PG Chapter 19: Glacial Landforms

What are the two main types of glaciers?

Continental ice sheets and mountain glaciers.

Where do continental ice sheets primarily exist?

In non-mountainous areas, such as Antarctica and Greenland.

What is a cirque?

A sheltered depression at the head of a stream valley where an alpine glacier originates.

What is the Pleistocene glaciation?

A period that began 2.59 million years ago, characterized by alternating glacial and interglacial periods.

What is the significance of the last major ice retreat?

It occurred 9,000 years ago and marked the end of the last glacial period.

How is glacial ice formed?

Snow compresses into granular form, which coalesces into névé/firn, and further compression results in glacial ice.

What determines glacier stability?

the balance between accumulation (gaining snow and ice) and ablation (loss of ice through melting or calving).

What is glacial plucking?

The process of picking up rock material through the refreezing of meltwater.

What are moraines?

Landforms consisting primarily of till, which is rock debris deposited by moving or melting ice.

What is a terminal moraine?

A moraine that marks the outermost limit of glacial advance.

What is a recessional moraine?

A moraine that indicates positions where the ice front is stabilized during retreat.

What are glaciofluvial features?

Features produced by deposition from ice-sheet meltwater, including outwash plains and eskers.

What is a tarn?

A depression that holds water after cirque ice melts away.

What is an arête?

A ridge formed by the erosion of several cirques cutting back into an interfluve.

What is the role of meltwater in glacier movement?

it contributes a surface for the glacier to slide on and lubricates the moving ice.

What are the characteristics of U-shaped glacial troughs?

They are formed by the deepening, steepening, and widening of valleys by glaciers.

What is permafrost?

Frozen ground that can exist in regions like Alaska, Canada, and Russia, often extending to great depths.

What is the current extent of ice cover on Earth?

About 10% of total land surface, with 96% of it located in Greenland and Antarctica.

How does climate change affect contemporary glaciation?

It leads to the retreat of polar ice caps and shrinking ice caps, which are indicators of a warming climate.