Science Fenns K-5Grades K to 5
A split picture of a river delta fanning into a bay on the left and a deep layered canyon on the right.

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Deltas and Canyons

Water builds and carves.

Lesson 30 of 41

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Before we start

Today’s story

Deltas and Canyons

A creek after a Texas thunderstorm runs brown. It carries sand and mud. Where it meets a pond or the sea, the water slows down. The sediment drops. Over many years it builds up into new land.

That new land often spreads out like a fan. It is called a delta. The Mississippi River has a famous delta. Water does the opposite work too. A fast river cuts down into rock, bit by bit, and makes a canyon.

Palo Duro Canyon in the Texas Panhandle was carved by a small river over a very long time. Water builds and water carves. Here are the steps.

See it

Five steps. Every time.

    Hands on

    Stream Table

    30 minutes · Do this with a grown-up nearby

    You need

    • a baking pan or plastic tub
    • damp sand
    • a cup
    • a small paper cup with a pinhole
    • water
    • a book to tilt the pan

    Do this

    1. Pack damp sand into one end of the pan.
    2. Prop that end up with the book so it slopes.
    3. Pour water slowly from the high end.
    4. Watch where the water cuts channels.
    5. Look at where the sand piles up at the low end.
    6. Pour again, faster, and compare.
    Write or draw: Draw the pan after each pour. Mark where sand was removed and where it was dropped.

    Watch for: A channel is cut at the top. A fan of sand grows where the water slows. That is a mini delta.

    Safety: Work over a tray or outside. Wipe up spills so no one slips.

    Same every time

    Three rules

    Rule 1Fast water carves.

    Slow water builds.

    Rule 2Both take a long time.

    But a big flood can change land fast.

    Rule 3Landforms are made by erosion and deposition.

    They work together.

    Grandpa Fenn’s notebook

    Say it like a scientist

    delta
    New land built where a river drops sediment at its mouth.
    canyon
    A deep, steep valley cut by flowing water.
    channel
    The path a stream cuts as it flows.
    erosion
    Wind or water moving rock and soil from place to place.

    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 a canyon was carved by water?
    • Is there a creek or ditch near your home with a bend or a bank that has worn away?
    Did you know

    The Grand Canyon is about 277 miles long and the Colorado River carved it over millions of years.

    Someone who does this

    A civil engineer designs bridges, levees and channels that work with moving water.

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