lesson 1- coasts and natural systems Flashcards
explain the concept of sediment cells (4)
-a sediment cell is a largely self contained stretch of coastline
-regarded as closed systems as sediment is not usually transferred from one to another
-but in reality, a little does
each sediment cell usually has many smaller sub cells
-they have defined boundaries such as headlands
-storms, floods etc can disrupt the cell
OR
-a sediment cell is a section of coast that has been controlled for management purposes, where geogolgy is contained and regulated to keep a healthy sediment budget
-usually shaped by the topography of local cliffs and barriers, which prevent escape/travel of sediment to other cells
-sediment is usually deposited by constructive waves, tides or through hum interception such as groynes.
-inside are sub cells systems with little to no movement of sediment, closed system but not always true due to wind changing
-as sediment is primarily transported by longshore drift, a change in wind can have a significant influence
what is the quarternary glacial period
a series of glacial events separated by interglacial events from millions of years ago to now
what is dynamic equilibrium
a state of balance between continuing processes
how is a coast a open system
has inputs from an external system (sediment carried down rivers), and outputs to other natural systems (eroded rock transported into the ocean)
-wind generates waves (energy)
what is backshore
area between the high water mark and the landward limit
-changes only occur during a storm
what is foreshore
area between high water mark and low water mark
-important for marine processes
what is inshore
area between the low water mark and the point which waves dont influence the land below them
what is offshore
area where waves dont influence land under them and which activity is limited to deposition
what is nearshore
area from the high water mark to where the waves begin to break
explain the concept of isostatic uplift (4)
-local changes caused by subsidence or uplift of the crust related either to changes in the amount of ice on the land
-or to growth or erosion of mountains
-at the end of the last ice age, vast areas in the North saw their ice sheet retreat and melt
-areas such as the North American Great Lakes filled with water and are slowly becoming shallower
explain the concept of tectonic uplift (4)
-coastlines in areas where there has been net sea level rise in the recent past often have estuaries and fjords
-this valley was filled with ice during the last glaciation, and there has been a net rise in sea levels here since then
-coastlines in areas where there has been net sea level drop in the recent past have wave cut platforms
-uplifted beach lines are another product of these,though these are difficult to see through vegetation
explain the concept of eustatic uplift (4)
-eustatic sea level change refers to changes in the global sea level, rather than changes in the elevation of land relative to sea level
-can be caused by changes in the volume of water in the oceans, changes in the shape and size of ocean basins, and changes in the gravitational field
-a main driver is climate change, which can cause melting of ice sheets and glaciers, thermal expansion of sea water, and changes in ocean circulation patterns
-can have significant impacts on coastal ecosystems and communities, including increased flooding and erosion, loss of habitats and saltwater intrusion into freshwater resources
