Coastal Investigation of Sand using the SandSnap Database

Coastlines are dynamic areas that are vulnerable to erosion from waves and flooding from storms and sea level rise. The coastal zone provides habitat for marine life and birds, food for people, recreational opportunities, and often supports high-density coastal communities. Science driven management decisions are needed to protect these areas. Effective policies need to be developed with the best understanding of the physical processes impacting the shoreline possible. This requires monitoring the physical processes, such as sea level rise, waves, and tides, that impact the shoreline as well as documenting the physical characteristics of the beach, such as the elevation, width, and sand size.

In this lesson, you will explore the clues sand provides about the processes impacting the shoreline.

After you complete this lesson, you will be able to …

1. Predict the direction of sediment transport based on sediment properties. ( investigation 1 )
2. Test your predictions using orthophotos. ( investigation 2 ) 
3. Develop an explanation for why sediment size varies by location and test the explanation with data.  ( investigation 3 )

Before you begin download a copy of the student handout or get a copy from your teacher.

Data for this lesson comes from the SandSnap database. SandSnap is a citizen science project created to develop a grain size database for scientists, engineers, local community leaders, and students! The data is collected by the public and stored in an online database. Anyone can contribute a sample by just submitting a photo of the sand. It is that easy. The image is analyzed with a machine learning algorithm and the results are shared within minutes. The results are permanently stored in the SandSnap database.

Not all sand is the same. It may vary by composition or size. Changes in composition can be recognized as color changes. Use the database to explore sediments all over the world. Record your observations on your field notes.

Hint: Need some help finding unique sediments- look at the sample from Kona Hawaii then look at a sample from Palm Coast Florida. Why do you think these samples are different?

Our beaches are covered with sand of many sizes and colors.  There are white, fine-grained, powdery beaches, coarse gravel beaches, and beaches made of broken shells.  Observations scientists make about sand can be used to learn more about the processes occurring along the coast.  The purpose of this investigation is to explore sand around the world to learn more about the coast.

The sand we see on the beach is a function of sediment source and modification of the sediment as it is transported.  Sediment is transported to the beach by rivers, waves, coastal currents, and wind.  As the sediment is transported the grains become smaller and more rounded, and the mineral content of the sand decreases as the easily weathered minerals are removed (fig 1).  These patterns can tell us something about the processes active along the coast.

The longshore current moves sand along the coast, parallel to the shoreline.  Identifying the direction of the longshore current can help resource managers make better land use decisions.  The longshore current can be measured with a current meter, but geoscientists can also use the sand as a clue to the transport direction.  As the sand is moved in the direction of longshore transport, the sediment will continue to weather.  As weathering processes continue, the sand will become finer, more rounded, and the mineralogy will become less diverse. 

Below are sediment samples from 3 locations- Cape Cod, MA, Long Island, NY, and New Jersey. Examine the samples from each site to determine the direction of longshore transport.

These samples are part of the Rob Holman collection (Coastal Imaging Lab, CEOAS, Oregon State University).  The images were downloaded from the SandSnap database. These samples are high quality and have a scale at the bottom of the photo. The scale helps when comparing different samples.

The next step is to validate the predictions you created in investigation 1. To validate the predictions, you will look for evidence of longshore transport in aerial photographs. As sand is transported along the beach

Return to the areas you studied in investigation 1. Can you find any evidence of longshore transport that supports or contradicts your initial prediction of longshore drift direction based on sediment characteristics? Use the map below to search for evidence. The bookmark button (2nd to the bottom on the left) will help you zoom into the different areas and the snapshot button (bottom button on the left) will take a picture to document your evidence. You can use the (+) to zoom in closer and the (-) to zoom out. You can copy and paste the image into your field notes.

Ashley, G.M., Halsey, S.D. & Buteux, C.B. 1986. New Jersey's longshore current pattern. Journal of Coastal Research, 2(4), 453-463. Fort Lauderdale, ISSN 0749-0208.

 Longshore Sediment Transport, Cape Cod, Massachusetts  by Greg Berman. 2011

Instructor Resources: For a PDF of teacher's resources please email Shelley Whitmeyer at whitm2 "at" jmu.edu.