GEOLOGY INTERMEDIATE 2
Exercises on
Geological Structures and Relationships
Marking Instructions
1 (a) (i)
Diagram 1 (a)
10m
fault
(ii)
Younger beds on the right have been moved down so they now lie
against older beds on the left. Outcrops on the left of the fault are
repeated on the right of the fault.
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1 (b) (i)
Diagram 1 (b)
10m
(ii)
Older beds on the right have been moved up so they now lie
against younger beds on the left. Beds which do not outcrop on the
left of the fault now outcrop on the right of the fault.
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1 (c) i.
Question 1 (c)
ii.
Younger beds on the right have been moved down so they now lie
against older beds on the left. The outcrop pattern is the same on
both sides of the fault but the outcrops have been moved sideways
along the fault.
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1 (d)
i.
Question 1 (d)
ii.
Older beds on the right have been moved up so they now lie
against younger beds on the left. The outcrop pattern is the same
on both sides of the fault but the outcrops have been moved
sideways along the fault.
The same shift of outcrops seen in 1(c) and 1(d) would be
produced by a tear fault. Thus, the outcrop pattern alone
does not allow you to distinguish between a tear fault and a
fault on which vertical movement has taken place.
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1 (e)
i.
Diagram 1 (e)
ii.
Younger beds on the right have been moved down, so they now lie
against older beds on the left.
When an anticline is moved down the outcrop of the beds in the
core of the fold becomes narrower.
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1 (f)
i.
Diagram 1 (f)
ii.
Older beds on the right have been moved up so they now lie
against younger beds on the left.
When an anticline is moved up the outcrop of the beds in the core
of the fold becomes wider.
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1 (g)
i.
Question 1 (g)
ii.
Younger beds on the right have been moved down so they now lie
against older beds on the left.
When a syncline is moved down the outcrop of the beds in the core
of the fold becomes wider.
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1 (h)
i.
Diagram 1 (h)
ii.
Older beds on the right have been moved up so they now lie
against younger beds on the left.
When a syncline is moved up the outcrop of the beds in the core of
the fold becomes narrower.
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Completion Exercises for Maps
2 (a)
Map 2 (a)
Rocks on the right have been displaced downwards, so younger
conglomerate on the right now lies adjacent to older mudstone on
the left.
2 (b)
Map 2 (b)
Rocks on the right have been displaced upwards, so older
limestone on the right now lies adjacent to younger mudstone on
the left.
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2 (c)
Map 2 (c)
Rocks on the right have been displaced downwards, so younger
rocks on the right now lie adjacent to older rocks on the left.
2 (d)
Map 2 (d)
Rocks on the right have been displaced upwards, so older rocks on
the right now lie adjacent to younger rocks on the left
The same shift of outcrops seen in 2(c) and 2(d) would be produced by a
tear fault. Thus, the outcrop pattern alone does not allow you to
distinguish between a tear fault and a fault on which vertical movement
has taken place.
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2 (e)
Map 2 (e)
Younger beds on the right have been moved down, so they now lie
adjacent to older beds on the left.
When an anticline is moved down, the outcrop of the beds in the
core of the fold becomes narrower.
2 (f)
Map 2 (f)
Older beds on the right have been moved up, so they now lie
adjacent to younger beds on the left.
When the anticline is moved up, the outcrop of the beds in the of
the fold becomes wider.
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2 (g)
Map 2 (g)
Younger beds on the right have been moved down, so they now lie
adjacent to older beds on the left.
When a syncline has been moved down, the outcrop of the beds in the
core of the fold becomes wider.
2 (h)
Map 2 (h)
Older beds on the right have been moved up, so they now lie adjacent to
younger beds on the left.
When a syncline has been moved up, the outcrop of the beds in the core
of the fold becomes narrower.
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2 (j)
Diagram 2 (j)
Because there has been no vertical movement on the fault, the widths of
the outcrops of the anticlines and synclines are the same on both sides
of the fault.
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2 (k)
Diagram 2 (k)
The rocks on the right have been displaced downwards, so younger
rocks on the right now lie adjacent to older rocks on the right now lie
adjacent to older rocks on the left.
Because the rocks on the right have moved downwards, the outcrop of
the rocks in the core of the anticline has become narrower and the
outcrops of the rocks in the cores of the synclines have become wider.
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Establishing Age Relationships
3 (a)
B→F→E→A→D→C
3 (b)
D→E→C→B→F→A
3 (c)
D→C→B→F→A→E
3 (d)
C→A→D→E→F→B
3 (e)
F→B→A→C→E→D
3 (f)
E→D→A→F→C→B
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BLOCK DIAGRAMS
4 (a)
i.
Syncline
ii.
Anticline
iii.
Thrust fault
iv.
Unconformity
v.
Dyke P has been broken and displaced upwards on the left hand side of
fault F. The upraised block has been eroded down so all traces of the
dyke on the left of the fault have been removed.
vi.
C→B→F→A→E→D
4 (b)
i.
