Glacial Outburst Floods and Larsen B

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Questions and Answers

What natural event is particularly associated with Larsen B ice shelf's instability?

Avalanches

Glacial outburst floods (correct)

Landslides

Earthquakes

What significant change occurred to Larsen B between January 31 and March 7, 2002?

3,250 square kilometers of ice broke off (correct)

It formed new icebergs

It became thicker

It was completely submerged

Which factor contributed to the collapse of Larsen B ice shelf?

Increased snowfall

Earth's alignment

Warm water currents (correct)

Global cooling

What would be the potential impact of a complete melt of the Greenland Ice Sheet?

7-8 meters of sea-level rise Signup and view all the answers

Which part of the Antarctic Ice Sheets is known to contain the majority of the world's ice?

East Antarctic Ice Sheet Signup and view all the answers

How did the presence of meltwater affect the Larsen B ice shelf?

It disintegrated the ice shelf Signup and view all the answers

What characterizes a niche glacier?

It occupies gullies and hollows on pole-facing slopes. Signup and view all the answers

What is the relationship between the North and South Patagonian Ice Fields during the Last Glacial Period?

They were joined together Signup and view all the answers

What is diamictite primarily composed of?

Poorly sorted particles of varying sizes Signup and view all the answers

Which process primarily creates features associated with glacial landscapes?

Erosion and Deposition Signup and view all the answers

What is the average thickness of the Greenland Ice Sheet?

2.1 km Signup and view all the answers

What distinguishes a drumlin from other glacial formations?

It has a tapered end indicating glacier flow direction. Signup and view all the answers

How are dropstones formed?

By icebergs releasing larger irregular sediments in water. Signup and view all the answers

What term refers to all sedimentary deposits of glacial origin?

Drift Signup and view all the answers

What do glacial erratics indicate?

They show the direction of glacial flow when compared to source rocks. Signup and view all the answers

What type of sedimentary rock forms from till or moraines in glacial contexts?

Diamictite Signup and view all the answers

What primarily characterizes an outwash plain?

A broad area of glacially eroded and sorted sediment transported by meltwater. Signup and view all the answers

What distinguishes a U-shaped valley from a V-shaped valley?

U-shaped valleys result from glacial erosion, while V-shaped valleys are formed by water erosion. Signup and view all the answers

What are striations in the context of glacial activity?

Long grooves cut into bedrock that indicate glacial movement direction. Signup and view all the answers

Which of the following best describes a roche moutonnée?

A smooth bedrock feature with both rough and smooth sides, shaped by a glacier. Signup and view all the answers

What is the primary method of sediment transport in ice rafting?

Icebergs transporting and dropping sediments into water. Signup and view all the answers

Which process involves the glacier freezing onto valley sides and pulling away rock?

Plucking Signup and view all the answers

What does the term 'entrainment' refer to in glacial processes?

The picking up of loose material by a glacier from the bed and valley sides. Signup and view all the answers

How are whalebacks similar to roche moutonnée?

Both are landforms that have been eroded by glaciers. Signup and view all the answers

What characterizes ice streams within ice caps and ice sheets?

They have substantially increased rates of flow over 500-1000 meters per year. Signup and view all the answers

Which of the following best describes a tidewater glacier?

A glacier that calves icebergs at high rates and terminates in water. Signup and view all the answers

What is the main distinction between ice caps and ice sheets?

Ice sheets are always larger than ice caps. Signup and view all the answers

What role do ice shelves play in relation to outlet glaciers?

They provide buttressing, which helps control mass balance. Signup and view all the answers

What distinguishes a distributary glacier from a tributary glacier?

Distributary glaciers split apart from a main glacier. Signup and view all the answers

Which of the following statements is true regarding hanging glaciers?

They are a type of valley glacier that ends at a hanging valley. Signup and view all the answers

What common feature is associated with tidewater glaciers?

