Unit 8 - Essay Questions - Sea Levels

What is eustatic sea level change?

• A local rise or fall in land level

• A worldwide change in sea level due to climate change

• A temporary sea level change caused by tides

• A rise in sea level due to an earthquake

Answer explanation

✅ Answer: B) A worldwide change in sea level due to climate change
💡 Explanation:
Eustatic change means that sea levels rise or fall across the whole world, usually due to climate changes like glacial melting or thermal expansion of seawater.
🌍 Example: During the last ice age, sea levels were much lower because a lot of water was trapped in ice sheets.

Which process causes isostatic sea level change?

• Melting glaciers and thermal expansion of water

• The movement of tectonic plates

• The sinking or rising of land due to the weight of ice sheets

• Increased sediment deposition on coastlines

Answer explanation

✅ Answer: C) The sinking or rising of land due to the weight of ice sheets
💡 Explanation:
When glaciers melt, land rebounds (rises) because the weight of the ice is gone. This isostatic uplift happens locally, not globally.
🌍 Example: Scotland is rising due to isostatic rebound, while Southern England is sinking slightly.

What landform is created when sea level falls and leaves behind former shorelines?

• Ria

• Raised beach

• Spit

• Barrier island

Answer explanation

✅ Answer: B) Raised beach
💡 Explanation:
A raised beach forms when sea levels drop, leaving old beaches high above the current sea level.
🌍 Example: Portland Raised Beach (Dorset, UK) is an ancient beach now sitting 15m above modern sea level.

Which of the following is an example of a drowned river valley?

• Portland Raised Beach

• Kingsbridge Estuary

• Chesil Beach

• Holderness Coast

Answer explanation

✅ Answer: B) Kingsbridge Estuary
💡 Explanation:
A ria is a drowned river valley caused by rising sea levels. It looks like a long, flooded valley.
🌍 Example: Kingsbridge Estuary (Devon, UK) – a former river valley now flooded by rising seas.

What evidence at Portland Raised Beach suggests past sea level change?

• Sand dunes and salt marshes

• Rounded pebbles and wave-cut notches

• Coral reefs and mangroves

• Active cliff erosion and rockfalls

Answer explanation

✅ Answer: B) Rounded pebbles and wave-cut notches
💡 Explanation:
The presence of rounded pebbles (from past wave action) and notches cut into cliffs show that waves once reached this level.
🌍 Example: Portland Raised Beach has pebbles left from when the sea was 15m higher than today.

Which factor affects sea level change on a global scale?

• Longshore drift

• Local tectonic uplift

• Glacial melting and thermal expansion

• Wave refraction patterns

Answer explanation

✅ Answer: C) Glacial melting and thermal expansion
💡 Explanation:
When ice caps melt or ocean water expands due to warming, sea levels rise globally.
🌍 Example: Greenland and Antarctica’s ice melt is causing global sea levels to rise.

What type of landform is a fjord?

• A submerged glacial valley

• A barrier beach

• A lowland delta

• A depositional spit

Answer explanation

✅ Answer: A) A submerged glacial valley
💡 Explanation:
A fjord is a steep, deep valley flooded by the sea, created when glaciers carve through rock.
🌍 Example: Sognefjord (Norway) is a famous fjord formed by glacial erosion.

Which of the following is NOT a factor in forming coastal landforms?

• Rock type and structure

• Human activity

• The Earth's magnetic field

• Wave action

Answer explanation

✅ Answer: C) The Earth's magnetic field
💡 Explanation:
Magnetism does not affect landform formation, but waves, rock type, and human activities do.
🌍 Example: Waves erode cliffs, forming features like wave-cut platforms.

How does isostatic rebound affect coastal landforms?

• It submerges land, forming new estuaries

• It causes land to rise, leaving raised beaches

• It forms spits and bars by shifting sediments

• It leads to rapid coastal erosion from storm surges

Answer explanation

✅ Answer: B) It causes land to rise, leaving raised beaches
💡 Explanation:
As glaciers melt, land rises, exposing old coastlines.
🌍 Example: Scotland’s raised beaches were formed this way.

What is the primary cause of rising global sea levels today?

• Increased volcanic activity

• Deforestation

• Climate change and glacial melting

• Tectonic plate movement

Answer explanation

✅ Answer: C) Climate change and glacial melting
💡 Explanation:
Warmer temperatures melt glaciers and cause seawater to expand, leading to sea level rise.
🌍 Example: Low-lying countries like the Maldives are at risk of being submerged.