Paper 1 Landforms Flashcards
(11 cards)
Describe how waterfalls and gorges are formed?
Waterfalls are formed when a layer of hard rock is above a layer of soft rock. Hydraulic action and abrasion cause the soft rock to recede and an overhang form due to undercutting. The overhang eventually falls down and undercutting happens again forming a new overhang, cycle continues resulting in a large gorge left downstream
Describe how an meander is formed?
Meanders are formed in the river due to erosion and deposition. Due to the rivers thalweg, the banks are eroded through hydraulic action and abrasion. On the inside bend the river flow is slow so deposition occurs and on the outside bend the river flow is fast so erosion occurs. This processes exaggerate the river meander
Describe how an oxbow lake is formed?
An oxbow lake is formed from meanders in the rivers due to erosion and deposition. The neck of the meander becomes quite thin and narrow. When the river floods, it breaks through and over time takes the straighter course. Deposition seals of the meander leaving and oxbow lake and when it dries up an oxbow lake scar
Describe how a levee is formed?
During a flood, the river overflows its banks and deposits sediment. The heaviest material is deposited closer and the lighter material is deposited further away. Over many floods these deposits build up which raise the river banks and form levees
Describe how a meander migrates?
The thalweg is located on the outer bend of the river where the river has the most energy. Therefore there is erosion on the outer banks while there is deposition on the inner banks and over time this causes a meander to migrate and move and change shape.
Describe how a flood plain builds up?
During periods of flooding the river overflows its bands and spreads out across the land losing energy, decreased energy causes the river to deposit material such as alluvium and repeat flooding and deposition build up a flood plain beside the river.
Describe how headlands and bays
Erosion occurs along coastlines where hard and soft rock lie next to each other, the soft rock is eroded quicker than the hard rock by marine processes such as hydraulic action and abrasion which leaves a bay and the hard rock is eroded slower leaving a headland.
The bay becomes a sheltered area where waves lose energy and deposition occurs forming beaches. Headlands remain exposed to wave attack which leads to further erosion
Describe how stumps, stacks, arches, caves and blowholes are formed?
Cracks form in the headland due to hydraulic action, weathering and abrasion. The cracks are widened by weathering and erosion forming caves. Continued erosion deepens the cave so it breaks through the headland forming an arch, the roof is attacked by weathering and collapses due to gravity leaving a stack and the stack is eroded at its base leaving a stump
Describe how a spit is formed?
Longshore drift transport sediment along the coastline in the direction of the prevailing wind, when there is a coastline change, material is deposited as wave speed decreases, over time sediment deposited builds up and becomes a spit. The tip of the spit may change directions due to a secondary wind and calmer waters behind a spit encourage the development of salt marshes and mudflats
Describe how a sand dune develops?
Sand is transported to the back of the beach via wind
when the wind meets an obstacle depositions occurs
as more stand builds up embryo dunes form, these grow and become fore dunes and then yellow dunes as they gain vegetations and then grey dunes and they progress further inland
Describe how V Shaped Valleys and Interlocked Spurs are formed?
River uses most of energy to overcome friction, rest is to erode vertically
this creates steep v shaped valleys
sides are attacked by freeze thaw
valley gets weakened and sides collapse
leaves v shape
interlocked spurs form as river encounters more resistant rock
takes paths of least resistance
forms layers of V called spurs
