Unit 8 - Page 243 - 248

1. What is bioconstruction in coastal environments?

• The natural process of waves shaping coastal cliffs

• The formation of landforms through biological activity, such as coral reefs and mangroves

• The artificial construction of coastal defenses by humans

• The process of glaciers shaping coastlines

Answer explanation

Explanation: Bioconstruction happens when living organisms, like coral or mangroves, help build coastal landforms by trapping sediments and creating habitats.
Example: Coral reefs grow over time, providing a natural barrier against waves and storms.

Which of the following is an example of a bioconstruction process?

• Formation of fjords

• Tectonic uplift of coastlines

• Growth of mangrove forests

• Erosion of cliffs by wave action

Answer explanation

Explanation: Mangroves trap sediment with their roots, helping to build up coastal land.
Example: The Sundarbans in India and Bangladesh have vast mangrove forests that protect the coast from erosion and storms.

What is eustatic sea-level change?

• A local change in sea level due to land rising or sinking

• A global change in sea level due to variations in the amount of water in the oceans

• A change in sea level caused by sediment deposition

• A change in sea level due to volcanic activity

Answer explanation

Explanation: When glaciers melt or ice sheets grow, the total amount of water in the oceans changes, causing sea levels to rise or fall globally.
Example: During the Ice Age, water was trapped in glaciers, lowering global sea levels.

What causes eustatic sea-level changes?

• Melting and growth of glaciers and ice sheets

• Local tectonic activity

• Erosion of coastal cliffs

• Changes in river sediment supply

Answer explanation

Explanation: More ice means lower sea levels; melting ice adds water, raising sea levels worldwide.
Example: The melting of Antarctica’s ice sheets contributes to rising global sea levels.

What is isostatic adjustment (isostacy)?

• The process of land rising or sinking due to the redistribution of Earth's mass

• The movement of tectonic plates in coastal regions

• The gradual sinking of deltas due to sediment compaction

• The process by which waves shape the coastline

Answer explanation

Explanation: When glaciers melt, the land that was pressed down by ice slowly rises back up.
Example: Parts of Scandinavia are still rising today because the land was compressed by ice during the last Ice Age.

Which of the following can cause isostatic adjustment?

• The melting or formation of large ice sheets

• Human construction on coastal areas

• Increase in storm frequency

• Coral reef growth

Answer explanation

Explanation: Heavy glaciers push land down; when they melt, the land slowly lifts.
Example: Scotland is rising slightly each year as a result of ice loss from the last Ice Age.

What is the difference between eustatic and isostatic sea-level change?

• Eustatic change is global, while isostatic change is local

• Isostatic change is caused by tectonic activity, while eustatic change is caused by sediment deposition

• Eustatic change affects only ocean basins, while isostatic change affects only river deltas

• There is no difference; they mean the same thing

Answer explanation

Explanation: Eustatic change affects the entire ocean; isostatic change only affects specific regions.
Example: The whole world experiences sea-level rise from global warming (eustatic), but some places (like Scandinavia) are rising locally due to isostatic rebound.

Which coastal landform is a result of isostatic uplift?

• Mangrove forests

• Raised beaches

• Barrier islands

• Coral reefs

Answer explanation

Explanation: When land rises after being pressed down by ice, old beaches that were once at sea level are now found higher up.
Example: The Portland raised beach in England shows where the sea level used to be.

What is a ria?

• A coastal inlet formed by the drowning of a river valley due to sea-level rise

• A deep, glacially carved valley flooded by the sea

• A sandbar that separates a lagoon from the ocean

• A coastal feature created by coral reef growth

Answer explanation

Explanation: When sea levels rise, river valleys flood, forming long, narrow inlets.
Example: The rias along the coast of Spain, like the Ría de Vigo.

Rias are typically found in which type of coastline?

• Emergent coastlines

• Submergent coastlines

• Depositional coastlines

• Erosional coastlines

Answer explanation

Explanation: Submergent coastlines form when land sinks or sea levels rise, flooding valleys.
Example: The rias in southwest England, like the Kingsbridge Estuary.