Name ____________________________________________
What Stories Do Rocks Tell? (ES 2903)
Background
 using relative dating principles, the sequence of geologic events that occurred at a site can be
deduced.
 In an undeformed sequence of sedimentary rocks, the oldest rocks are at the bottom.
 Intrusions and faults are younger than the rocks they cut.
 Tilted, folded, or faulted layers of sediments were originally horizontal.
You will examine photographs and drawings, both line and block, of rock sequences. You will use a series
of animations to explore geologic processes and interpret the relative ages of the rock layers. You will
also observe deposition of layers, faulting and folding of layers, and the combined processes that result
in an unconformity. At the end of the investigation, you will be presented with a new site to interpret.
You will number the rock layers from oldest to youngest and write a detailed description of geologic
history of the site.
Some things to keep in mind about this investigation: the Colorado Plateau in the southwestern United
States is a geologically rich area of the country. Many national parks, including Bryce, Canyonlands,
Arches, Zion, and the Grand Canyon, are located in this region.
Conclusions
1. Identify at least three geologic processes represented in the images.
2. What evidence might indicate that these processes also have occurred sometime in the past?
3. Which layers were deposited first and are therefore the oldest?
I hereby declare upon my word of honor that I have neither given nor received any unauthorized aid on
this work.
______________________________________________________
Name ____________________________________________
2013
4. Which layers were deposited last and are therefore the youngest?
5. How might layers that were once horizontal come to be tilted like this?
6. What type of force was applied to these rocks to form folds?
7. Identify and label the unconformity on your diagram. Number the layers from oldest to
youngest. 1 = oldest, and 7 = youngest.
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Name ____________________________________________
2013
8. Make a sketch of the layers on the front of the 3-D block. Then, number the layers from oldest
to youngest.
9. Now write a detailed description of the geologic history of the site you just sketched.
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