Experiment: Build your own beach!

There is nothing better than spending a sunny day at the beach. There is always a lot to do. Build a sand castle, investigate tide pools and just relax. But have you ever wondered how the beach you are standing on came to be or if it will ever change? A beach is a geological formation made up of loose rock particles, such as sand, gravel and shell fragments, along the shoreline of a body of water.

There are a few key parts that make up a beach, as shown in Figure 1. The beach berm is the part that is mostly above water. This is the active shoreline. The top of the berm is known as the crest, and the part that slopes toward the water is called the face. At the bottom of the face, there may be a trough, and farther into the water there may be one or more sandbars parallel to the beach. At a point inland where the waves cannot reach, the wind takes over. The wind blows the sand into features beyond the crest. These features are known as dunes.

The erosion of rock formations in the water, coral reefs and headlands create rock particles that the waves move onshore, offshore and along the shore, creating the beach. Continual erosion of the shoreline by waves also changes the beach over time. When larger and stronger waves hit the shoreline, such as in a storm, more shoreline is eroded. One change that erosion can cause is the appearance of a headland. A headland is land, usually made of larger rocks, that juts out from the coastline and into the water. It affects how the surrounding shoreline erodes.

In this science project, you will make a model to investigate how water makes a beach and how a headland affects beach formation. Have fun, and remember to bring your sunscreen and icy soda to your handmade beach!

Terms and concepts

• Geological formation
• Shoreline
• Beach berm
• Crest
• Face
• Trough
• Sandbar
• Dune
• Erosion
• Headlands

Questions

• What are the different parts of a beach?
• What is erosion and how does it contribute to making a beach?
• What are dunes? What are some well-known dunes?

Bibliography

Have an adult help you do further research by visiting the following website, which gives information about shorelines and erosion:

• Minnesota Department of Natural Resources. (n.d.). Restore Your Shore. Retrieved June 26, 2012.

For help creating graphs, try this website:

• National Center for Education Statistics, (n.d.). Create a Graph. Retrieved June 25, 2020.

Materials and equipment

• Paint roller pan
• Dry measuring cup
• Sand (50-lb bag); clean beach sand can be purchased at your local hardware store.
• Water
• Plastic 500-mL water bottle
• Pencil
• Timer
• Digital camera
• Adult volunteer to help take pictures
• Ruler with millimeter markings
• Aquarium gravel (6 cups)
• Lab notebook

Experimental procedure

1. Cover the bottom of the paint roller pan with 5 cups (1.2 liters) of sand.

2. Build up a small beach with most, but not all, of the sand at the shallow end of the pan.

3. Slowly pour 6 cups of water into the deep end of the pan. Let the water and sand settle for five minutes.

• 3a. How has the beach changed during this time? Your beach should now look similar to Figure 2.

4. Take a picture of the beach so that you have a record of how it looked. Note where the shoreline is. The shoreline is where the beach and the water meet.

5. Make sure the plastic water bottle is empty and has its lid on. Lay the water bottle horizontally so it is floating in the deep end of the pan, along the beach.

6. Set the timer for one minute. Start the timer and then bob the water bottle up and down in the water with your fingertips to create waves.

• 6a. If the waves get so big that water splashes out of the pan, make the waves smaller.

7. At the end of one minute, stop bobbing the water bottle and take a picture of the beach. How does it look compared to the first picture? Write down your observations in a data table, like Table 1, in your lab notebook.

• 7a. In your data table, this beach type will be called “Without Headland.”
• 7b. After you are finished with the experiment, you can print out and put your pictures in your lab notebook, too. Be sure to keep track of which pictures match each step in the experiment.

8. Repeat steps 6–7 one more time for a total of two minutes of waves.

• 8a. Record your observations and take a picture to put in your lab notebook. How does your beach change with time?

9. Empty out, clean and dry your paint roller pan.

10. Repeat steps 1–9 two more times.

• 10a. Multiple trials help scientists make sure that their results are accurate and reproducible.
• 10b. Remember to record all of your observations in a data table like Table 1 in your lab notebook and to take pictures.

11. You will now use the gravel to model a headland. Repeat steps 1–3 and then make a mound out of 2 cups of aquarium gravel in the middle of the shoreline. The headland should be partly in the water and partly on the beach, as shown in Figure 3.

12. Repeat steps 4–9, but in step 7a, in your data table this beach type will be called “With Headland.”

13. Repeat steps 11–12 two more times.

• 13a. Remember to record all of your observations in your lab notebook in a data table like Table 1.

14. Review your observations and pictures. How does the beach change over time when it does not have a headland compared with when it does have a headland? How do the headlands affect where the water goes? Does the water swirl more at the sides? Did the distance between the shoreline and the edge of the roller pan change?

• 14a. Print out the pictures for your lab notebook to go along with all observations that you make.

Variations

• How do the waves erode the beach if you continue to make them for more than two minutes? Try this science project again but make waves for five, and then 10 additional minutes. How does the beach without the headland compare to the beach with the headland when waves are made for a longer amount of time?
• Either increase or decrease the speed of bobbing the water bottle up and down. Does this affect how the beach changes over time?
• Use a pencil to make smaller waves and see how this affects the shoreline.
• Tape a ruler to the side of the paint-roller pan and measure how the shoreline changes as a result of wave action. Measure from the shoreline to the end of the roller pan with the ruler every time you take a picture. How much did the distance change compared to the where the original shoreline was?
• Plot your data. Make two plots, one corresponding to the beach without the headland, and one for the beach with the headland. Label the x-axis Time and the y-axis Distance to the Shore.
  • If you need help making plots or would like to make them online, go to the following website: Create a Graph.
  • Print out the pictures of how your beach changed and the observations you made. Place all of the data on a display board so that you can show everyone how beaches are made.
• Pour a large volume of water all at once into the deep end to simulate a storm surge or tsunami. What happens to the beach?
• If you are interested in a science project about erosion, try Riprap: It’s Not Hip Hop But Erosion Stop.

This activity is brought to you in partnership with Science Buddies. Find the original activity on the Science Buddies website.