Formations Flashcards
Formation of a stack?
Caine, Can, Actually, Stack, Simon
Crack, Cave, Arch, Stack, Stump
Formation of interlocking spurs?
Interlocking spurs ‘fingers’ of land that stick out in a valley. The river is near its source, and is not powerful enough to cut through the ‘spurs’ of land, so has to flow around them.
Formation of a meander?
- A meander is a bend in a river
- A river rarely flows in a straight line - it will bend around something in its course.
- This results in areas of slower and faster water flow. The river flows faster on the outside and erodes the outside bends of the river channel by the processes of hydraulic action and abrasion - this forms a river cliff. - — The river flows more slowly on the inside bend of a river channel and deposits some of its load - this forms a river beach.
- Continuous erosion on the outer bank and deposition on the inner bank forms a meander in the river.
OX BOW LAKE
the neck of the meander becomes narrower due to erosion on the outside of the 2 meander bends. The neck will continue to get closer and closer. The neck of the meander gets cut through and so the water flows through this. (An ox bow lake is left because the process of deposition has sealed the end of the old meander completely.)
Headland and Bay formation?
- bands of less resistant soft rock (clay, sands) & more resistant hard rock e.g. chalk and limestone
- bays have formed due to rapid erosion
- Headlands are left sticking out as hardrock has resisted erosion
- Whebn formed the bays become sheltered by the headlands and so less eroded
- Once formed the headland is then left more vunerable to erosion and the waves energy is concerntrated here
Beach formation?
- A beach is a deposit of sand and shingle at the coast
- Sandy ebaches are mainly found in sheltered bays
- Constructive waves form beaches as they have a strong swash and weak backwash to build up the beach
- Not all beaches are made of sand bc these high-energy environments wash away teh finer sand and leave behind the larger pebbles
- Tese come from nearby eroded cliffs and are deposited on the vast accumulations out to sea
- A berm is a clear ridge of sand and one of these marks the high tide line
Formation of a spit?
- Sediment is carried by longshore drift.
- When there is a change in the shape of the coastline, deposition occurs. A long thin ridge of material is deposited. This is the spit.
- A hooked end can form if there is a change in wind direction.
- Waves cannot get past a spit, therefore the water behind a spit is very sheltered. Silts are deposited here to form salt marshes or mud flats.
Formation of sand dunes?
- Microclimate and soil conditions chaneg alliowing colonisation by additional species
- Marram leaves further reduce wind speed and capture more blown sand. Decaying plants add humus
- Marram grass colonies embryo dunes stabilixing futrther dune migration
- Wind speed drops behind accumulation resulting in more sand deposition
- Sand axxumulated against a feature and builds upepr ebach height
Floodpain formation?
A floodplain is an area of land which is covered in water when a river bursts its banks.
- Floodplains form due to both erosion and deposition.
- Erosion removes any interlocking spurs, creating a wide, flat area on either side of the river
- During a flood, material being carried by the river is deposited (as the river loses its speed and energy to transport material).
- Over time, the height of the floodplain increases as material is deposited on either side of the river.
The floodplain is often a wide, flat area caused by meanders shifting along the valley.
Estuyary formation?
- Sea levels rise, low lying valley sides either side of rivers were flooded creating esteuaries
- Where fresh water and salt water meet and during a rising tide the RIEVRS VELOCITY FALLS and sediment is deposited
- This forms extensive mudflats in sheltered areas (exposed at low tide)
- Overtime these may develop into saltmarshes
Levee formation?
Levees occur in the lower course of a river when there is an increase in the volume of water flowing downstream and flooding occurs.
- Sediment that has been eroded further upstream is transported downstream.
- When the river floods, the sediment spreads out across the floodplain.
- When a flood occurs, the river loses energy. The largest material is deposited first on the sides of the river banks and smaller material further away.
- After many floods, the sediment builds up to increase the height of the river banks, meaning that the channel can carry more water (a greater discharge) and flooding is less likely to occur in the future.