--- title: "Glaciers & ice sheets" description: "Understand how accumulated snow becomes dense glacier ice that moves under its own weight. Explain how glaciers wear away valleys and leave moraines. Greenland and Antarctica have large ice sheets on " canonical: https://lightmysky.com/learn/science/glaciers-and-ice-sheets-mt_5_kErPeeNu source: https://lightmysky.com/learn/science/glaciers-and-ice-sheets-mt_5_kErPeeNu.md retrieved: 2026-11-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Glaciers & ice sheets Understand how accumulated snow becomes dense glacier ice that moves under its own weight. Explain how glaciers wear away valleys and leave moraines. Greenland and Antarctica have large ice sheets on land. Their complete melting would raise global sea level by about 65 metres. Ice cores preserve past air and clues about temperature; some Antarctic records span 800,000 years. Subject: Science · Area: Polar Regions · Ages 9 to 11 Page: https://lightmysky.com/learn/science/glaciers-and-ice-sheets-mt_5_kErPeeNu ## Ready when they can - Describe how glaciers form: snow accumulates, compresses, and becomes dense ice that flows slowly under its own weight - Explain that the Greenland and Antarctic ice sheets hold enough water to raise sea levels dramatically if melted - Describe how ice cores reveal climate history through trapped air bubbles from hundreds of thousands of years ago ## Lesson: Glaciers: rivers of ice You have seen how snow becomes ice. A glacier is a large mass of ice on land that moves under its own weight. It forms where more snow builds up than melts away. New snow presses older snow into dense ice. Gravity pulls thick ice downhill. Ice slowly changes shape inside the glacier. Some glaciers also slide over the ground beneath them. *(drawing: Snow left from earlier years is buried and pressed by newer layers.)* Moving ice and the rocks it carries wear away valley floors and sides. This often makes a broad U-shaped valley. Glaciers also carry rock and soil. Piles of this material deposited by a glacier are called moraines. A glacier can change land over many years even when its movement is slow. An ice sheet is a glacier covering a huge land area. Earth's two ice sheets are in Greenland and Antarctica. Complete melting would raise global sea level by about 65 metres. Rounded estimates are 7 metres from Greenland and 58 from Antarctica. Combine estimates by adding their values. This is not a forecast for a particular year. *(drawing: Complete-melt estimates in metres: Greenland about 7, Antarctica about 58. These are not predictions for a particular year.)* Scientists drill cylinders called ice cores from glaciers and ice sheets. Air bubbles sealed as snow becomes ice preserve samples of past air. Scientists measure gases such as carbon dioxide in them. The ice itself holds clues about past temperatures. Deeper layers are usually older, though ice movement can disturb them. Some Antarctic ice-core records span 800,000 years. Different cores cover different times. **Example.** To find half an age, divide by 2. Half of 600,000 years is 300,000 years. Check by adding two equal halves: 300,000 + 300,000 = 600,000. A sample's age alone does not tell us its exact depth. **Recap.** Glaciers form from packed snow and move under their own weight. They shape valleys and leave moraines. Ice sheets store water on land. Ice cores preserve clues about past air and climate. *This lesson, practice and flashcards were written for this dataset.* ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Ice & States of Matter](https://lightmysky.com/learn/science/ice-and-states-of-matter-mt_scbDHJZZHK) ## Opens up - [Earth's Frozen Water](https://lightmysky.com/learn/science/earths-frozen-water-mt_cMmG8VLbAp) - [Climate change at the poles](https://lightmysky.com/learn/science/climate-change-at-the-poles-mt_Fqna9qHffr)