WJEC A2 Geology

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WJEC A2 Geology
BGS Mapwork
I.G.Kenyon
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BGS 150.000 scale maps
1mm on the map represents 50m on the ground Grid
squares are 1 km² and have sides of 2cm on the
map
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BGS 125,000 scale maps
1mm on the map represents 25m on the ground Grid
squares are 1 km² and have sides of 4cm on the
map
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BGS Maps are produced in solid and solid and
drift editions Solid maps show only the
fully lithified rocks Solid and drift maps
show the lithified rocks plus any recent
sediments deposited on top
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Solid Geology Cockermouth Sheet 23 150.000
Permo-Triassic Rocks
Carboniferous rocks
Recent drift deposits such as alluvium and
boulder clay not shown
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Solid and Drift Geology Clitheroe Sheet 68
150,000
River Terrace Deposits
Alluvium
Solid Geology
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Structures to Identify on BGS Maps 1
Beds direction of dip/angle of dip Beds
strike direction/orientation Anticlines/synclines/
monoclines Fold axes/axial plane of
folds Domes/basins Symmetrical/asymmetrical
folds Plunging folds Open/tight/recumbent/overturn
ed folds
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Structures to Identify on BGS Maps 2
Normal faults/reverse faults/thrust faults Tear
faults sinistral/dextral/step
faults Graben/rift valley/Horst/block
mountain Unconformities-angular/parallel/heterolit
hic Inliers/outliers Lava flow/sill/dyke/pluton/mi
neral veins Metamorphic aureole Inverted relief
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Symbols on BGS Maps 1
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Drift Symbols on BGS Maps
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Generalized vertical sections are given on BGS
Maps
This is a vertical log of all the rock types
present in chronological order with the oldest at
the base and the youngest at the top On 150,000
maps the scale is often 110,000 On 125,000
maps the scale is often 14,000 However scales
can vary-check carefully on each map that you
are studying
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Part of generalized vertical section from Cheddar
Sheet ST45 125,000
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Part of the generalized vertical section from
Hawes Solid and Drift 150,000 Note that rock
types and ages of beds are given Unconformities
are clearly indicated in the section It is vital
that the vertical section is studied carefully in
conjunction with the map in order to interpret
all of the geological structures
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Cross sections are also included on BGS maps and
should be studied carefully along with the
vertical section and map
From Hawes Solid and Drift 150,000
You do not have to construct cross sections from
BGS maps at A2!
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In addition to geological structures, you will
be asked questions with a GL3 bias These could
include evaluating the suitability of certain
locations for the construction of roads, landfill
sites, housing estates, reservoirs, power
stations, dams or tunnels Questions relating to
the causes of landslips are also a possibility
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Sometimes additional maps are included on the BGS
geology maps These may include magnetic, gravity,
radon, isostatic or mineralogical data Questions
related to this additional data may be
asked in relation to the geological
map
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Okehampton/Dartmoor Map
Geology and Gravity Anomalies
Gravity anomalies (contoured in milligals). The
negative gravity anomaly is due to the granite
being of lower density than the surrounding rocks
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Okehampton/Dartmoor Map
Geology and Magnetic Anomalies
Aeromagnetic anomalies (contoured in nanoteslas)
Magnetic disturbances
skirting the granite are due to mineralisation
in the Lower Carboniferous rocks and basic
intrusions at depth
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The End
Ash deposits of the Las Canadas Volcano,
Tenerife, Canary Islands