Hands-On Assignment: A Grain of Sand

Worth Twenty (20) points.

Due 1159PM, Monday, April 1, 2002

Name __________________________ Section __________ Date __________

Materials

For this exercise, you will need:

• three sample bottles at least 500 milliLiters (mLs) each
• newspaper
• blank white index cards
• Elmer's glue
• a screen or screens made from a colander with fine mesh or similar
• a magnifying glass

Methods

1. Find a beach on the ocean where beach sand is present. Deserts, rivers and lakes will not suffice for this exercise. Believe me, I'll know the difference!

2. Collect three samples of sand from three different locations that are different distances from the waterline. Ideally, you should collect one sample above the berm, one sample on or near the berm and one sample as close to the water as possible. You should collect at least 500 ml from each of the three locations. Empty water bottles make ideal sample containers. Make sure you label each container according to its location, i.e., above the berm, at the berm, below the berm.

3. Take the samples home and spread them out on a newspaper. Let them dry 2-5 days, the dryer the better.

4. Take a blank index card (white non-ruled is best) and dab a small amount of white Elmer's glue onto the card. Sprinkle a small amount of sand from one location onto the card. Label the card. Repeat this procedure for each sample. You will turn in your three sample cards with the assignment so keep them in a safe place when you are finished describing them (see below).

5. Around the house, find some type of screen or some object with regular and similarly shaped holes in it. A window screen (one that you aren't using), a coffee screen, a colander, a mesh paper clip holder, even the plastic screen from the front of your boom box will work. If you must, make a screen from a plastic lid; just make sure the mesh size (the size of the holes) is the same. If you can find two screen-type objects with different mesh sizes, even better. Now, measure out two (2) cups of sand from one of your samples. Carefully pour the sand through the screen. Gently shake the screen to separate the grains of sand. You may want to pour just a little through the screen at a time until you have poured the entire two (2) cups through the screen and completely separated the sample.

The idea here is to separate large grains from small grains. If all the sand goes through your screen, find a smaller screen. Once you have separated your sand into two (or three) size categories, measure the amount of sand in each category. Record the amount (in cups) for each sample, according to its location and size class, i.e, small, medium or large (or just small and large, if you only used one screen). Repeat this procedure for each sample.

Results

1. Make a table of data that looks like the table below. Your amounts will vary from the amounts below. They should add up to two (2) cups (or very close). Calculate the percentage of each size fraction by dividing the amount (trapped or going through) by the total (2 cups). and include it in the table. Also, be sure to label your table with a proper legend, i.e., Table 1: Sand samples collected at three different locations--above berm, at berm and below berm--from Huntington Beach on March 25, 2002.

 Sample Amount trapped above screen Percentage Amount going through screen Percentage A (above berm) 1 cups 50% 1 cups 50% B (at berm) 1.5 cup 75% 0.5 cup 25% C (below berm) 0.5 cups 25% 1.5 cups 75%

Table 1: Sand samples collected at three different locations--above berm, at berm and below berm--from Huntington Beach on March 25, 2002.

2. Graph your data using a pie chart or column chart in a spreadsheet program or by hand. Go to http://www.oceansonline.com/sicc_sandgrainsf299.htm or http://www.oceansonline.com/sicc_sandf199.htm and see how those students did it for more complex sand grain size analyses.

3. Take a hand lens, magnifying glass, someone's glasses or something that magnifies and describe the following for each sample. Remember, you have three samples:

• color(s) of the individual sand particles (i.e., black, yellow, pink, tan, brown, caramel, buttercup, etc.)
• approximate percentage of the each color (mostly yellow, few silver particles, etc.)
• the shape of the individual sand particles (round, spherical, oblong, square, etc)
• the angularity of the particles (very angular, angular and smooth edges, very smooth, etc.)
• any other distinguishing features or observations (bits of shells, bits of seaweeds, pieces of a crab, etc.)

Write these observations into the form of another table. Label this Table 2 and add a legend, i.e., Table 2: Observations of sand samples taken at...etc., etc.

Discussion

Answer the following questions on a separate sheet of paper using the data you collected and graphed above.

1. What is the range of percentages for each sample? (Hint: Refer to your table. Give the lowest and highest percentages that you observed for each of the three locations. For example, in the table above, Sample B ranged from 25% for the large grain size to 75% for the small grain size.)
2. How do the percentages vary between the three locations? How are they similar?
3. How do the observations of color, shape and angularity differ between the three locations? How are they similar?
4. In 250 words or so, describe the processes on the beach that account for the differences in sand grain size and composition (color, shape and angularity) between the three locations. Be sure to mention longshore current, wave energy, tides and other processes that control the size and shape of sand on the beach.