They can create hazards for oceangoing vessels due to icebergs. Signup and view all the answers

What happens to an ice shelf that undergoes significant melting?

It may break away and disappear, as seen with Larsen B. Signup and view all the answers

What event is associated with the initiation of the Huronian glaciation?

The Great Oxygenation Event Signup and view all the answers

Which gas was primarily oxidized after the Great Oxygenation Event, contributing to a cooler climate?

Methane Signup and view all the answers

What is one proposed cause for the end of the Huronian glaciation?

Volcanic activity Signup and view all the answers

Which type of climate condition is more likely to have occurred during the Marinoan glaciation?

Total glaciation of the planet Signup and view all the answers

What phenomenon is described by the term 'Snowball Earth'?

A time when entire Earth was covered in ice Signup and view all the answers

What contributes to the cyclical nature of glaciation periods during the Huronian glaciation?

Volcanic activity releasing greenhouse gases Signup and view all the answers

How did the Great Oxygenation Event affect life forms on Earth at the time?

It led to a substantial extinction event Signup and view all the answers

Which glaciation is more likely considered less extensive despite lasting longer?

Marinoan Glaciation Signup and view all the answers

Study Notes

Glacial Events and Phenomena

Jökulhlaups are glacial outburst floods triggered by volcanic activity.
Larsen B, an ice shelf previously stable for millennia, collapsed between January and March 2002, losing approximately 3,250 square kilometers of ice.
Post-collapse, parts of Larsen B rapidly vanished due to warm water currents eroding its underside, making it unstable since at least 1995.
The 2002 collapse was exacerbated by meltwater pooling in cracks, which further advanced the disintegration.

Ice Fields and Sheets

The North and South Patagonian Ice Fields are among the largest globally, situated in the Andes of Argentina and Chile; the South Patagonian is larger.
During the Last Glacial Period, the two ice fields merged, covering almost all of southern Chile.
Greenland Ice Sheet, covering about 80% of Greenland, is the second largest after Antarctic Ice Sheet; a complete melt could raise sea levels by 7-8 meters.
The East Antarctic Ice Sheet contains about 4/5ths of the world's ice and is nine times larger than the West Antarctic Ice Sheet.

Glacier Types

Ice sheets (>50,000 sq.km) and ice caps are both classified as continental glaciers.
Ice streams exhibit increased flow rates (500-1000 meters/year), crucial for the mass balance of glaciers.
Tidewater glaciers terminate in water, calving into icebergs; ice tongues rapidly extend into the sea.
Ice shelves form from glaciers flowing into oceans, influencing the stability and mass balance of outlet glaciers.

Glacial Geology

Glacial deposition creates unique geological features through processes including erosion and sediment transport.
Diamictite is a sedimentary rock made from unsorted particles, commonly formed from glacial till.
Drift encompasses all glacially-originated sediment, while dropstones result from icebergs depositing larger sediments into marine environments.
Drumlins are streamlined hills formed by glacial movement, indicating the direction of flow.

Specific Features and Processes

Roche moutonnée is a smooth hill formed by glacier action, often marked by striations that indicate glacial movement.
U-shaped valleys, resulting from glacial erosion, contrast with V-shaped valleys formed by water.
Entrainment describes the process of glaciers picking up loose material through basal ice freezing and ice rafting.

Historical Glaciation Events

The Great Oxygenation Event led to significant glaciation, linked to the appearance of photosynthesizing cyanobacteria.
The Huronian glaciation involved cyclical glacial and interglacial periods, likely influenced by volcanic activity.
Cryogenian Snowball Earths were major glaciations where icy conditions covered most of the planet, with debate over the extent of glaciation during these periods.

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Description

This quiz explores the phenomenon of jökulhlaups, or glacial outburst floods, especially in the context of volcanic activity in Iceland. It also covers the significant events surrounding the collapse of the Larsen B ice shelf in Antarctica in 2002. Test your knowledge on these critical environmental changes and their implications.