Formed by the deposition of sediment on an older erosion surface. (It
represents a break in the stratigraphical succession)
ii.
One
iii.
On surface S, gneiss overlies sandstone.Gneiss is a metamorphic rock
so it cannot have been deposited on top of the sandstone. The surface
separating the gneiss and sandstone must be a fault plane and not an
unconformity.
iv.
B→A→E→F→D→C
4 (c)
i.
Dyke
ii.
Sill
iii.
Movement on the fault has been mainly in a horizontal direction so
dolerite P shows a marked displacement. In addition to a large horizontal
movement there has been a slight vertical movement which has slightly
moved the granite.
Or
Movement on the fault has been at a slight angle to the horizontal.
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iv.
4 (d)
i.
ii.
4 (e)
i.
F→D→A→E→C→B
B,C, E
D→E→B→C→F→A
Batholith or stock
ii.
Dyke
iii.
It is transgressive
Or
It moves from one level to another
Or
It cuts the fault so it must be intrusive
iv.
E→C→F→A→B→D
4 (f)
i.
Two
ii.
Five
iii.
It is overlain by a fossil soil. Soils from only on land.
iv.
C
v.
B→C→E→F→A→D
4 (g)
i.
Normal fault
ii.
Reverse fault
iii.
Dyke
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iv.
4 (h)
i.
D→B→E→A→F→C
Batholith or stock
ii.
The dolerite cuts faults FP,FQ and FR. It must be intrusive.
iii.
Fault FQ displaces fault FP but it does not displace the horizontal lava.
Movement on fault FQ must be in a horizontal direction which means
that it is a fear fault.
iv.
Fault FP
v.
Fault FR
vi.
C→A→F→B→D→E
4 (j)
i.
Anticline
ii.
Syncline
iii.
Reverse
iv.
Granite – dyke
Dolerite – sill
Gabbro – stock
v.
E→F→A→D→B→C
4 (k)
i.
Unconformity
ii.
Normal
iii.
Reverse
iv.
No displacement is visible. You cannot tell what type of fault it is without
seeing how the rocks have been moved.
v.
Hornfels – red shading in mudstone close to the granite
Marble – green shading in limestone close to the granite
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Metamorphic quartzite – blue shading in sandstone left of fault FR close
to gabbro
vi.
Falls; down; faster; flooded; rises; raised beaches
vii.
B→A→D→F→C→E
MAPS
5 (a)
i.
Dyke
ii.
Sill
iii.
Unconformity
iv.
Tear fault
v.
East side
vi.
D→E→F→A→C→B
5 (b)
i.
Thrust fault
ii.
Ancient volcano or neck or plug (or vent)
iii.
Anticline
iv.
East. Younger limestone on the east is adjacent to older sandstone on
the west. The eastern side must have been moved down.
Or
The outcrop of the beds in the care of the anticline is narrower on the
eastern side of the fault. This narrowing takes place when beds folded
into the form of an anticline are moved down.
v.
West. Younger limestone on the west is adjacent to older sandstone on
the east. The western side must have been moved down.
Or
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The outcrop of the beds in the core of the anticline is narrower on the
western side of the fault. This narrowing takes place when beds folded
into the form of an anticline are moved down.
vi.
5 (c)
i.
E→C→A→F→B→D
Syncline
ii.
iii.
Tear fault. The dolerite dyke has been displaced. Because the dyke is
vertical, movement on the fault has been horizontal.
Or
The width of the outcrop of the synclinally folded beds is the same on
both sides of the fault. This shows that there has been no vertical
movement on the fault.
iv.
South West Younger sandstone on the South-West is adjacent to older
limestone on the North-East. The South–Western side must have been
moved down.
Or
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The outcrop of the beds in the core of the syncline is wider on the SouthWestern side of the fault. This widening takes place when beds folded
into the form of a syncline are moved down.
v.
North–East Older sandstone on the North–East is adjacent to younger
sandstone on the South–West. The North–Eastern side must have been
moved down.
Or
The outcrop of the beds in the core of the syncline is wider on the NorthEast side of the fault. This widening takes place when beds folded into
the form of a syncline are moved down.
vi.
B (the outcrop on the downthrown side of fault FR is smaller than the
outcrop on the South-West side of the fault. The narrower part of the
gabbro intrusion has been moved down to lie adjacent to the wider part.)
vii.
B→F→C→E→A→D
5 (d)
i.
It gives off transgressive side shoots.
Lava flows do not intrude adjacent rocks.
ii.
Dyke
iii.
The fault runs along the line of the dyke (dolerite P).
Tear fault (Because of the displacement shown by the outcrop of the
granite.)
iv.
Batholith or stock
v.
Volcano is in North-West corner of map.
vi.
D→C→A→E→F→B
5 (e)
i.
Letter A should be written on the limestone
ii.
Letter S should be written in the middle of the mudstone
iii.
North-West side. Older limestone on the North-West side of the fault is
adjacent to younger sandstone on the South-West side of the fault.
