Enquiry Question 1 - Key Idea 2

Question 1

What is Key point 2?

Answer 1

Geological structure influences the development of coastal landscapes at a variety of scales.

Question 2

What does geological structure include?

Answer 2

It refers to the arrangement of rocks in 3D. It includes
- strata
- deformation
- faulting

Question 3

Strata

Answer 3

The different layers of rock within an area and how they relate to each other

Question 4

Deformation

Answer 4

The degree to which rock units have been deformed (tilted or folded) by tectonic activity

Question 5

Faulting

Answer 5

the presence of major fractures that have moved rocks from their original positions

Question 6

What two coastlines do geological structure form?

Answer 6

• concordant
• discordant

Question 7

What is a concordant coastline?

Answer 7

Coastlines where one rock type runs parallel to a stretch of coastline

Question 8

What are discordant coastlines?

Answer 8

Coastlines where alternating strata of differing rock types run perpendicular to the coastline

Question 9

What is morphology?

Answer 9

The shape of the landscape features. It is influenced by geological structure (headlands and bays, Dalmatian and Haff).

Question 10

What landforms are formed along a concordant coastline?

Answer 10

• Dalmatian coastline
• Coves
• Haff coastlines

Question 11

Formation of Haff coastlines:
CC

Answer 11

1. During the last glacial period (Devensian), the sea level was about 100m lower than today as water was retained in huge ice sheets.
2. Meltwater rivers on land beyond the ice front deposited thick layers of sand and gravel, creating outwash plains. The deposition produced geological structure parallel to the coastline.
3. In the Holocene, 12,000 yrs ago, Interglacial constructive waves pushed the ride of sands and gravel landwards as sea levels rose.
4. Sand ridges formed bars across some bays and river mouths with trapped river water- forming a lagoon behind, called Haffs.

Question 12

Formation of Dalmation Coast
CC

Answer 12

1. Two tectonic plates push towards each other, compressing the crust to create folds.
2. The folds have anticlines and synclines
3. Post glacial sea level rise has submerged the synclines leaving the anticlines sticking up parallel to the coast.

Question 13

Formation of Lulworth Cove
CC

Answer 13

1. It is on a landscape of alternating bands of geology that lay parallel to the coastline, horizontally organised.
2. Weaknesses in the layered rock (clay) are exposed to marine processes so are targeted and broke down by erosional processes.
3. The cove is formed out of the landscape after it gets behind the clay.
   It is unable to erode further due to the different type of rock behind it (chalk)

Question 14

2 examples of a Discordant coastline

Answer 14

• Swanage Bay
• West Cork, Ireland

Question 15

Formation of Swanage Bay
DC

Answer 15

1. There are alternating bands of rock types (hard and soft) perpendicular to the coast.
2. This is significant due to there being different levels of erosion
3. The headland absorbs all the wave energy due to wave refraction
4. As the wave gets more shallow, the wave experiences friction with the sea bed and breaks.
5. Wave refraction occurs once headlands and bays exist because the headlands cause the wave to break due to the shallower water around them.
6. Handlands absorb wave energy
7. Rates of erosion are drawn towards the headlands; deposition occurs inside the bay - making a beach

Question 16

Formation of West Cork, Ireland
DC

Answer 16

1. Limestone eroded by waves but also verticle fluvial processes in the past creating a river valleyin the Bantley Bay coastline - (now inundated)
2. As sea levels have risen, the river valley has been submerged - making the bay long and narrow
3. Rivers eroded the softer rocks to form valleys
4. Rising sea levels drowned the valleys
5. Since then, marine erosion has continued to erode headlands and bays forming a Ria

Question 17

West Cork, Ireland coastline description:

Answer 17

• South west of the UK
• Waves are more powerful
• It faces Bantry Bay, where it experiences high wave energy due to waves travelling through the Atlantic ocean with a large fetch

Question 18

Holocene:

Answer 18

The geological epoch that began about 12,000 years ago at the end of the last Pleistocene ice age. Its early stages were marked by large sea level rises of about 35m and a warming interglacial climate.

Question 19

How are coastlines ‘smoothed’ over time?

Answer 19

Because headlands are eroded more than the bays. This happens when:
- in deep water wave crests are parallel
- as waves approach the shallower water offshore of a headland, they slow down and wave height increases
- in bays - wave crests curve to fill the bay and wave height decreases
- the straight wave crests refract, becoming curved, spreading out in bays and concentrating on headlands
- the overall effect of wave refraction is to concentrate powerful waves at headlands (meaning greater erosion) and create lower, diverging wave crests in bays, reducing erosion

Question 20

What are cliff profiles influenced by:

Answer 20

• the resistance of the rock to erosion
• the dip of rock strata in relation to the coastline

Question 21

Dip:

Answer 21

the angle of rock strata in relation to the horizontal

Question 22

Horizontal dip:

Answer 22

Vertical or near vertical profile with notches reflecting strata that are more easily eroded

Question 23

Seaward dip, high angle:

Answer 23

Sloping, low angle profile with one rock layer facing the sea
- vulnerable to rock slides down the dip slope

Question 24

Seaward dip, low angle:

Answer 24

Profile may exceed 90* producing areas of overhanging rock
- very vulnerable to rock falls

Question 25

Landward dip:

Answer 25

Steep profiles of 70-80 producing a very stable cliff with reduced rock falls

Question 26

Faults

Answer 26

Major weaknesses within rock layers in the Earth’s crust, often due to significant movement.

Question 27

Joints:

Answer 27

Fractures/cracks in the Earth’s crust along with where has been no significant movement parallel to the fracture plane

Question 28

Fissures:

Answer 28

Narrow/elongated cracks in rock or openings in the Earth’s crust. Erosion can exploit these cracks.

Question 29

Folding:

Answer 29

When rocks experience compressional forces that cause them to bend and warp.
This can be a result of tectonic plate movement.
Folding can lead to opening up joints in rock.

Question 30

Two basic types of folding:

Answer 30

• Anticlines
• Synclines

Question 31

Anticline folds:

Answer 31

Convex up (A shaped)

Question 32

Syncline folds:

Answer 32

Concave down (U shaped)