Coasts key words Flashcards
(32 cards)
Littoral zone
the wider coastal zone including adjacent land areas and shallow parts of the sea just offshore. split into the - backshore, foreshore, nearshore, offshore.
Cliff profile
the height and angle of a cliff face as well as its features, such as wave-cut notches or changes in slope angle.
Coastal accretion
The deposition of sediment at the coast and seaward growth of the coastline, creating new land. It often involves sediment deposition being stabilised by vegetation.
Dynamic equilibrium
The balanced state of a system when inputs and outputs balance over time. If one element of the system changes because of an outside influence, the internal equilibrium of the system is upset and other components of the system change. By a process of feedback, the system adjusts to the change and the equilibrium is regained.
Holocene
The geological epoch began about 12,000 years ago at the end of the last Pleistocene ice age. Its early stages were marked by large sea level rises of about 35m and a warming interglacial climate.
Dalmatia, Croatia, in the Adriatic Sea was drowned by sea level rise during the Holocene.
Faults
Major fractures in rocks produced by tectonic forces and involving the displacement of rocks on either side of the fault line.
Unconsolidated sediment
Material such as sand, gravel, clay and silt that has not been compacted and cemented to become sedimentary rock (not undergone process of lithification and so is loose and easily eroded)
Pore water pressure
The pressure water experiences at a particular point below the water table due to the weight of water above it.
High pore water pressure causes cliffs to become more unstable.
Fetch
The uninterrupted distance across water over which a wind blows, and therefore the distance waves have to grow in size.
Swash
The flow of water up a beach as a wave breaks
Backwash
When water runs back down the beach to meet the next incoming wave.
Beach morphology
The shape of beach, including its width and slope (the beach profile) and features such as berms, ridges and runnels. It also includes the type of sediment (shingle, sand, mud) found at different locations on the beach.
Blow hole
Forms when a coastal cave turns upwards and breaks through the flat cliff top. Usually, this is because of erosion of especially weak strata or the presence of fault line.
Currents
Flows of seawater in a particular direction driven by winds or differences in water density, salinity or temperature. Some are almost continuous, such as those that form the global thermohaline circulation, and others are more sporadic, such as longshore currents, while some last only for a few hours, such as rip currents.
Mass movement
The downslope movement of rock and soil; it is an umbrella term for a wide range of specific movements including landslide, rockfall and rotational slide.
Isostatic change
A local rise or fall in land level. e.g. isostatic readjustment
Eustatic change
Involves a rise or fall in water level caused by a change in the volume of water. This is a global change, affecting all of the world’s connected seas and oceans.
Accretion
This occurs when sediment is added to a landform, such as a river delta, by deposition. It can build up to form new land, allowing a delta to grow out to sea. It tends to be balanced by subsidence, caused by the weight of newly deposited sediment.
Post-glacial isostatic adjustment
Refers to the uplift experienced by land following the removal of the weight of ice sheets. It is sometimes called post-glacial rebound or post-glacial re-adjustment.
Ria
A drowned river valley in an unglaciated area caused by sea level rises flooding the river valley, making it much wider than would be expected based on the river flowing into it.
Barrier islands
Offshore sediment bars, usually sand dune covered but, unlike spits, they are not attached to the coast. They are found between 500m and 30km offshore and can be tens of kilometres long.
Dredging
Involves scooping or sucking sediment up from the seabed or a river bed, usually for construction sand or gravel, or to deepen a channel so that large boats can navigate it.
Dissipation
The term used to describe how the energy of a wave is deceased by friction with beach material during the wave swash up the beach.
A wide beach slows waves down and saps their energy so, when they break, most energy has gone.
Megaproject
A very expensive (over US$1 billion), technically difficult and usually long-term engineering project. Many megaprojects have multiple aims and often large environmental.
