along its spine, formed by plate tectonics.
 This type of oceanic ridge is characteristic of what is known as an oceanic
spreading center, which is responsible for seafloor spreading. The
production of new seafloor results from mantle upwelling in response to
plate spreading
 A mid-ocean ridge demarcates the boundary between two tectonic plates,
and consequently is termed a divergent plate boundary.
 Ex: Andes, the longest continental mountain range
 Atlantic mid oceanic range

37. OCEANIC TRENCH
 The oceanic trenches are hemispheric-scale long but narrow topographic
depressions of the sea floor.
 They are also the deepest parts of the ocean floor. Oceanic trenches are a
distinctive morphological feature of convergent plate boundaries.
 Trenches are generally parallel to a volcanic island arc, and about 200 km
(120 mi) from a volcanic arc.
 Oceanic trenches typically extend 3 to 4 km (1.9 to 2.5 mi) below the level
of the surrounding oceanic floor.
Eg:The greatest ocean depth to be sounded is in the Challenger Deep
of the Mariana Trench, at a depth of 11,033 m (36,198 ft)
below sea level.
 There are about 50,000 km (31,000 mi) of convergent plate margins,
mostly around the Pacific Ocean—the reason for the reference “Pacific-
type” margin—but they are also in the eastern Indian Ocean, with relatively
short convergent margin segments in the Atlantic Ocean and in the
Mediterranean Sea.

38. The Peru-Chile Trench
Mariana Trench

40.  Coral reefs are diverse underwater ecosystems held together by calcium
carbonate structures secreted by corals.
 Coral reefs are built by colonies of tiny animals found in marine waters
that contain few nutrients.
 Most coral reefs are built from stony corals, which in turn consist of polyps
that cluster in groups.
 Most of the coral reefs we can see today were formed after the last glacial
period when melting ice caused the sea level to rise and flood the
continental shelves.
 This means that most modern coral reefs are less than 10,000 years old.
 As communities established themselves on the shelves, the reefs grew
upwards, pacing rising sea levels. Reefs that rose too slowly could become
drowned reefs.
 They are covered by so much water that there was insufficient light.
 Coral reefs are found in the deep sea away from continental shelves, around
oceanic islands and as atolls.
 The vast majority of these islands are volcanic in origin. The few
exceptions have tectonic origins where plate movements have lifted the
deep ocean floor on the surface.

41. The three principal reef types are:
 Fringing reef – directly attached to a shore, or borders it with an
intervening shallow channel or lagoon
 Barrier reef – reef separated from a mainland or island shore by a deep
channel or lagoon
 Atoll reef – more or less circular or continuous barrier reef extends all the
way around a lagoon without a central island.
Island with fringing reef
off Yap, Micronesia
A small atoll in the Maldives