Beach Deposits (Handout)
Beach Deposits (Handout)
Beach Deposits (Handout)
What is BEACH?
A beach is a landform alongside a body of water which consists of loose particles. The
particles composing a beach are typically made from rock, such
as sand, gravel, shingle, pebbles, or cobblestones. The particles can also be biological
in origin, such as mollusc shells or coralline algae.
Sand is a naturally occurring granular material composed of finely
divided rock and mineral particles. It is defined by size, being finer
than gravel and coarser than silt. Sand can also refer to a textural class of
soil or soil type; i.e., a soil containing more than 85 percent sand-sized
particles by mass.
Gravel is a loose aggregation of rock fragments. Gravel is classified
by particle size range and includes size classes from granule- to boulder-
sized fragments. In the Udden-Wentworth scale gravel is categorized into
granular gravel (2 to 4 mm or 0.079 to 0.157 in) and pebble gravel (4 to
64 mm or 0.2 to 2.5 in).
Shingle is a small, round stones that cover a beach or the ground by
the edge of a river. Example is a shingle beach (also referred to
as rocky beach or pebble beach) is a beach which
is armoured with pebbles or small- to medium-sized cobbles (as opposed
to fine sand). Typically, the stone composition may grade from
characteristic sizes ranging from 2 to 200 millimetres (0.1 to 7.9 in)
diameter.
Pebbles is a clast of rock with a particle size of 2 to 64 millimetres based
on the Krumbein phi scale of sedimentology. Pebbles are generally
considered larger than granules (2 to 4 millimetres diameter) and smaller
than cobbles (64 to 256 millimetres diameter). A rock made predominantly
of pebbles is termed a conglomerate.
Cobblestones is a natural building material based on cobble-sized
stones, and is used for pavement roads, streets, and buildings. In
England, it was commonplace since ancient times for flat stones with a flat
narrow edge to be set on edge to provide an even paved surface. This
was known as a 'pitched' surface and was common all over Britain, as it
did not require rounded pebbles.
Mollusc (or mollusk) shell is typically a calcareous exoskeleton which
encloses, supports and protects the soft parts of an animal in
the phylum Mollusca, which includes snails, clams, tusk shells, and
several other classes.
Coralline algae are red algae in the order Corallinales. They are
characterized by a thallus that is hard because of calcareous deposits
contained within the cell walls. The colors of these algae are most typically
pink, or some other shade of red, but some species can be purple, yellow,
blue, white, or gray-green.
changes seasonally.
BEACH EROSION occurs when waves and currents remove sand from the beach
system.
- is often defined as the loss or displacement of land along
the coastline due to the action of waves, currents, tides. wind-driven water, waterborne
ice, or other impacts of storms.
Features of Erosional shores:
Headland a narrow piece of land that projects from a coastline into the sea.
Wave-cut cliff 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 erosion.
Sea cave also known as a littoral cave, is a type of cave formed primarily by
the wave action of the sea.
Sea arch is a natural opening eroded out of a cliff face by marine processes.
Sea stack a column of rock standing in the sea, remaining after erosion of cliffs.
Marine terrace a terrace formed along a seashore by the merging of wave -
cut and wave-built terraces.
1) WAVES are formed by winds blowing over the sea. Waves are the most
important force on sandy coasts because they transport sand on- and offshore
and can also move sand along the shore.
2) WINDS picks up sand grains deposited by waves and moves them landwards
until vegetation (or other obstructions) slows the wind, and the sand grains fall.
3) CURRENTS are created by winds, waves, tides and river flows. These currents
may transport large amounts of sand and alter the shape of offshore sandbars.
4) TIDES play a more indirect role in transporting sand and altering the shape of
sandy coastal areas. The ebb and flow of tidal waters can create tidal currents
that transport sand and are mostly seen in areas where there is a narrow
passage between landforms.
5) STORMS can dramatically change beach, dune and bar systems in a very short
period. Storms produce high energy and steep waves that can erode beaches,
destroy foredunes and even erode the dunes behind.
Spit
Bay barrier
A narrow shoal or small point of land projecting from the shore across the mouth
of a bay and severing the bay's connection with the main body of water.
Tombolo
From the Italian tombolo, derived from the Latin tumulus, meaning 'mound', and
sometimes translated as ayre, 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.
Barrier island
A long broad sandy island lying parallel to a shore that is built up by the action of
waves, currents, and winds and that protects the shore from the effects of the
ocean.
Features:
1. Ocean beach
2. Dunes
3. Barrier flat
4. High salt marsh
5. Low salt marsh
6. Lagoon
Delta
Is an area of low, flat land shaped like a triangle, where a river splits
and spreads out into several branches before entering the sea.
BEACH RESTORATION also known as beach nourishment is an expensive and
time-consuming process, but it has also become essential now that so many
communities depend on beaches not just for recreation but also for protection from the
ravages of ocean-bound storms.
Example: