Why Do Dunes Slowly Move Across the Land?

What Crafty Clover says in this video

Intro

Hi there, curious minds! I'm Crafty Clover! Let's discover something amazing. Why do dunes slowly move across the land?

The Big Idea

Dunes move because the wind blows grains up the gentle side, over the top, and down the steep slip face! Grain by grain, the back edge is eaten away and the front edge builds up. So the whole hill creeps forward.

Up and Over

Step one: up and over. Wind blows sand grains up the gentle back of the dune. Then they tumble over the crest, one layer at a time.

Back Shrinks, Front Grows

Step two: the back shrinks and the front grows. Sand leaves the back edge and piles up on the front edge. That means the whole dune slowly slides forward.

Fast or Slow

Step three: some dunes move faster than others. Small dunes can move many feet in a year, while huge dunes move far more slowly. Some dunes stay mostly in place because plants hold them down.

A Closer Look

Let's take a closer look! The wind blows in one main direction. It carries grains up the gentle side. They slide down the steep side. And so the dune moves ahead. It is like a very slow wave of sand.

Quick Facts

Quick facts! Small dunes can move many feet in one year. Giant dunes move much more slowly. Plants can hold dunes in place with their roots. People sometimes plant grasses to keep sand from covering roads.

Think Like a Scientist

Now, think like a scientist! Draw a dune as a triangle in your notebook. Add arrows for the wind and the sliding sand. Then draw it again as it would look a year later, shifted to the right. Show a grown-up your drawings.

Outro

Dunes creep forward as the wind moves sand from back to front. Science is amazing! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!