Erosional landforms - P

Question 1

What are erosional landforms

Answer 1

Landforms created by erosional processes

Question 2

Define bay

Answer 2

a recessed, coastal body of water which is partially surrounded by land

Question 3

Define headland

Answer 3

an area of usually more - resistant rock which extends into the sea, surrounded by water on 3 sides

Question 4

define cliff

Answer 4

a steep, often m vertical or overhanging, face of rock

Question 5

define shore platform

Answer 5

a flat or gently sloping rock surface found at the base of cliffs

Question 6

Define geo

Answer 6

a narrow steep-sided inlet

Question 7

Define blowhole

Answer 7

a vertical shaft between a cliff top and a cave, where spray from waves may burst out of during storm conditions

Question 8

define cave

Answer 8

a natural opening in a cliff face, large enough for humans to explore

Question 9

define arch

Answer 9

a wave - eroded passage through a small headland

Question 10

define stack

Answer 10

a steep and often vertical column of rock in the sea

Question 11

Define stump

Answer 11

a short, eroded remnant of a sea stack that juts above the sea surface

Question 12

How to bays and headlines usually form

Answer 12

Adjacent to each other - usually due to the bands of rocks

Question 13

What is a disconcordant coastline

Answer 13

when the rocks are perpendicular to the coastline so the weaker rocks are eroded to form bays while more resistant rocks remain as headlands

Question 14

What is a concordant coastline

Answer 14

when rocks lie parallel to the coastline, more resistant rocks could protect softer rocks inland - usually a straight coastline.

Question 15

What is the width and depth of bays determined by

Answer 15

• width of band of weaker rocks
• differential rates of erosion

Question 16

What is wave refraction

Answer 16

is more significant where bays and headlands form

Question 17

What is an orthogonals

Answer 17

imaginary lines, perpendicular to wave fronts, representing the transfer of energy as a wave moves towards the coast

Question 18

Explain wave refraction

Answer 18

• waves refract around the headland causing orthogonal to converge and wave energy too be focused on the headland
• in bays the orthogonal diverge and the energy is dissipated leading to deposition

Question 19

Can bays and headlands be formed on concordant coasts

Answer 19

Yes but usually they are small - e.g. Lulworth Cove, Dorset - the limestone has been eroded through the softer clays to form a cove

Question 20

Why do cliff profiles vary

Answer 20

They depend on the geology

Question 21

Which two types of cliffs have a near vertical profile

Answer 21

• horizontally bedded strata
• landward dipping strata

Question 22

Which type of cliffs has the profile following the angle of the strata

Answer 22

• seaward dipping strata

Question 23

What causes the horizontally bedded strata to be near vertical

Answer 23

Undercutting leads to rockfall and rocks retreating inland parallel to the coast

Question 24

What causes the landward dipping strata to be near vertical

Answer 24

rocks are loosened by weathering and are difficult to dislodge so the profile is gradually lowered by weathering and mass movement

Question 25

What causes the seaward dipping strata to follow the angle of the dipping strata

Answer 25

Undercutting removes the basal support - rock layers loosened by weathering slide into the sea along the bedding plane

Question 26

Explain how a shore platform is formed

Answer 26

- destructive waves cause undercutting between low and high tides, forming a wave cut notch - continued undercutting weakens support off rock above so it collapses - regular removal of debris means cliff retreats and is steep - as the process continues the cliff becomes higher - at the base a gently sloping shore platform is formed

Question 27

When is a shore platform exposed

Answer 27

during Low tide

Question 28

What process eroded shore platforms the most

Answer 28

abrasion as there is a lot of rock debris thats dragged across the surface by wave action

Question 29

What stops the undercutting of a cliff (shore platform)

Answer 29

- as they become wider, friction slows approaching waves causing them to break before reaching the cliff - this slows down and eventually stops undercutting

Question 30

How wide does the shore platform have to be to stop undercutting of the shore platform

Answer 30

usually 500m away from the cliff

Question 31

What types of weathering are key process in the formation of a shore platform

Answer 31

- solution, freeze thaw and salt crystallisation take place depending on rock type and climate - algae can accelerate weathering when exposed at low tide - algae makes water more acidic by releasing CO2 (chemical weathering)

Question 32

How do shore platforms usually slope

Answer 32

slope seawards between 0 and 3 degrees

Question 33

When is erosion concentrated in one location

Answer 33

during low and high tide

Question 34

What is formed due to concentrated erosion at the low water mark (LWM) and high water mark (HWM)

Answer 34

- a ramp at the HWM - A small cliff at the low water mark

Question 35

When do cliffs and ramps form better

Answer 35

when the tidal range is less than 4m

Question 36

Why is a higher tidal range that 4m worse at forming ramps and cliffs

Answer 36

the erosion is spread over a larger area of the platform

Question 37

What are goes

Answer 37

narrow, steep sided inlets - occur even on coasts with resistant geology as there can be lines of weakness

Question 38

Explain how geos form

Answer 38

- weak points are eroded more rapidly by wave action that the more resistant rock around them - this continues until a steep sided inlet is formed

Question 39

What is a key process in the formation of a geo

Answer 39

hydraulic action - as forcing air and water into the joins will weaken the rock strata

Question 40

What is an example of a geo

Answer 40

Huntsman’s Leap - Wales is 35m deep in Limestone

Question 41

How is a blowhole formed

Answer 41

when part of a tunnel-like cave collapses along a master joint, it may form a vertical shaft that reaches the cliff top

Question 42

what happens to a blowhole ion storm conditions

Answer 42

water may spray out of it in plumes of white aerated water

Question 43

What is unique about the size of blowholes

Answer 43

they are usually quite small but large in diameter

Question 44

What is an example of a blowhole

Answer 44

Trevone, Cornwall - 25m deep and 25m wide

Question 45

Where do a caves, arches, stacks and stumps tend to form

Answer 45

- develop around headlands - and represent the erosional stages

Question 46

Explain how a cave is formed

Answer 46

- due to wave refraction, energy is concentrated on the sides of headlands - points of weakness, such as faults or joints are then exploited by erosional processes - a small cave may develop one one side or even both

Question 47

Where do caves usually form

Answer 47

between high and low tide levels as wave attack is more concentrated here

Question 48

Explain how an arch is formed

Answer 48

if a cave enlarges to an extent that it extends through to the other side of the headland (possibly meeting another cave) an arch is formed

Question 49

Explain how a stack is formed

Answer 49

continued erosion widens the arch and weakens its support, weathering processes may cause the arch to collapse, leaving a stack isolated form the headland

Question 50

Explain how a stump is formed

Answer 50

further erosion at the base of the stack may eventually cause further collapse, leaving a small, flat portion of the original stack as a stump (may be only visible at low tide)

Question 51

What is an example of caves, arches, stacks and stumps

Answer 51

Old Harry Rocks, Isle of Purbeck