For Kids: Activities
Volcanic Eruption
Make a volcanic lava eruption and learn about lava layering.
Have your parents help you.
Materials:
- Paper cups, 4 oz size, some cut down to a height of 2.5 cm
- Cafeteria tray or cookie sheet, 1 for each eruption source
- Tape
- Tablespoon of Baking soda
- Measuring cup
- Vinegar
- Food coloring, 4 colors; for example: red, yellow, blue, green
- Playdough or clay in the same 4 colors as the food coloring (recipe for
playdough is below if you want to make it.)
Procedure:
- Take one paper cup that has been cut to a height of 2.5 cm and
secure it onto the tray. (You may use a small loop of tape on the
outside bottom of the cup.) This short cup is your eruption source
and the tray is the original land surface.
- Place one Tablespoon of baking soda in this cup.
- Fill 4 tall paper cups each with 1/8 cup of vinegar.
- To each paper cup of vinegar add 3 drops of food coloring; make each
cup a different color. Set them aside.
- Set aside small balls of playdough one of each color. (There is a recipe
to make playdough below. Get your parents to help you!)
- You are now ready to create an eruption. Pour red-colored vinegar into
your source cup and watch the eruption of "lava."
- As best you can, use red playdough to cover the areas where red "lava" flowed.
- Repeat steps 6 and 7 for each color of vinegar and playdough. You may
add fresh baking soda to the source cup or spoon out excess vinegar from
the source cup as needed.
- Answer the questions below by looking at your model and reading "The
Moon's Lava Layering More Information" below.
Lava Layering
Results:
- After your four eruptions, can you still see the original land
surface (tray)? Where?
- Describe what you see and include observations of flows covering or overlapping
other flows. Make a sketch, of what you see.
- Where is the oldest flow?
- Where is the youngest flow?
- Did the flows always follow the same path? (Be specific)
- What do you think influences the path direction of lava flows?
- If you had not watched the eruptions, how would you know that there are
many different layers of lava? Give at least 2 reasons:
- What of the reasons listed in answer 7 could be used to identify real
lava layers on Earth?
- What are other ways to distinguish between older and younger layered
lava flows on Earth?
- Which of the reasons listed in answer 9 could be used to identify lava
layers on the Moon?
- What are other ways to distinguish between older and younger layered
lava flows on the Moon?
- Make a vertical cut through an area of overlapping playdough "lava" layers.
Draw what you see in the vertical section. Color your sketch and add these
labels: Oldest Flow, Youngest Flow.
Playdough for Lava Layering
Preparation:
Baking soda-vinegar solutions and playdough are used to model the basaltic
lavas. Different colors identify different eruption events; this activity
calls for 4 colors. You will be asked to observe where the flows traveled
and to interpret the stratigraphy. Cover the work area and be prepared for
spills
Playdough (stove-top recipe)
Best texture and lasts for months when refrigerated in an air tight container.
- 2 cups flour
- 1/3 cup oil, scant
- 1 cup salt
- 2 cups cold water
- 4 teaspoons cream of tarter
- food colorings (20 drops more or less)
Make this large batch one color or divide ingredients in half to make 2
colors. You will need 4 colors total. Combine ingredients and cook mixture
in a large sauce pan, stirring constantly, until the dough forms a ball.
Turn dough out onto a floured surface to cool. Then kneed until smooth and
elastic. Cool completely; refrigerate in air tight containers.
Playdough (no-cooking recipe)
- 2 cups flour
- 2 tablespoons oil
- 1 cup salt
- 1 cup cold water
- 6 teaspoons alum or cream of tarter food coloring (as above)
Make this large batch one color or divide ingredients in half to make 2
colors. You will need 4 colors total. Mix ingredients and kneed until smooth
and elastic. Store in air tight containers.
The Moon's Lava Layering
Dark, flat maria (layers of basaltic lava flows) cover about 16 percent
of the Moon's total surface. They are easily seen on a full Moon with the
naked eye on clear nights from most backyards. The maria, quite similar to
Earth's basalts, generally flowed long distances ultimately flooding low-
lying areas such as impact basins. Yet, the eruption sources for most of
the lunar lava flows are difficult to identify. The difficulty in finding
source areas results from burial by younger flows and/or erosion from meteoritic
bombardment.
Generally, the overall slope of the surface, local topographic relief (small
cliffs and depressions), and eruption direction influence the path of lava
flows. Detailed maps of the geology of the Moon from photographs reveal areas
of complicated lava layering. The study of rock layering is called stratigraphy.
On the Moon, older flows become covered by younger flows and/or become more
pocked with impact craters.
On Earth, older lava flows tend to be more weathered (broken) and may have
more vegetation than younger flows. Field geologists use difference in roughness,
color, and chemistry to further differentiate between lava flows. They also
follow the flow margins, channels, and levees to try to trace lava flows
back to the source area.
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