Sand Origins

There are two different origins of sand; biogenic and detrital. The chemical reaction between vinegar and sand determines the type of sand. If the sand bubbles when vinegar is added it is biogenic, if it does not bubble when vinegar is added then it is detrital. In this lab we will test different samples of sand with vinegar to determine the origin.

(Big Beach)

Question: Which beaches in south Maui will prove to be biogenic or detrital?
Hypothesis: I hypothesize that Big Beach will be biogenic because of the large amount of reef off of the shoreline and that Black Sand Beach will be detrital because of the many cliffs surrounding it. If Big Beach is biogenic then the sand will bubble when we add vinegar. If Black Sand Beach is detrital it will not bubble when we add vinegar.

Materials: Papette, pencil, sand, vinegar, container, notebook
Procedure:
1. Collect sand from chosen beaches and make observations of the beach surroundings in your journal
2. Gather remaining materials
3. Using the papette add vinegar to the sand
4. Observe any possible chemical reactions
5. Note chemical reactions and use the following formula to determine the origin of the sand
6. 2CH3COOH + CaCO3 ----> Ca(CH3COO)2 + H2O + CO2

(Black Sand Beach)

Data:

Field Observations- As part of class on monday, April 11, we headed outside to collect sand samples. I took samples, pictures and observation of the following beaches.

At Keawakapu I observed lava rocks on both ends of the beach and the sand was more a white/tan color.

At Kamaole 1 I observed rocks off of each end of the beach. Signs to protect coral reef suggests that there is a large amount of coral off shore. There was also sand dunes acting as protective barriers from the street.

At Sugar Beach I observed a lot of rocks and the sand was darker than the other sand samples. I also noticed that the water was very murky and I'm not sure what that means, but it might be an indication of animal and water activity which is related to the sand.

Sand Analysis- During class on wednesday, April 13, we tested the sand samples that we collected from various beaches.

The sand from Black Sand Beach, which was dark colored, proved to be mostly detrital because there was a very minimal reaction to the vinegar. The sand from Big Beach, which was a light tan color and more thick than fine, proved to be mostly biogenic because there was a noticeable reaction to the vinegar.

(Photo was taken at Black Sand Beach in Maui, HI. The beach is known

for its dark sand and cliffs surround the left end of the beach.)

Conclusion:

     Which beaches in south Maui will prove to be biogenic or detrital? I hypothesize that Big Beach will be biogenic because of the large amount of reef off of the shoreline and that Black Sand Beach will be detrital because of the many cliffs surrounding it. My hypothesis proved to be correct because the sand sample from Big Beach had a reaction to the vinegar, whereas the sand sample from Black Beach had a very minimal reaction. Possible sources of error; sand type varies due to location on the beach, not thoroughly observing the reactions, misreading the sand sample cups lable, being tired because it was early in the morning, not enough vinegar was used, etc.

(Photo was taken at Big Beach in Maui, HI. The picture shows the beach

area as well as the cliff that separates Big Beach from Little Beach.)