Geology is all around us. Depending on where we live, we have examples of mountains eroded away by wind and rain, the coastline under constant attack of waves, mountain streams that carry sediment from the tops of mountains to the lakes and rivers below.
Elementary school children are taking notice of the world around them and love to interact with it while they ask “how” and “why”. Kids love to play with sand, water, and rocks. What better way to introduce them to the science of geology. These geology experiments can be done at home or in the classroom using simple materials available around the house.
Our coastal shorelines are constantly under attack by the waves of the ocean. In this experiment, you will see how the earth is being worn away, eroded, and how the process of erosion constantly changes the shape of the earth’s surface.
For this experiment, you will need a metal baking pan, some sand or very fine soil and water. Pile the sand at one end of the baking pan and firmly pat it down. This will represent the beach or shore. Pour some water into the middle of the pan until part of the shore is slightly covered. At first gently, then increasingly faster, move the pan back and forth. Small waves will roll up onto the shore. Watch as the sand shifts and moves and washes into the water.
The action of the waves in the container gradually moves the sand down the beach and into the water. This gradual action of water against the land is called erosion.
This is an outdoor project. Take some sand and make a small hill using your hands to pat it down hard. Use a spade or other tool to make a creek that meanders down the side of the hill. In places where the creek curves, add some softer sand. Add some pebbles as “boulders” along the edges of the creek.
Take a watering can and water the top of the hill. Watch how the water from the “rain” flows down the creek. What happens at the curves and boulders? Create a harder rain by pouring water out of the can faster. Notice the effects of erosion on your mountain.
For this experiment, you will need three glass jars with lids. Fill each jar full of soil collected from different locations and depths. Add water, screw the lid on tight and shake well. Set the jar down and don’t disturb it.
Keep checking the jar several times during the day until the water is clear. This will take at least two hours. You can sit and watch it if you want but you don’t have to.
When it’s done, notice how the layers of different colors and sizes of material. Inspect the layers of soil with a magnifying glass if you have one. What you see is sort of like the natural materials that settle on the ocean floor, a new layer each year. They lay there, one on top of the other, undisturbed for thousands of years.
How do you think nature decides which materials to settle on the bottom and which ones will be on top? What happened to the shell and the dead bugs? Are they on the bottom?
MORE ABOUT SEDIMENT
Looking at your jars of sediment, consider how, over time, layers of sediment deposited by water, wind, or rain are pressed into rock by the weight of the sediment layers or water above them. This is called sedimentary rock’.
To demonstrate the way many layers of sediment increase the weight on the layers below them, lay your hand flat on the table. Set a book on top of your hand. Think of this as one layer of sediment. Then stack a second book on top of the first one. Now there are two layers of sediment and you probably feel the weight pressing down on your hand. You can add as many books or layers of sediment that you want until it becomes uncomfortable. Each book causes more pressure or weight on your hand, just like the bottom layers of sediment. Eventually, the sediment will turn into rock from the pressure (weight) pressing down over time.
If you have flagstone on your patio, this is an example of sedimentary rock. Shale is another example of sedimentary rock. When small pieces break off, they come off in flakes, showing the different layers of sediment.
Children love to play with sand and water, and some adults, too. Enjoy these simple projects with your children to help them learn how wind and rain work with the rocks and soil to create the landscape we see every day.
An excellent Internet resource with pictures and stories from around the world is geology.com. Kids and adults will enjoy learning about everything from the mysterious Sliding Rocks of Racetrack Playa to the Grand Canyon.