Glacial Landforms and Deposits Quiz

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Questions and Answers

What is the cryosphere and what percentage of the Earth's surface do glaciers cover today?

The cryosphere is the part of the Earth that remains below the freezing point of water, and glaciers cover about 10% of the Earth's surface today.

When did the most recent glaciation occur and how long ago did it end?

The most recent glaciation occurred during the Pleistocene Epoch between 1.8 million years ago and 11,000 years ago, ending only 10,000 years ago.

What is the definition of a glacier?

A glacier is a permanent (on a human time scale) body of ice, consisting largely of recrystallized snow, that shows evidence of downslope or outward movement due to the pull of gravity.

In which geological periods did other glaciations occur?

Other glaciations occurred in the Permian, Ordovician, and Late Precambrian periods. Signup and view all the answers

Explain the potential causes of long-term variations in climate, and how they may lead to glaciations on a single continent.

Long-term variations in climate on a single continent are likely caused by drifting continents. If a continent drifts toward the equator, the climate will become warmer. If the continent drifts toward the poles, glaciations can occur on that continent. Signup and view all the answers

Discuss the astronomical factors that contribute to periodic glacial-interglacial cycles.

Astronomical factors such as variations in the eccentricity of the Earth's orbit, the tilt of the Earth's axis, and the way the Earth wobbles on its axis (precession) contribute to periodicities (Milankovitch Cycles) similar to those observed for glacial-interglacial cycles. Signup and view all the answers

Explain the potential impacts of changes in oceanic circulation on global climate and glacial-interglacial cycles.

Small changes in ocean circulation can amplify small changes in temperature variation produced by astronomical factors, potentially impacting global climate and contributing to glacial-interglacial cycles. Signup and view all the answers

Describe the role of atmospheric factors, such as greenhouse gas concentrations and dust content, in influencing global climate and glaciations.

During past glaciations, lower greenhouse gas concentrations and higher dust content in the atmosphere were observed. These conditions may have played a role in causing or being caused by the ice ages, influencing global climate and glaciations. Signup and view all the answers

What landforms are created by glacial processes?

Various landforms created by glacial processes include kames, eskers, and meltwater lakes. Signup and view all the answers

How do glacial ice loading and melting affect the lithosphere?

Glacial ice loading depresses the lithosphere, causing it to rebound after the ice melts. Signup and view all the answers

What provides insight into past ocean temperatures and glacial-interglacial cycles?

Oxygen isotope studies in deep-sea sediments provide insight into past ocean temperatures and glacial-interglacial cycles. Signup and view all the answers

How long have each glacial-interglacial cycle lasted in the past 1 million years?

Each glacial-interglacial cycle in the past 1 million years has lasted about 100,000 years. Signup and view all the answers

Explain the different types of glaciers and their characteristics.

Glaciers can occupy various formations, including cirque glaciers, valley glaciers, fjord glaciers, piedmont glaciers, and ice caps. Ice Sheets (Continental glaciers) cover large areas of the land surface, with Greenland and Antarctica comprising about 95% of all glacial ice currently on Earth. Greenland ice sheet is over 3000 m thick, and Antarctica is covered by two large ice sheets. Ice shelves are sheets of ice floating on water and attached to land, reaching thicknesses of 1000 m and extending hundreds of km from land. Glaciers can be classified into temperate glaciers, with ice near its melting point, and polar glaciers, with ice well below its melting point. Signup and view all the answers

What are the necessary conditions for the formation of glaciers?

Three conditions are necessary to form a glacier: cold local climate, abundant snowfall, and snow not being removed by avalanches or wind. Signup and view all the answers

How do glaciers change in size and what processes contribute to their movement?

Glaciers can change in size through accumulation (addition of snowfall) and ablation (loss of mass resulting from melting). Glaciers move to lower elevations under the force of gravity by internal flow (deformation of ice crystal structure) and basal sliding (meltwater reducing friction). Signup and view all the answers

What are the main features of glacial landscapes and what processes contribute to their formation?

Glacial landscapes are the result of both glacial erosion and glacial deposition, with glaciers eroding through abrasion, plucking, and melting by pressure against the up-ice side of an obstruction. Glaciated landscapes are a result of glacial erosion and deposition, with glaciers transporting and depositing material. Glacial movement can pluck away bedrock chunks and erode the land surface. Signup and view all the answers

Explain the formation of glacial striations and glacial polish, and their significance in glacial geology.

Glacial striations are long parallel scratches and grooves formed at the bottom of temperate glaciers by rocks scraping against the underlying rock. Glacial polish is rock with a smooth surface produced by fine-grained material embedded in the glacier acting like sandpaper. These features are significant in glacial geology as they provide evidence of past glacial movement and direction, helping scientists understand the history of glacial activity in an area. Signup and view all the answers

Describe the formation and characteristics of cirques, and explain their role in shaping mountain landscapes.

Cirques are bowl-shaped depressions at the heads of mountain glaciers, often containing small lakes called tarns. They are formed through the erosive action of glaciers and frost wedging. Cirques play a crucial role in shaping mountain landscapes by initiating the formation of other glacial landforms such as arêtes, horns, and hanging valleys through their erosive processes. Signup and view all the answers

Distinguish between the 'U' shape of glacial valleys and the 'V' shape of stream-eroded valleys, and explain the processes responsible for their formation.

Glacial valleys have a 'U' shape in cross-section due to glacial erosion, as opposed to the 'V' shape from stream erosion. The 'U' shape is formed through the abrasive action of glacial ice and debris, while the 'V' shape of stream-eroded valleys is primarily due to the erosive force of flowing water. These distinct shapes reflect the different processes of erosion and deposition associated with glaciers and rivers. Signup and view all the answers

Discuss the formation of fjords and their connection to past glacial activity, providing examples of regions with prominent fjords.

Fjords are narrow inlets along the seacoast that were once occupied by valley glaciers. They are formed through the deepening of U-shaped glacial valleys by the advance and retreat of glaciers, resulting in submerged valleys that become fjords. Prominent examples of fjords can be found in regions such as Norway, Alaska, New Zealand, and Chile, where past glacial activity has left a lasting geographical imprint in the form of these distinctive coastal features. Signup and view all the answers

Flashcards

What is the cryosphere?

The part of Earth's surface that remains frozen, including glaciers, ice sheets, and sea ice.

What percentage of Earth's surface is covered by glaciers?

Glaciers cover about 10% of Earth's surface.

When was the most recent glaciation?

The most recent glacial period was the Pleistocene Epoch, lasting from 1.8 million to 11,000 years ago.