The Volcano Station

 
 
Objective: to have the students create simple experimental models of miniature volcanic eruptions and to have them examine volcanic rocks. 

Supplies:  pictures of volcanic eruptions, 2 empty film cannisters with 1 lid, white vinegar with a drop or two of red food dye, baking soda, water, alkaseltzer tablets, 2 shallow mixing bowls,  newspapers, model volcano from paper mache, volcanic rocks (suggestions: obsidian, pahoehoe, aa, pumice and a bucket of water) 

To begin: Start with brief introductory discussion:  How many of you know what a volcano is?  Have you ever seen one erupting on TV?  Have you ever wondered what makes a volcano erupt?  Do you think that all volcanoes erupt the same way? (they don’t).  Let’s look at a picture of a volcano erupting on the island of Hawaii.  Do you know where Hawaii is?  Show them Hawaii on globe.  Point out that it is one of the states in the U.S. and it is completely made of volcanic rocks. 
Now look at a picture of a volcano erupting explosively.  It is Mt. St. Helens in Washington state. 

Experiments:   
There are two kinds of volcanic eruption: gentle and explosive.  Would they like to make their own miniature volcanic eruptions? 
Note: do “eruptions” in mixing bowls to minimize mess.  Red food dye can stain so newspapers underneath would also be a good idea.  If you have a model volcano (see attached recipe), you can do the eruptions in that. 

Effusive Volcanoes: put 1 tablespoon white vinegar with red food dye in a film cannister.  Add 1 tsp. baking powder.  Watch the volcano “erupt.” 

Point to make: This is an example of a volcanic eruption that flows.   

Explosive Volcanoes: fill film cannister 1/3 full of water, place 1 alka seltzer tablet in and put lid on firmly.  Tell everyone to back up.  Wait until it pops!   
Point to make: This is an example of an explosive volcanic eruption. 

Question: Which kind of volcanic eruption seems more dangerous? (exploding one)  
The proportions are not all that important.  You don’t have to clean up cannisters between experiments.   

Looking at volcanic rocks: In remaining time, show samples of obsidian, pyroclastic felsite, pahoehoe, aa and pumice.  Ask them to guess which rock floats.  Test their guess by taking them over to  bucket of water and dropping them in.  What happens?   (Pumice floats) Why does it float?  Trapped gas bubbles make it lighter than water. 

If kids are curious about why some eruptions are violent and others are gentle, you can try to create some discussion using the experiments as models.  When gas is free to escape it comes bubbling out and produces a gentle eruption, hurling hot lava up to a few thousand feet in the air.  That may seem like a lot, but its not much compared to a violent eruption such as Mt. St. Helens which erupted on west coast of U.S. about 15 years ago (they can ask their parents if they remember it).  That eruption hurled tiny bits of lava called ash so far into the atmosphere that a thin dusting of ash settled out even here in Dayton Ohio over a thousand miles away.  What causes a volcanic eruption to be so explosive?  When the gas is not as free to escape the gas pressure builds up and builds up until finally it explodes, like the build up of gases from the alka seltzer in the sealed film canister. 

Resources: 
Susanna van Rose, The Earth Atlas, Dorling Kindersley, 1994. 
Fiona Watt, Earthquakes and Volcanoes, in Usborne Publishing’s Understanding Geography Series. 

Literature Connection: 
Thomas Lewis, Hill of Fire, Harper and Row, 1971. 
Deborah Merrians, I Can Read About Earthquakes and Volcanoes, Troll, 1996. 
Virginia Nelson, The House on the Volcano, Scholastic, 1966. 

World Wide Websites: 
“Volcano World."  http://volcano.und.nodak.edu/   This site has lots of geology related material and links 
 

 
Please take me to... 
The Dinosaur Station
The Earthquake Station
The Fossil Station
The Minerals and Rocks Station
The Model of the Earth Station
The Plate Tectonics Station
The Volcano Station
The Water Cycle Station

 
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