Glaciers. Growth and contraction

06/05/2026

The online glacier simulations on this page will help you to better understand the dynamics of glaciers and how they increase or decrease in size.

This Thematic Unit is part of our Earth Sciences collection

Ablation

The total loss of ice and snow from a glacier due to melting, evaporation, or the calving of icebergs.

Continental Glacier

A massive ice sheet covering vast areas of a continent, obscuring the underlying terrain (e.g., Antarctica).

Cryosphere

Part of the Earth system that contains water in a solid state, including glaciers, sea ice, and snow.

Glacial Cirque

An amphitheater-shaped depression located at the head of a glacial valley, where the snow that feeds the glacier accumulates.

Glacial Erosion

Process of wearing down the Earth’s relief caused by the movement of ice and the dragging of rocky materials.

Glacier

A large mass of compressed ice that forms through snow accumulation and flows slowly under its own weight.

Glacier Tongue

The lower part of a glacier that extends down a valley, characterized by the movement of ice and the erosion of the bedrock.

Ice Sheet

A mass of glacial ice covering more than 50,000 km² of land and flowing in all directions (e.g., Antarctica and Greenland).

Moraine

Accumulation of sediment and rocks (till) transported and deposited directly by the movement of a glacier.

Mountain Glacier

A mass of ice confined by mountainous terrain, flowing from cirques into valleys; also called an alpine glacier.

Permafrost

A layer of soil or rock that remains continuously frozen for at least two consecutive years.

U-shaped Valley

A valley with a flat bottom and steep sides formed by the erosion of a tongue or valley glacier.

What are glaciers

Glaciers are ice masses formed by the accumulation and compression of snow over long periods of time. They are a fundamental part of mountain ecosystems and play a crucial role in the global climate balance. These large expanses of ice are found mainly in polar regions and high mountains.

Glacier movement

Glaciers form when snow accumulates faster than it melts. As more snow accumulates, pressure from the upper layers compresses the older snow, turning it into pack ice. Over time, this ice shifts under its own weight, creating a glacial flow.

Types of glaciers: mountain glaciers and cap glaciers

Mountain glaciers, also known as alpine glacier or valley glacier, are found in mountainous regions and flow down mountain slopes. Their size is relatively small compared to other types of glaciers and their movement is conditioned by the topography of the terrain. Typical examples of mountain glaciers are found in the Alps, the Andes and the Himalayas.

Continental glaciers, also called cap glaciers, are huge glaciers that cover large areas of land, regardless of the underlying topography. They flow in all directions from a center of ice accumulation and can cover continents, as in the case of Greenland and Antarctica.

Importance of glaciers

These impressive ice bodies harbor incredible biodiversity, with unique adaptations to survive in extreme conditions. Glaciers are home to diverse life forms, such as algae, lichens and small invertebrates. They also act as freshwater reservoirs, slowly releasing water into rivers and streams as they melt, which is essential for the survival of many ecosystems and human communities.

Ablation

The total loss of ice and snow from a glacier due to melting, evaporation, or the calving of icebergs.

Continental Glacier

A massive ice sheet covering vast areas of a continent, obscuring the underlying terrain (e.g., Antarctica).

Cryosphere

Part of the Earth system that contains water in a solid state, including glaciers, sea ice, and snow.

Glacial Cirque

An amphitheater-shaped depression located at the head of a glacial valley, where the snow that feeds the glacier accumulates.

Glacial Erosion

Process of wearing down the Earth’s relief caused by the movement of ice and the dragging of rocky materials.

Glacier

A large mass of compressed ice that forms through snow accumulation and flows slowly under its own weight.

Glacier Tongue

The lower part of a glacier that extends down a valley, characterized by the movement of ice and the erosion of the bedrock.

Ice Sheet

A mass of glacial ice covering more than 50,000 km² of land and flowing in all directions (e.g., Antarctica and Greenland).

Moraine

Accumulation of sediment and rocks (till) transported and deposited directly by the movement of a glacier.

Mountain Glacier

A mass of ice confined by mountainous terrain, flowing from cirques into valleys; also called an alpine glacier.

Permafrost

A layer of soil or rock that remains continuously frozen for at least two consecutive years.

U-shaped Valley

A valley with a flat bottom and steep sides formed by the erosion of a tongue or valley glacier.

Explore the exciting STEM world with our free, online, simulations and accompanying companion courses! With them you’ll be able to experience and learn hands-on. Take this opportunity to immerse yourself in virtual experiences while advancing your education – awaken your scientific curiosity and discover all that the STEM world has to offer!

Glacier simulations

Glacier movement

Adjust snowfall and temperature to see how the glacier grows and contracts. Use scientific tools to measure glacier thickness, velocity and accumulation.

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Isaac Newton

Charles Lyell

1797

–

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The architect of modern geology who proved that the Earth was sculpted by slow, gradual changes.

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Test your knowledge

What is a glacier, and how does it form over long periods of time?

A glacier is a large mass of ice formed when snow accumulates over many years in regions where temperatures remain low enough to prevent complete melting. As layers of snow build up, the weight of the upper layers compresses the lower ones, turning them into dense glacial ice. This ice is not static: under its own weight, it slowly flows downhill or outward, creating what is known as glacial movement. Glaciers are found mainly in polar regions and high mountains, where climatic conditions allow them to persist. They play a crucial role in the global climate system by storing vast amounts of freshwater and influencing sea levels. Studying glaciers helps scientists understand geological processes, climate change and the functioning of fragile ecosystems.

What types of glaciers exist, and how does their behavior influence ecosystems and climate?

Glaciers are generally classified into mountain glaciers and continental glaciers. Mountain glaciers, also known as alpine or valley glaciers, form in mountainous regions and flow downhill following the terrain. Although relatively small, they are vital for regulating water flow in rivers and sustaining local ecosystems. Continental glaciers, or ice caps, are massive ice sheets that cover large areas and flow outward from a central accumulation zone. Greenland and Antarctica are the best examples. These glaciers strongly influence global climate by reflecting sunlight and storing enormous amounts of water. Their advance or retreat affects sea levels, freshwater availability and the stability of sensitive ecosystems. Understanding their dynamics is essential for assessing the impacts of climate change and predicting future environmental transformations.

How does a glacier form, and why does it start moving?

A glacier forms when more snow falls than melts over many years. The snow builds up, gets compressed and eventually turns into solid ice. When the ice becomes thick enough, its own weight makes it slowly slide downhill. Even though it looks solid, ice can flow like a very slow, thick liquid. This movement is called glacial flow and is what makes glaciers advance through valleys or spread across large areas.

What is the difference between a mountain glacier and a continental glacier?

A mountain glacier forms in high, cold regions and moves down the slopes following the shape of the land. It is relatively small and strongly influenced by the terrain. A continental glacier, on the other hand, is enormous and can cover entire regions, such as Greenland or Antarctica. It does not follow a valley but spreads outward in all directions from a central accumulation point. Continental glaciers store huge amounts of water and have a global impact on climate and sea levels.

Why are glaciers important for the planet?

Glaciers act as giant freshwater reservoirs, releasing water gradually into rivers and ecosystems. They also reflect sunlight, helping regulate Earth’s temperature. In addition, they host unique life forms adapted to extreme conditions and preserve climate records in their ice layers. When glaciers melt too quickly, they can raise sea levels and reduce water availability for millions of people. Their health is a key indicator of global climate change.