Coasts Flashcards
Wave height
Distance between the wave trough and crest
Wave crest
Highest point of a wave
Wave period
Time taken for the wave motion from trough to trough OR crest to crest (usually 1-20 seconds)
Wave amplitude
Distance between the still water depth level and wave crest
Wave base
An are of no movement which occurs at a depth of half the wavelength
Wave trough
The lower point in a wave
Wavelength
Distance between two successive crests
Wave orbit
The circular motion that water particles make
Still water depth
Is measured from the sea bed
Wave frequency
No of wave per minute
Wave steepness
Ratio of the wave hight to wavelength (wav height divided by wavelength)
No higher than 1:7 as this is when a wave breaks
Swash
Mass of foaming water that translates energy up the beach when a wave had broken
Backwash
Return of water down the beach as a result if gravitation pull
Fetch
The distance over which the wind can blow
The distance a wave travels
What effects wave energy?
Wind velocity (speed)
Duration (time which wind blew)
Fetch (distance over which wind blew)
Wave
Created by the action of wind on the surface of the sea
Coast
Transitional zone between the land and the sea
This zone is not fixed and is often described as dynamic as it is subject to change
What are the two types of wave
Waves debrief from local wings (sea)
Waves created by distance storms (swell) which may travel thousands of miles
How are waves formed
Created by the frictional drag of the wind
Define mass movement
Movement of rock fragments and soil under the influence of gravity
What is the slowest form of mass movement
Soil creep
Less than 1cm per year
Almost continuous process
What are the 3 main causes of soil creep
Raindrop impact
Wet-dry periods
Freeze-thaw
Name all types of mass movement
Soil creep Solifluction Earth flows Mud flows Slides and slumps Rockfall
Succession
Gradual change in plant species/communities over time
Primary succession
Succession is allowed to occur unhindered and progress from bare soil right through to climatic climax vegetation
Secondary succession
succession is interrupted
Can either by natural or human induced
Climatic climax vegatation
The end of the succession succession
Vegetation is in equilibrium with climate of an area
Sub climax succession
Occurs when a natural event (flood) prevents climatic climax vegetation being reached
Plagio climax vegetation
Occurs when humans interrupt the succession sequence
Pioneer species
First plants to colonise an area. Characteristics include high growth rate, small size, wide dispersal and fast population growth
Climax communities
End of the succession sequence.
Characterised by slower growth rates, larger size, lower rates if dispersal, lower rates of colonisation, longer lives
What happens as you move inland sand dunes
Exposed sand decreases
Rise in humus content,more vegetation
Reduced salt in water - more freshwater
PH moves from alkaline to acid due to less saltwater and increase in humus
Increase in species diversity as conditions become less harsh
Salt marsh
Intertidal and depositional landform
Area of low lying land that is frequently flooded with saltwater
Occur in sheltered river estuaries or behind spits
Sea level change
Eustatic: amount of water in sea changes - global
Isostatic: when land rises or falls and creates a relative change in base level - local/smaller scale
Emergent landforms
Raised beaches - former wave cut beaches now raised above current sea levels
Coastal plains/ marine platforms - large flat areas which are formed sea beds/floors exposed above sea levels
Submergence landforms
Rias - drowned river valleys
Damnation coasts - flooded river valleys that run parallel to the coast
Fjords - flooded glacial u valleys
Fjards - flooded glacial lowlands ( V shaped)
Estuaries - flooded valleys of large, broad rivers - mouth of a river
Features associated with beaches
Depositional
Cusps - crescent shaped features that form in beaches where there is a junction of sand and shingle
Berms - ridge coarse sand and shingle on upper beach deposited by spring tides and storm waves
Storm beach - noticeable semi permanent ridge bound at level of highest spring tides
Ridges and runnels - features at low water characterised by a series if raised areas and depressions that run parallel to shoreline
