1.7 Relatively Sinking

Question 1

Define a submergent coastline.

Answer 1

Sections of the littoral zone where sea level rise has now inundated areas that were previously part of the land, meaning they are now under water

This phenomenon occurs due to rising sea levels, leading to the submersion of coastal land.

Question 2

What are fjords?

Answer 2

Drowned glacial valleys - a section of a glacially eroded valley flooded by the sea

Fjords are characterized by steep cliffs and deep waters.

Question 3

What typically characterizes the entrance of a fjord?

Answer 3

A shallow entrance with a submerged bar formed by the ridge of deposition

This feature can affect water circulation and marine life.

Question 4

What is a ria?

Answer 4

A drowned river valley flooded by the sea

It is a section of river valley that becomes much wider than expected due to the sea.

Question 5

What originally made a ria?

Answer 5

Flooding of a river valley by the sea

This process results in a wider section of the river valley.

Question 6

Why is England’s south coast sinking?

Answer 6

Due to isostatic rebound in the north of the UK and the seesaw effect

This means that the UK is now lower than when the north was glaciated.

Question 7

What caused the emergent coasts to form?

Answer 7

A rapid 100 m eustatic rise in global sea levels at the start of the Holocene

This rise was due to the shrinking of ice sheets and glaciers over 3,000 years.

Question 8

Which regions experienced land rising out of the sea due to the formation of emergent coasts?

Answer 8

• Northern Britain
• Scandinavia

These areas were previously covered by ice and gradually rose as sea levels changed.

Question 9

What might you find on a raised beach?

Answer 9

• Possible previous wave cut platforms
• Usually vegetated by plant succession
• Further succession prevented due to grazing

Raised beaches are formed by the uplift of land or a drop in sea level, leading to the exposure of former beach areas.

Question 10

Why is tectonics considered important on coastlines?

Answer 10

It could be responsible for the geology type and for any uplift

Tectonic activity can significantly influence coastal landscapes and geological features.

Question 11

What are the two main causes of global sea-level rise?

Answer 11

• Thermal expansion
• Eustatic sea level change

These factors contribute to the overall increase in sea levels globally.

Question 12

What is isostatic rebound?

Answer 12

The rise of land masses that were previously compressed by ice sheets

This phenomenon occurs in some places and affects local sea levels.

Question 13

What is the role of tectonic subsidence in sea-level changes?

Answer 13

It contributes to sea-level rise in some regions

Tectonic activity can cause land to sink, affecting local sea levels.

Question 14

What is Eustatic sea-level rise?

Answer 14

Global sea-level rise

It refers to changes in sea level due to global factors.

Question 15

During which periods does Eustatic sea-level rise occur?

Answer 15

Glacial periods

Ice sheets are formed on high-latitude land during these times.

Question 16

What happens to evaporated water during glacial periods?

Answer 16

Locked up as ice

This results in less water in the sea.

Question 17

What occurs during interglacial periods?

Answer 17

Ice sheets on land melt

Melted water returns to the sea, causing sea-level rise.

Question 18

What is the effect of global temperatures on sea levels?

Answer 18

Causes thermal expansion

Water particles move faster and take up more space, increasing the volume of ocean water.

Question 19

Fill in the blank: Eustatic sea-level rise occurs when evaporated water is locked up as ice, leading to _______.

Answer 19

Less water in the sea

This is a key factor during glacial periods.

Question 20

What does isostatic refer to in the context of land and sea level?

Answer 20

The process where ice sheets melt and land surface slowly rebounds upwards, lifting the land surface out of the sea, making sea level appear to fall

This process occurs as the weight of glaciers is removed.

Question 21

During glacials, what happens to the land and sea level?

Answer 21

Land is compressed by the weight of glaciers, causing sea level to appear to rise

The compression leads to a temporary increase in sea level due to the weight of the ice.

Question 22

What occurs during interglacials that affects sea level?

Answer 22

• Ice melts
• Sediment is deposited in large river deltas
• Increased weight leads to ‘crustal sag’
• Delta subsidence

These factors contribute to the appearance of rising sea levels during interglacial periods.

Question 23

What causes submergent coasts?

Answer 23

Relative rise in sea-level

This rise changes the shape/form of the coastline.

Question 24

What results in an emergent coastline?

Answer 24

Relative fall in sea-level

Examples include offshore bars, raised beaches, and fossil cliffs.

Question 25

Name the **key factors** affecting coastlines.

Answer 25

* Wave types * Topography * Rock structure/disposition ## Footnote These factors influence the formation and characteristics of coastlines.

Question 26

What is **post glacial adjustment**?

Answer 26

The way in which the northern part of the USA/Canada is rebounding upwards while the southern part of the USA is tilting downwards ## Footnote This results in relative sea-level fall in the north and relative sea-level rise in the south.