Glaciology

Glaciology is the scientific study of glaciers and ice. It comes from the Latin word glacies meaning "frost, ice" and the Ancient Greek word logos meaning "subject matter." This field looks at how ice behaves in nature.

Glaciology is part of Earth science and brings together many different areas of study. It includes geophysics, geology, physical geography, geomorphology, climatology, meteorology, hydrology, biology, and ecology. Because glaciers affect people and communities, glaciology also touches on human geography and anthropology.

Recently, scientists have found water ice on places like the Moon, Mars, Europa, and Pluto. This has added a new space-related part to the field, called "astroglaciology." Studying ice helps us understand our planet and others in space.

Overview

A glacier is a large mass of ice that forms when snow falls and piles up over many years. Glaciers move very slowly, either down from high mountains or spreading out from places where lots of snow collects, like in big icy areas.

Glaciology is the study of glaciers and ice. It looks at how glaciers change over time and their effects on the land. People who study glaciers are called glaciologists, and they work together with scientists who study the Earth and its climate. This field is very important for understanding polar regions.

Types

Glaciers can be grouped by their shape and how they relate to the land around them. There are two main types: alpine glaciation and continental glaciation.

Alpine glaciers flow down mountain valleys like rivers of ice. They can change the shape of the land, creating deep valleys called cirques and sharp ridges called arêtes. Continental glaciers are huge sheets of ice found in very cold areas like Greenland and Antarctica. These glaciers can cover very large areas and make the land around them smoother.

Zones of glaciers

Glaciers have two main zones. The accumulation zone is where ice forms faster than it melts away. This happens when more snow falls and turns to ice each year than disappears.

The ablation zone is where melting, breaking off into the water, and evaporation happen more than new snow adds. In this zone, ice and snow melt away faster than they are replaced.

Accumulation zone – where the formation of ice is faster than its removal. Ablation (or wastage) zone – when the sum of melting, calving, and evaporation (sublimation) is greater than the amount of snow added each year.

Glacier equilibrium line and ELA

The glacier equilibrium line is the line that separates the part of a glacier where snow builds up from the part where snow melts away. The height of this line, called the equilibrium line altitude (ELA), changes over time and helps scientists understand how healthy a glacier is. By watching the ELA for many years, we can learn about climate change.

Movement

When a glacier gains more snow or refreezing rain than it loses through melting or breaking off, it grows bigger and moves forward. If it loses more ice than it gains, the glacier will shrink. Sometimes, a glacier can move much faster than usual, which is called a surging glacier. This can happen every 10 to 15 years, for example on Svalbard. This fast movement happens when extra snow builds up and causes melting at the bottom, allowing the glacier to slide quickly.

Rate of movement

Glaciers usually move very slowly, from a few centimeters to a few meters each day. How fast they move depends on several things:

• Temperature of the ice. Cold glaciers stay frozen to the ground, while glaciers that are at the melting point can slide on a thin layer of water.
• Gradient of the slope.
• Thickness of the glacier
• Water under the glacier

Glacial Terminology

Glaciers have special names for the different things that happen to them and the shapes they create.

• Ablation: This is when a glacier loses ice by melting, turning into vapor, or breaking off into the water as icebergs.
• Ablation zone: This is the part of a glacier where it loses more ice each year than it gains from new snow.
• Arête: A sharp ridge of rock where two circular valleys meet.
• Bergschrund: A deep crack near the top of a glacier where the ice has split apart.
• Cirque: A bowl-shaped valley carved out at the start of a glacier.
• Creep: The slow movement of ice at a tiny level when pressure is put on it.
• Flow: The steady movement of ice in one direction.
• Fracture: When ice breaks because it is moving too fast to adjust slowly.
• Glacial landform: Shapes and features made by glaciers on the land.
• Moraine: Rocks and dirt carried by a glacier and left behind at its sides or end.
• Névé: The upper part of a glacier where snow builds up.
• Nunatak: A peak of rock or a mountain that sticks up above the surrounding glacier.
• Horn: A tall, sharp peak formed when glaciers carve out valleys around a mountain.
• Plucking: When flowing ice pulls pieces of rock away from the ground.
• Tarn: A lake left behind in a cirque after a glacier melts.
• Tunnel valley: A long tunnel-like valley carved by moving ice, left behind when the ice disappears.

Glacial deposits

Glacial deposits are materials left behind by moving glaciers. Some of these deposits are layered, like outwash sand and gravel from the front of glaciers, kettles which are pits left when ice melts, eskers which are long ridges of sand and gravel, kames which are small steep hills, and varves which are thin layers of sediment from ancient lakes near glaciers.

Other deposits are not layered, such as till which is a mix of different sized materials left by glaciers, moraines which are piles of material deposited at the end, along the sides, or under the glacier, drumlins which are smooth stretched hills made of till, and ribbed moraines which are long hills formed under glaciers.