What the Ice Left Behind
Ice does not flow around obstacles the way water does, so glaciers gouge straight, steep-sided valleys and dump unsorted rubble where they stop. Much of northern Europe and North America is still wearing the shape of ice that melted ten thousand years ago.
What a learner can do afterwards
- Say how a glacial valley differs in cross-section from a river valley, and why
- Name two things a glacier leaves behind when it melts
- Explain why lakes are common in landscapes that were once under ice
1 · Read
Ice does not flow around obstacles the way water does. A glacier is a thick, stiff mass that grinds the whole valley floor and walls as it moves. So it gouges a wide valley with steep sides and a flat floor, shaped like the letter U.
A river cuts a thin channel and leaves a narrow valley shaped like the letter V. Stand the two side by side in your mind. U means ice did the work, V means running water did.
When the ice melts, it drops everything it carried. It leaves ridges of dumped stones and clay called moraine, scratched bedrock, and boulders parked in odd places. It also leaves scooped hollows that meltwater fills, which is why chains of lakes dot lands the ice once covered.
To read a landscape, hunt the clues together. A U valley plus scratches plus dumped ridges plus lakes spells glacier. Much of northern Europe and North America still wears that shape from ice that melted ten thousand years ago.
Stiff ice gouges wide U valleys and dumps rubble and lakes, while rivers cut narrow V valleys.
2 · Watch
Take it off screen
Where it sits
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.