Landforms Flashcards
what river landforms are caused by erosion?
-waterfalls and gorges
-interlocking spurs
where are waterfalls and gorges found?
in the upper course
how are waterfalls and gorges formed?
•softer rock is eroded by hydraulic action and abrasion more than the layer of harder rock over it
•the water erodes the softer rock further undercutting the hard rock and creating a waterfall
•over time the hard rock becomes unsupported and collapses due to erosion. The collapsed rock swirls around the foot of the water fall eroding softer rock by abrasion creating a plunge pool
•Overtime, the waterfall retreats leaving behind a gorge
What are interlocking spurs?
A series of ridges projecting out on alternate sides of a valley and around which a river winds its course.
how are interlocking spurs formed?
•vertical erosion occurs in the upper course creating a v shaped valley
•the river isn’t powerful enough to erode laterally so it winds around hills made of resistant rock
•this creates an interlocking spur
where are interlocking spurs found?
in the upper course of a river where rocks are hard
what are rapids?
fast flowing sections of river where the gradient is quite steep and water is turbulent
how are rapids formed?
they are formed from ridges of harder rock amongst soft rock
where are rapids found?
the upper course
What river landforms are caused by deposition and erosion?
meanders and oxbow lakes
where are meanders and oxbow lakes found?
the middle course
how are meanders formed?
•fast flowing water in the outside bends wear the river away and overtime undercuts the bank
•the river deposits its load of mud and shingle on the inside bend where the river flows slowly
•the outside bend continues to cut into the bank resulting in the river bending more
What does the cross section of a meander look like?
how are oxbow lakes formed?
•the fast flow of water on the outside bend results in erosion
•the outside bends move closer together and the meander neck becomes more narrow
•when there is a high discharge the river cuts across the neck and takes a straight course leaving an oxbow lake
What landforms are caused by deposition?
-floodplains
-levees
-estuaries
what are levees?
raised embankments at the side of the river channel that occur when a river is prone to flooding
how are levees formed?
•when a river bursts at it’s banks friction with land reduces energy causing deposition of heavy sediment close to the river. The sediment becomes progressively smaller further from he channel
•after every flood the banks are built up higher on the side of the river forming levees
where are levees found?
lower course
what are floodplains?
a large area of flat land either side of a river that is prone to flooding
where are floodplains found?
middle and lower course
how are floodplains formed?
•they are formed meanders migrate across due to lateral erosion
•when they reach the edge of the floodplain they erode the valley side creating a buff
what are estuaries?
a tidal part if the river where fresh water migrates with salt water from sea
how are estuaries formed?
•they are formed as the tide reached its highest point where water moves slow and sediment is deposited
•overtime more and more builds up creating large areas of mudflats snd muddy banks are exposed
where are estuaries found?
at the mouth of the river on the lower course
What landfrorms can be found along the river tees
-High Force is a waterfall found in Forest-in-Teesdale
-There are meanders in Darlington where the lower course of the river is
