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Ice Ages & the Power of Glaciers
How can ice reshape an entire continent?

Glaciers are Earth's sculptors! In this lesson, your learner will discover how Ice Ages happened not just once but many times, and how massive glaciers carved out valleys, moved boulders, and literally reshaped the continents. They'll learn about land bridges that appeared and disappeared, allowing animals and humans to migrate across the world. It's a powerful reminder of how dynamic our planet is and how frozen water can transform entire landscapes.

S2S_Lesson27 by Selene

Key Ideas

  • Repeated Ice Ages reshaped continents through erosion, deposition, and sea-level change.
  • Glaciers carved valleys, moved rocks, and altered ecosystems.
  • Lower sea levels exposed land bridges such as Beringia, connecting continents.
  • These changes influenced animal movement, human migration, and long-term ecological patterns.

Spines
  • DK's Science as You've Never Seen it Before: Climate Change pg. 128-129
  • Mammoth Science: Climate pg. 146, Seasons pg. 144
✏️  Notebooking Activity
Draw a simple diagram showing a glacier moving across land. Label what happens: rock being pushed, valleys being carved, sediment being deposited.


Cosmic CalendarWhere we are: December 31 · Late evening*
We are deep into the evening of December 31st. This date is a reasoned estimate. Read the script below before the lesson.

Read aloud: Still December 31st on our Cosmic Calendar, and we’re getting into the late evening hours now. The most recent Ice Age peaked around 20,000 years ago. On our calendar, that’s only about a minute and a half before midnight. Glaciers covered large parts of North America, Europe, and Asia. Sea levels were much lower than they are today. We are so close to the end of the calendar that we’re no longer talking about days. We’re talking about minutes and seconds. Everything from here until midnight on December 31st is the story of us.
Timeline EntriesLabel the next page in your timeline “Ice Ages & The Power of Glaciers: 115,000 Years Ago”. The workbook prompt asks learners to draw a massive glacier pushing across a landscape, scraping boulders, carving a valley, and leaving a moraine ridge of rocks and gravel at its edge.

Discussion Questions
  1. What is a glacier? 
    Sample answer: A giant sheet of ice that moves very slowly.
  2. What happens to land when ice moves over it? 
    Sample answer: The ice can scrape, push, and change the land.
  3. How do glaciers physically reshape the land? 
    Sample answer: Glaciers erode rock, carve valleys, and deposit sediment as they move.
  4. Why do land bridges form during Ice Ages? 
    Sample answer: Water is locked in ice, lowering sea levels and exposing land.

Digging Deeper
  • Why are Ice Ages important to human history? 
    Sample answer: Ice Age conditions shaped migration routes, resources, and where people could live.

Vocabulary
  • Ice Age — A period of long-term global cooling during which ice sheets expand across large parts of Earth's surface.
  • Glacier — A large, slow-moving mass of ice formed from compacted snow; glaciers carve valleys and move enormous rocks.
  • Erosion — The wearing away of land by wind, water, ice, or other forces; glaciers are powerful agents of erosion.
  • Land Bridge — A strip of dry land connecting two landmasses, exposed when sea levels drop due to water being locked in glaciers.
  • Beringia — The land bridge between Asia and North America (now under the Bering Sea) that allowed humans and animals to migrate.
  • Moraine — A ridge of rocks, soil, and sediment deposited at the edges or end of a glacier as it moves and melts.
  • Sea Level — The average level of the ocean surface; drops during Ice Ages and rises as glaciers melt.

SCIENTIST SPOTLIGHT: Lonnie ThompsonLonnie Thompson is an American glaciologist at Ohio State University who has spent his career drilling ice cores from glaciers in the tropics, places like the Andes, the Himalayas, and Mount Kilimanjaro, that most scientists assumed would not yield useful climate records. He was wrong to be doubted. The ice cores he and his team have retrieved contain some of the most detailed records of past climate available anywhere on Earth, stretching back hundreds of thousands of years. Thompson has also been one of the most consistent scientific voices documenting how rapidly these glaciers are disappearing. He has personally witnessed ice fields he first studied in the 1970s shrink dramatically, and he continues to collect cores from glaciers before they vanish entirely.

Videos:
Icy Warning from the World's Highest Mountains | Lonnie Thompson | TEDxOhioStateUniversity
Lonnie Thompson - “Canary” & Letting Glaciers Tell Their Story | The Daily Show

Digging Deeper Activity:
What is an ice core and what kind of information can scientists read from it? Research how scientists identify past volcanic eruptions, temperature changes, and even ancient air bubbles in ice core samples. What do Thompson’s tropical ice cores tell us about climate that polar ice cores cannot?

Species to ResearchThis lesson focuses on glaciers and Ice Age geography. Here are some animals from Ice Age ecosystems learners can choose to research:
  • Bison priscus (Steppe Bison)— A massive bison that roamed the cold grasslands of Ice Age Europe and Asia; its images appear in cave paintings.
  • Mammut americanum (American Mastodon)— A North American relative of the mammoth that lived in forests and browsed on shrubs; it crossed Beringia during low sea levels.
  • Megaloceros giganteus (Irish Elk)— A giant deer with antlers spanning up to 3.7 meters; one of the largest deer that ever lived.
  • Equus ferus (Wild Horse)— The Ice Age ancestor of modern horses; wild horses crossed land bridges and spread across multiple continents.

Sources and More Information:

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