1
Q
Mechanical weathering
A
weathering caused by forces
2
Q
Freeze - Thaw weathering
A
Rain water freezes in the cracks of rocks and expands
3
Q
Chemical weathering
A
weathering caused by chemical alteration to the rocks and minerals due to exposure
4
Q
Acid rain
A
Minerals in the rock can react with the acid rain causing the rock to dissolve
5
Q
Formation of Levees
A
- When a flood occurs friction with the land reduces velocity and causes deposition.
- Heavy sediment is deposited closer to the river and the size gets smaller with increased distance.
- With each flood the banks gar built up higher
6
Q
Formation of Floodplains
A
- A flood occurs.
- Water spills onto the floodplain. Friction causes the water to lose energy which causes sediment to be deposited.
- Over time the floodplain grows in size with the sediment from previous floods
7
Q
Formation of Spits
A
- Spits are formed when the coastline changes direction.
- Long shore drift continues in the direction of the prevailing wind and deposits sediment out at sea.
- As sediment builds up it forms a spit.
- The end of a spit can curve allowing a salt march to develop behind it.
8
Q
Formation of Bars
A
- Bars are formed when long shore drift continues to deposit sediment in the direction of the prevailing wind causing a spit to extend across a bay
- Bars can sometimes create lagoons - lakes trapped behind the ridge of sand
9
Q
The Formation of Sand dunes
A
- Dunes form when sand blown from the beach is deposited around an obstacle
- These embryo dunes grow overtime and become stabilised by vegetation
- In time, rotting vegetation adds organic matter making it more fertile
- Between dunes a dune slack may form. A dune is a depression in which ponds may form
- The mature dunes are so fertile that woodlands begin to grow
10
Q
The Formation of Interlocking Spurs
A
- In the uplands the geology is made of hard rock
- Due to freeze - thaw weathering the valley gradually broadens
- Repeated weathering causes rock to break and fall into the river where they are carried away
- The water takes a winding path which goes around the hard rock
- This results in the formation of alternate sides, these are interlocking spurs
11
Q
The Formation of a Waterfall
A
- A river flows over hard and soft rock
- Due to differential erosion the soft rock erodes faster undercutting the hard rock
- This creates a plunge pool which grows in size due to abrasion and hydraulic action
- Gravity and lack of support causes the overhang to collapse
- The materials from the overhang are used in abrasion to cause further erosion and undercutting
- This process repeats and overtime the waterfall retreats, leaving a steep sided gorge
12
Q
Types of Mass movement
A
Slumping, Sliding and Rockfall
13
Q
Slumping
A
- The soil gets saturated and then slumps down a slope
- The material is often unconsolidated
- Occurs on weaker rocks like clay
- Slow process, can take days or weeks
14
Q
Sliding
A
- Large blocks of consolidated rock ,like limestone, slide down hill
- One-way landslides can happen if waves hit the base of the cliff
- This makes the bottom of the cliff weaker, undercutting the top
- The removal of support allows blocks of rock to slide down the cliff
15
Q
Rockfall
A
- This is when smaller bits of rock fall off the cliff face
- This often occurs on slopes that are very steep
- The rock is loosened by physical processes like freeze-thaw weathering
- Rockfall is very rapid, it only takes a few seconds
Geography
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