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Coastal Landscapes and change (Lithology (Sedimentary (Examples-…
Coastal Landscapes and change
Sediment characteristics
Sediment-
Is solid material that is moved and deposited in a new location.
Can consist of rocks and minerals, remains of plants/animals and can be as small as a grain of sand and as large as a boulder
Rarely moves seaward and inward due to waves, usually transported by along coastlines by currents
Transport processes
Traction
Sediment
rolls along
by waves and currents, examples: pebbles,cobbles and boulders
Saltation
The sediment
bounces along
, either because of the force of water or of wind. Examples: Sand-sized particles
Suspension
Sediment is
carried
in the water column- Slit and Clay particles
Solution
Dissolved material is carried in the water as
solution
- Chemical compounds in Solution
Offshore Bars
Is a
long narrow bridge of deposited materials
, sand can be found lying away from parallel to the coast
Example - Hordle cliff , Hampshire
Formation
: as waves approach a gently sloping coast, friction between the waves and the sea bed causes the waves to break at some distance from the coast. Over time, more materials are built up parallel to the coast to form a ridge of sand called 'offshore bar'
Body of water may be cut off from the open sea by the offshore bar, this body of water is called a
lagoon
Geology + landforms
Geological structure is the arrangement of rocks in three dimensions
There are three elements to geological structure
Strata
- the different layers of rock exposed in a cliff
Deformation
- tilting and folding by tectonic activity
Faulting
- major fractures that have moved rocks from their original position
Geological structure performs two types of rock
Concordant
(Pacific coasts)- When rock strata runs parallel to the coastline such as Dorset
Discordant
(Atlantic coasts)- When different rock strata intersect the coast at an angle, rock type varies along coastline
Dominated by headlands and bays
Lithology
Definition - refers to different rock types
Igneous rock
Examples
-
Granite, Basalt, Dolerite
Igneous rocks are
crystalline
, the interlocking crystals make for strong, hard erosion resistant rock
Erosion rate-
Very slow,
less than 0.1cm per year
Metamorphic
Examples-
Slate, Schist and Marble
Crystalline metamorphic rocks are resistant to erosion
Erosion rate-
Slow
0.1cm-0.3cm per year
Sedimentary
Examples
-
Sandstone, limestone and shale
Most are clastic, erodes faster than igneous and metamporhic
Shale has many bedding places and fractures- makes it more vulnerable to erosion
Erosion rate-
Moderate to fast
0.5 cm -10 cm per year