Coastal morphology
Coastal morphology refers to geomorphology
of the coast. It is often shortened to morphology.
The study of the interaction of waves and currents with the coast. The coast is
shaped by tectonic and structural features, the nature of the rock forming the
coast and depositional and erosive activity. The basic type of coast is
determined by tectonic and structural factors that have been imprinted during
formation of the continents.
Coastal Process: Mainly
there are three coastal processes. They are
1.
Erosion
2.
Transportation, and
3.
Deposition
Coastal Landform:
1.
Erosional landforms
2.
Depositional landforms
Erosional landform: the
landform which is created due to the erosional process is called erosional
landform. There are many types of erosional landforms. They are follows:
a.
Cliff
b.
Notch
c.
Cove
d.
Cave
e.
Stack/chimney rock/Needle/Columns/Pillar/Scalp
f.
Arch
Arch
g.
Inlet
h.
Wave cut platform. Etc.
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. A cliff is a
vertical, near vertical or sloping wall of rock or sediment that borders the
sea. They generally differ in their angle
of slope because of their rock structure and geology, but the processes
involved in their formation are the same. The sea cliff is the most widespread
landform of coastal erosion.
Notch/Wave cut: It forms
after destructive waves hit against the cliff face, causing undercutting
between the high and low water marks, mainly as a result of corrosion and
hydraulic power, creating a wave-cut notch. By the wave processes such as
hydraulic power and abrasion, the waves undercut the face forming a wave-cut
notch. The rock above hangs over the notch.
Cove:
A cove is a small type of bay or coastal inlet. Coves usually have narrow,
restricted entrances, are often circular or oval, and are often situated within
a larger bay. Small, narrow, sheltered bays, inlets, creeks, or recesses in a
coast are often considered coves. Colloquially, the term can be used to
describe a sheltered bay. Coves form where rock runs in bands horizontal to the
direction of wave attack. There is a band of resistant rock closest to the sea
and a band of less resistant rock inland. 
Cave: A cave or cavern is a natural
underground space large enough for a human to enter. Caves form naturally by
the weathering of rock and often extend deep underground. The word
"cave" can also refer to much smaller openings such as sea caves, 
Rock, shelters and grottos. Waves attack
vertical lines of weakness in the rock known as Faults. Processes such as
hydraulic action and abrasion widen these faults into cracks and eventually the
waves will penetrate deeply enough to create caves. Waves are particularly good
at exploiting any weakness in a rock, such as a joint. By the same processes of
erosion, and particularly by hydraulic power and abrasion, any vertical line of
weakness may be increased in size into a cave. However, the rock needs to be
relatively hard or resistant otherwise it will collapse before the cave is
formed. Once a cave has formed, when a wave breaks, it blocks off the face of
the cave and traps the air within it. This compresses the air trapped inside
the cave, which increases the pressure on the roof, back and sides.
Stack: A stack is a geological landform
consisting of a steep and often vertical column or columns of rock in the sea
near a coast, isolated by erosion. Stacks are formed by time, wind, and water,
processes of coastal geomorphology. They are formed when part of a headland is
eroded by hydraulic action, which is the force of the sea or water crashing
against the rock. The force of the water weakens cracks in the headland,
causing them to later collapse, forming free-standing stacks and even a small
island. Without the constant presence of water, stacks also form when a natural
arch collapses under gravity, due to sub-aerial processes like wind erosion.
Stacks can provide important nesting locations for seabirds, and many are popular
for rock climbing.
Stack is a vertical column of rock.
Arch: Once a cave has formed, when a
wave breaks, it blocks off the face of the cave and traps the air within it.
This compresses the air trapped inside the cave, which increases the pressure
on the roof, back and sides. Where the rock has vertical lines of weakness, a
blowhole can be formed extending through the roof of the cave and opening onto
the cliff top. When the tide is high enough water can be forced through natural
part to give a spectacular release of water and the cliff top. If the cave
forms part of a narrow headland, the pressures from the waves may result in the
back of the cave being pushed through to the other side so that it is open at
both sides. The cave then becomes a natural arch. A natural arch or natural
bridge is a natural rock formation where a rock arch forms, with an opening
underneath. Most natural arches form as a narrow bridge.
Inlet: An inlet often leads
to an enclosed body of water, such as a sound, bay, lagoon, or marsh. In sea
coasts, an inlet usually refers to the actual connection between a bay and the
ocean and is often called an "entrance" or a recession in the shore
of a sea, lake, or river. A certain kind of inlet created by glaciation is a
fjord, typically but not always in mountainous coastlines and also in mountain
lakes.
Wave cut platform: A wave-cut platform,
coastal benches, wave-cut benches or shore 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 action of waves. Wave-cut platforms are often
most obvious at low tide when they become visible as huge areas of flat rock.
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. It forms after destructive waves hit against the cliff face,
causing undercutting between the high and low water marks, 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 collapse, 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.
Depositional landform:
Coastal deposition is the laying down of material on the coast by the sea. It
occurs when waves lose energy or when large inputs of sediment are made into
the coastal system - perhaps due to the arrival of fluvial sediment at a river
estuary. Wave refraction in bays also encourages deposition due to the
dispersal of wave energy. Lower-frequency constructive waves often contribute
to deposition due to their strong swash, moving beach material inland. Depositional
coasts are generally found along coast lines of gentle relief, where sediments
from various sources are available. The depositional coasts are found along the
Atlantic and Gulf coasts of the United States. Such coasts are influenced by
the erosional processes and inundation during storms. The following are the
depositional landform.
a.
Sea beach
b.
Bar
c.
Off shore and long shore bar
d.
Spit
e.
Hook
f.
Head land
g.
Loop
h.
Connecting bar
i.
Looped bar
j.
Tombolo
k.
Wing head land
l.
Lagoon.
Sea beach:
A beach is a deposit of loose sediment adjacent to a body of water.
Though sand is common to most beaches, a remarkable diversity of sediment size,
from boulders to fine silt is found on beaches around the world. Larger
particles and steeper slopes are found where wave action is high. Fine
particles and gentle slopes are characteristic of beaches exposed to low wave
action. A beach is a landform along the shoreline 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 the beach are occasionally biological in origin, such as mollusk
shells or coralline algae.
Bar: A bar is a somewhat
linear landform within or extending into a body of water, typically composed of
sand, silt or small pebbles. A bar may separate a lake from the sea, as in the
case of an ayre. They are typically composed of sand, although could be of any
granular matter that the moving water has access to and is capable of shifting
around.
Offshore and long shore bar:
the simplest coastal accumulative relief form, formed by the action of sweeping
breakers. The bar has the form of a low ridge (bar), extending along the
shoreline. Bars can reach hundreds of m or several km in length and 1–4 m in
height; they are defined by the energy of the surf. Such bars are made of sand,
gravel, pebbles, and shells. Ancient offshore bars are relicts of the old
shoreline. A ridge of sand, gravel, or mud built on the seashore by waves and
currents, generally parallel to the shore and submerged by high tides.
Spit: A spit or sand
spit is a deposition landform found off coasts. At one end, spits connect to a head,
and extend into the nose. 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. Spits are created by the
process of Long shore drift. Some eroded material ends up caught up within the
waves and is carried by the sea along the coastline in cells known as littoral
cells. Material is carried along the shore in a zigzag fashion by waves as they
swash material up the beach at an angle and backwash material down the beach at
a right angle. The angle of swash is determined by the prevailing wind (the
dominant or main direction in which the wind blows).
Hook: Hook is created mainly
by the ocean current due to giving pressure from one side to a spit. Hook is
created from the spit due to giving pressure. Once a spit forms, wave action
remains strong on the seaward side of the spit, and the longshore drift
continues to transport sediment to the end of the spit, where it is deposited.
The spit protects the bay from ocean waves, creating a shadow zone of calm
water on its landward side. Deposition in the shadow zone at the end of the
spit can cause the spit to turn landward and form a hook.
Head land: A headland is a
point of land, usually high and often with a sheer drop that extends out into a
body of water. The word is often used as a synonym for promontory; a headland
of considerable size often being called a cape. A headland is often referred to as simply a
head, either in context or in names such as Beachy Head.
Tombolo: Away from the
mouths of rivers, deposition also occurs wherever wave activity is weak. For
example, a small island close to shore shelters the mainland shoreline from
strong ocean waves, thus diminishing wave activity between the island and the
mainland. This region is called a wave shadow zone. The longshore drift cannot
pass through this quiet region because wave motion is needed to maintain
longshore drift. Therefore, any sediment carried by longshore drift into such
an area is deposited there. The deposition of sediment eventually builds up a
sand bridge that connects the island to the mainland. The sand bridge is called
a tombolo. Wave energy also dissipates in the lee of large sea stacks or
islets. Wave refraction sweeps sediment behind the obstruction from two
directions, depositing it as a slender finger called a tombolo.
Lagoon: Spits can extend
across the mouth of a bay, but wave action is usually strong enough to wash
sand out to sea or be deposited in the embayment. They may curve into the bay
or stretch across connecting to the other side as a bay mouth bar. When the bay
is closed off by a bar it becomes a lagoon.
Connecting bars:
Sometimes a spit is built across any stretch of water and joins
Is-lands, headlands, islands and headlands. Such a spit is called a connecting
bar.
Loops:
Under special conditions opposing
currents may encounter littoral currents in such a way that it leads to the
landward growth of hooks until they connect with the coastline forming loops. 
