An interesting section of sedimentary
rock has been exposed by the Lehigh River. The river has carved out
a "window" that gives geologists an opportunity to examine
several different layers of bedrock. In this section you will examine
the ages and types of bedrock present
in the Lehigh Gorge.
The link below provides the stratigraphic column for rocks
in the Lehigh Gorge. Use the information found on the link below to
assist you with answering questions 1 and 2.
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1. What
are the names and ages of the bedrock
exposed in the Lehigh Gorge? List them in order of oldest to youngest
rock type.
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2. What symbols
represent each bedrock unit? How do the symbols represent the
age of the bedrock?
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All of the rocks in the Lehigh Gorge are sedimentary
and were formed millions of years ago. Examine the pictures on the
links below of each rock type and their descriptions. Note the similarities
and differences between the physical properties
of each rock type. Use the information found on the links below
to assist you with answering questions 3,4, and 5..
Stratigraphy
Hand Specimens
3. What type of rock
is predominant in the Pocono Formation? What are its characteristics?
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4. How would you describe the grain size
of the sandstone in the Mauch Chunk compared to that of
the Pocono Formation?
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| 5. How
many different rock types compose the Spechty Kopf
formation? How do you think this affects its ability to resist erosion?
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6. Which bedrock
unit does the Lehigh River erode through easily? What properties
of this bedrock unit make it "weaker" than the
others? Use the link below to assist you with this question.
Geologic
Map
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7. What depositional
environment would produce......
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conglomerate?
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sandstone?
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shale?
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mudstone?
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