Glacial Movement and Landforms Overview

What causes basal sliding in glaciers?

Basal sliding occurs when the weight of ice increases pressure at the base, leading to warmth and meltwater that help move the glacier downhill.

What is rotational slip in glacial movement?

Rotational slip happens when snow accumulates in a shady hollow, compresses to firn, and gravity moves it downhill in a circular motion, potentially causing crevasses.

How does bulldozing occur in glacial movement?

Bulldozing occurs when ice from upland areas descends and bulldozes material to lowland areas, pushing soil and rocks with the force of moving ice.

What are the three types of ice erosion?

The three types of ice erosion are plucking, abrasion, and freeze-thaw weathering.

What is plucking in the context of glacial erosion?

Plucking is when ice moves over a rock surface, and meltwater freezes around loose sections, pulling them away.

How does abrasion contribute to glacial erosion?

Abrasion occurs when rocks scrape against the surface below the glacier.

What happens during freeze-thaw weathering?

Water seeps into cracks, freezes, expands by 10%, and exerts pressure that cracks the rocks, leading to erosion.

What is a moraine?

A moraine is the material carried by a glacier.

What is glacial outwash?

Glacial outwash is sediment carried by meltwater, which is rounded and reduced in size by attrition, with larger rocks deposited first at the glacier's end.

What is glacial till?

Glacial till is sediment carried by ice that has no attrition or abrasion, resulting in angular and unsorted rocks.

How are corries formed?

Corries form when snow accumulates in a shady hollow, compacts to firn, and ice moves downslope due to gravity and meltwater, eroding the hollow deeper and wider.

What is an arete?

An arete is a sharp ridge of rock formed when two corries erode back to back.

What defines a pyramidal peak?

A pyramidal peak is a sharp-edged mountain peak.

How are U-shaped valleys formed?

U-shaped valleys form when a glacier flows through a V-shaped valley, eroding it wide and deep through abrasion and plucking, resulting in steep sides and truncated spurs.

What are hanging valleys and how do they form?

Hanging valleys are formed when a tributary glacier widens and deepens a tributary valley, leaving it hanging above the main valley, often with a waterfall.

What are drumlins and their characteristics?

Drumlins are elongated hills, typically 30-40 meters high and 300-400 meters long, formed by till building up against an obstacle.

How are drumlins shaped?

Drumlins have a tapered end on the downstream side and a blunt end on the upstream side, formed as sediment is deposited over an obstacle.

What are erratics in glacial geology?

Erratics are rocks that differ from the bedrock they are found on, transported by glacial movement.

What is the role of meltwater in glacial movement?

Meltwater at the base of a glacier reduces friction, facilitating movement downhill.

What is the significance of differential erosion in hanging valleys?

Differential erosion occurs when the main glacier erodes the valley more than the tributary glacier, resulting in the tributary valley being left hanging.

What is the process of attrition in glacial outwash?

Attrition is the process where sediment is rounded and reduced in size as it is carried by meltwater.