AS MAPPING

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AS MAPPING
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You will be given a map which shows some simple
geological structures and features to interpret.
There will also be some questions which relate to
the map and to the rock, mineral and fossil
specimens.
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The map will have a key, a scale and a north
arrow.
4
The key will include the Rock Units shown on the
map. Sometimes you are told what type of rocks
each rock unit represents but not always. It is
a good idea to write the letters of each rock
unit on the map before you start using it.The
key also tells you which rock units have a
specimen available to study.
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Folds
What type of folds are these? What is the trend
and the symmetry of these folds?
A
B
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Folds
A
B
There are two folds on this map. What type of
folds are they? What is the trend and the
symmetry of these folds?
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Unconformities mark times when erosion is
dominant and no sediments are deposited. They
mark a break in deposition because of uplift and
mountain building. The rocks above overlay the
rocks below UNCONFORMABLY and are often very
different in dip and strike.
Unconformities cut across other beds.
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Folds
What type of fold is this? What is the trend and
the symmetry of this fold? Give the geological
history of this map.
D
C
B
A
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Unconformities
Locate a fold and an unconformity on this map.
Describe them both fully. Give the geological
history of this area.
A
B
C
D
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Unconformities
A
B
Where are the unconformities on these maps? How
can you be sure that they are unconformities?
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Unconformities
Locate two folds and an unconformity on this map.
Describe them both fully. Give the geological
history of this area.
D
A
B
C
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Locate a fold and an unconformity on this map.
Describe them both fully.
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Igneous intrusions
What type of igneous intrusions are shown on this
map? What rocks could A and B be?
B
A
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Faults
If faults are shown by straight lines then they
are vertical. If faults have a sinuous outcrop
then they are at an angle to the horizontal and
are probably reverse or thrust faults.
What type of faults are these? What is the
geological history of this area?
B
F2
A
C
E
D
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Faults
What type of fault is F2? How do you know? Why
does it appear to be in two sections?
granite
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Faults
The youngest rocks are always on the downthrow
side of a fault. You need to know how old each
rock is to find out the downthrow.
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Faults
Strike-slip faults are vertical but the movement
on them is lateral (sideways). If the far side
moves to the right the sense of movement is
dextral, if it moves to the left the movement is
called sinistral. Which way has this strike-slip
fault moved?
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Faults
What types of faults are F1 and F2? How can you
tell? Which one occurred first? How do you
know? What is the geological history of this area?
E
D
A
B
C
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Faults
F2
What types of faults are F1 and F2? Which
occurred first? How do you know?
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Which fault F1 or F2 is not vertical? How do
you know?Which fault F1 or F2 came first?How
do you know?What is the geological history of
this area?
A
B
C
D
E
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Answer the exam question about locality 1 on the
map above.
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Using evidence from Map 2, give one reason why
this is a dyke rather than a sill.
A
A
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Sills
What map evidence would you need to know to
convince you that the feature formed by Rock B
was a sill?
C
C
B
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Graphic logs
Asymmetrical ripples
Cross bedding
Give the evidence from the graphic log that shows
that these rocks were laid down in a fluvial
environment.
Erosional base
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Graphic logs
Complete the log using the descriptions contained
in Table 2.
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Complete this table about F2.
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Has the student got this geological history right?
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Fossil evaluation
A student identified this fossil as being Fossil
A. Was this correct?
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Fold wavelengths and amplitudes
wavelength
amplitude
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Evaluation of fold axes

• Are these statements true?
• the fold trends are NS
• the folds are symmetrical
• the fold wavelength is 200m.

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Geological history
A
What is the geological history of this area?
D
B
G
F
E
C
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Questions
State three pieces of evidence, either from
Map 3 or your fieldwork or knowledge, which
confirm the presence of an unconformity.
Draw and label on Map 3 the axial planes of two
folds to the east of Fault F2.
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Rock unit B was deposited in tropical, shallow
seas. What evidence from the photo and the
graphic log would confirm this statement?
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THE END