Science Fenns K-5Grades K to 5
Rolling sand dunes in West Texas with wavy ripples on their slopes and a few hardy grasses.

Science / All lessons / Water, Rock and Landforms

Sand Dunes

Wind piles up the land.

Lesson 31 of 41

Try this first

Before we start

Today’s story

Sand Dunes

Out in West Texas near Monahans there are hills of pale sand. They are sand dunes. Wind built them. There is no river there. There is only sand, wind and time.

Wind lifts loose, dry sand and carries it along. When the wind slows or hits something, the sand falls out. Grains pile up in a heap on the downwind side. The heap grows, and a dune is born.

Dunes also move. Sand blows up the gentle slope and tumbles down the steep side. Slowly the whole dune creeps along. Plants can hold the sand in place. Here are the steps.

See it

Five steps. Every time.

    Hands on

    Wind-Made Dune

    25 minutes · Do this with a grown-up nearby

    You need

    • a shallow box or tray
    • dry sand or fine salt
    • a small block or rock
    • a hair dryer on low or a paper fan
    • a ruler
    • safety glasses

    Do this

    1. Spread dry sand across the box.
    2. Set the block near one end.
    3. Wear glasses and use the fan or a dryer on low.
    4. Blow gently across the sand toward the block.
    5. Watch where the sand piles up.
    6. Measure the pile height with the ruler.
    Write or draw: Draw the box from above and from the side. Show the wind direction with an arrow.

    Watch for: Sand piles up on the far side of the block, not the near side. The pile has a gentle slope facing the wind and a steep slope on the far side.

    Safety: Wear safety glasses. Use a paper fan, or ask an adult to run the hair dryer on low and keep it away from water.

    Same every time

    Three rules

    Rule 1Wind moves only dry, loose sand.

    Wet sand stays put.

    Rule 2Dunes grow downwind of an obstacle.

    The obstacle slows the wind.

    Rule 3Plants can hold dunes in place.

    Roots grab the sand.

    Grandpa Fenn’s notebook

    Say it like a scientist

    dune
    A hill of sand built by the wind.
    deposition
    When wind or water drops what it carries.
    erosion
    Wind or water moving bits of rock and soil away.
    obstacle
    Something that gets in the way and slows the wind.

    Poppy’s quiz

    Six questions

    Tap an answer. Green means right. You will see why.

    Talk about it

    Say it out loud

    • What evidence shows that wind, not water, made a dune?
    • Where have you seen blown sand or dust near home, like along a fence or a road?
    Did you know

    Some dunes in the world are over 1,000 feet tall, and they can sing, making a low hum when sand slides.

    Someone who does this

    A park ranger protects natural places and teaches visitors about them.

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