Thus, the rocks on the North-West side have moved up.
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Or
On the North-West side of the fault the outcrops of the beds in the cores
of the anticlines are wider than those on the South-East side. Such
widening takes place when beds folded into the form of an anticline are
moved up.
Or
On the North-west side of the fault the outcrops of the beds in the cores
of the synclines are narrower than those on the South- East side. Such
narrowing takes place when beds folded into the form of a syncline are
moved up.
iv.
v.
5 (f)
i.
E→F→A→C→B→D
Sandstone
ii.
Conglomerate P
iii.
Unconformity
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iv.
Thrust fault
v.
Dome
vi.
South-East
Older limestone on the South-East side of the fault is adjacent to
younger mudstone on the North-West. The older rock on the South-East
has been moved up to lie at the same level as the younger rock on the
North-west.
Or
The outcrop of the folded rocks is wider on the South –East side of the
fault. Such widening occurs when rocks folded into the form of a dome
are moved up.
vii.
Tear fault
viii. C→B→F→D→A→E
5 (g)
i.
Dyke
ii.
Volcanic plug
iii.
The oldest rock (mudstone) is in the core of the fold. (If the fold was a
syncline the youngest rock would be in the core.)
iv.
Tear fault
The rocks on the North-West side of the fault have been moved to the
South-west by about 200m.
v.
Normal fault
Rocks in the South-East side have moved down. (Younger limestone on
the South-East side is adjacent to older mudstone on the North-West
side. The limestone has been moved down to be at the same level as
the mudstone. Also, the rocks in the care of the anticline have a
narrower outcrop on the South- East side. Such narrowing means that
rocks folded into the form of an anticline have moved down.)
vi.
The rocks on the South-East side have been moved 400m to the SouthWest.
vii.
F→A→B→E→D→C
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viii. There are no cross cutting relationships to allow you to establish relative
ages.
5 (h)
i.
ii.
5 (j)
i.
A,D,E
D→E→F→C→B→A
67o or 247o
ii.
A, C
iii.
Syncline
iv.
North–East
When the rocks in the core of a syncline are moved down, the width of
the outcrop increases. The outcrop of the mudstone is wider on the
North-East side, so the North-East side has been thrown down.
v.
The intrusion which forms granite S has vertical walls, so the intrusion
has a cylindrical shape. Vertical displacement will not change the crosssectional shape of the cylinder.
vi.
B→F→A→E→D→C
5 (k)
i.
Tear fault
ii.
Sandstone
iii.
Basin
iv.
South-east
When rocks folded into the form of a dome or syncline are moved down,
the width of the outcrop increases. The conglomerate has a longer or
wider outcrop on the South-east side of the fault so the South-east side
has been thrown down.
Or
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The conglomerate has been moved down to lie adjacent to older
limestone.
v.
E→D→C→F→A→B
SECTIONS
6 (a)
i.
A piece of rock picked up and carried by magma which is subsequently
enclosed by igneous rock formed from the magma.
ii.
Schist and conglomerate
iii.
Reverse
iv.
Unconformity
v.
Deposited by moving ice
vi.
E→B→C→A→F→D
6 (b)
i.
It is transgressive
or
It changes from one level to another
or
It intrudes along two fault planes
ii.
Batholith or stock
iii.
Normal
iv.
3 metres
v.
C→F→E→A→D→B
6 (c)
i.
Thrust fault
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ii.
Unconformity
iii.
Dyke
iv.
Sill.
The same limestone is found above it and below it. To separate the
limestone like this it must be intrusive.
v.
There are no cross cutting relationships to allow you to establish relative
ages.
vi.
C→A→F→D→B→E
6 (d)
i.
Syncline
ii.
Anticline
iii.
Three
iv.
When lava is erupted into the sea rapid chilling causes the surface of the
lava flow to solidify while the inside remains liquid. The liquid lava bursts
through the solid skin in blobs which solidify as pillows.
v.
D→E→A→B→F→C
6 (e)
i.
Thermal or contact metamorphism
ii.
Metamorphic aureole
iii.
Mudstone is more easily metamorphosed than sandstone.
Or
The minerals in mudstone are more easily changed by heat than the
minerals in sandstone.
Or
New minerals grow more easily in mudstone than in sandstone.
Or
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Mudstone has a wider variety of minerals than sandstone. This makes
mudstone more susceptible to change when it is heated.
iv.
Batholith or Stock
v.
Sill
vi.
It transgresses or changes levels so it must have been intruded
vii.
B→D→A→F→E→C
6 (f)
i.
P - Thrust fault
Q - Thrust fault
R - Unconformity
S - Unconformity
ii.
B
iii.
E→F→D→A→C→B
6 (g)
i.
Normal
ii.
It cuts through faults so it must be intrusive
iii.
Dyke
iv.
The rocks to the right of dolerite S have been displaced downwards
relative to those on the left. This displacement occurred by movement on
a fault before the dolerite was intruded.
v.
D→B→C→E→F→A
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