Activity 3
Volcanic Rocks
A laboratory investigation
Your mission is to describe 4 unlabelled volcanic rocks and identify
the processes that formed them.
Materials you need
✓ 1 volanic rock set [consists of at least one piece of obsidian,
conglomerate, tuff, and basalt]
✓ 4 rock observation sheets
✓ 1 volcanic rock reference chart
✓ 1 volcano chart [from Activity 1]
✓ 1 set of research notes [from Activity 2]
Procedure
Complete an observation sheet for each rock [be as descriptive as
possible].
Identify the volcanic processes that formed each rock, using information from your volcano chart [Activity 1] and your notes from the
class research projects [Activity 2].
Complete the rock identification chart
Complete column 5 [rocks] in the volcano chart from Activity 1.
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observation sheet number __________________
To be filled out for each rock
rock name
Rock name:
[If you don’t know the name, skip this part and return to it later]
color
Color:
texture
Texture:
What does the feel like? Sharp, sticky, smooth? Use lots of adjectives.
grain size
Grain size:
How big are the particles in your rock? What is their general shape?
homogeneity
Homogeneity:
Is the rock uniform? [In other words, does the rock contain many
different parts or does it all look the same?)]
If the rock is not homogeneous describe how each part is different
(size, color, shape, abundance).
descriptions
Descriptions and Sketches:
Write a sentence describing the rock so that someone who hasn’t
seen the rock before could find it in a pile of other rocks.
Draw a sketch or your rock including all the features you can see
- look hard.
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questions
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Based on your observations and your knowledge of volcanic processes
answer the following questions:
1.
Does this rock have bubbles or holes in it? If yes how could
they have formed?
2.
Does this rock look like dried lava? If yes, why?
3.
Was this rock formed by water? Explain your answer.
4.
Does this rock look like glass? What kind of volcanic product
would have produced it?
5.
Was this rock once ash? How do you know?
6.
Is this rock heavy or light? What does this tell you?
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volcanic rock reference chart
Complete the following reference chart using the rock observation
sheets. Use your own words to describe the rocks and the processes
that formed them. You’ll be using this chart for the A-Mountain field
investigation, so be as descriptive as possible!
Description
Volcanic process
Tuff
Basalt
Obsidian
Conglomerate
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