---
title: "Glaciers & Ice Sheets"
description: "Understand how glaciers and ice sheets form and behave — snow accumulates over centuries and compresses into dense ice, glaciers flow slowly downhill under their own weight carving U-shaped valleys an"
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: 2026-10-19
---

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# Glaciers & Ice Sheets

Understand how glaciers and ice sheets form and behave — snow accumulates over centuries and compresses into dense ice, glaciers flow slowly downhill under their own weight carving U-shaped valleys and depositing moraines; the Greenland and Antarctic ice sheets together hold enough ice to raise sea levels by over 65 metres; and ice cores drilled from these sheets contain trapped air bubbles that reveal Earth's climate history going back 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

Every winter, snow falls on high mountains and near the poles. If summer never melts it all away, the snow piles up year after year. Layer after layer presses down on the snow below. After enough years, that weight squeezes the snow into something new: solid, dense ice. This packed ice is called a glacier, and once it gets thick and heavy enough, it starts to flow downhill, very slowly, under its own weight.

*(drawing: Scientists drill ice cores that hold frozen air bubbles from as far back as 800,000 years ago.)*

**Example.** In the mountains of Norway, a thick glacier once pushed through a narrow valley for thousands of years. Its weight scraped away rock on both sides, carving the valley into a deep U shape instead of the narrow V shape a river would leave. As it crept forward, the glacier also dragged along piles of broken rock and dirt. When the ice finally melted back, it left those piles behind in ridges called moraines.

*(drawing: Together, the Greenland and Antarctic ice sheets hold enough ice to raise sea levels by more than 65 meters.)*

**Tip.** A glacier does not slide like an ice cube on a table. It flows more like thick honey, bending and stretching as gravity pulls it downhill, just too slowly for your eyes to catch.

**Recap.** Snow compresses into glacier ice that flows and carves the land, while the huge ice sheets of Greenland and Antarctica lock away both sea level and 800,000 years of climate history.

## 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)