Sand Analysis Lab

Original images of the Cove have been lost. This beach is the best representation.

Charley Young

The Cove

Charley Young

Introduction: A beach is a location where a sediment is actively being exchanged through tidal movements. This sediment can be any number of types of sediment, but it is usually called sand. Sand can be classified as either biogenic (produced by living creatures) or detrital (produced by nonliving objects eroded down (detritus)). The purpose of this lab is to select several Maui beaches and determine whether the sand there is biogenic or detrital. Most of the biogenic material comes from coral. Coral is built from calcium carbonate. When calcium carbonate comes into contact with acetic acid (vinegar), it produces calcium acetate, water, and carbon dioxide. You can hear the carbon dioxide being produced; it creates a crackling noise.

Question: Which beaches on Maui have detrital sand, and which ones are biogenic?

Hypothesis: I believe that the Cove and Charley Younge both have mostly biogenic sand. If the sand is biogenic, it will chemically react with vinegar.

Materials:

• Cups


• Some form of transportation


• Tape


• Markers


• Two beaches (The Cove and Charley Younge in this case)


• Beakers


• Pipettes


• Vinegar

Procedure:

1. Collect samples. Place in labled cups.


2. Place sand in beakers. The sand should just cover the bottom of the beaker.


3. Using a pipette, drop one milliliter of vinegar into the beaker with the sand.


4. Check for a reaction. Sometimes the reaction will be visible but if not, place ear over the opennig of the beaker to hear for the crakling.


5. Record results.

Data: The Cove had a large amount of rock availible, but most was placed by people, and thus had little time to erode. I suspect that very little sand will be detrital. Charley Young may have some natural rock formations, but the sand is still a pale color which indicates that much of it is ground coral and thus biogenic. Both sand samples reacted when they came into contact with the acetic acid.

Conclusion: During this lab, we asked ourselves which beaches were biogenic and which were detrital. I suspected that the Cove and Charley Young were both mostly biogenic, and that if this were the case, they would react with acetic acid. Because both samples reacted with the acetic acid, both samples must have contained biogenic material.

Sources of Error: The sand may not have been representative of the beach, though this is unlikely. Variations in the amount of acetic acid introduced to the sand, and the sand itself may have altered the reaction. Our test was not specific enough to tell how much of the sand was biogenic, so even the mostly detrital beaches reacted because they still contained some of the calcium carbonate.