WJEC GL4 Feedback 2006 Principal Examiner Ian G. Kenyon.
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Transcript of WJEC GL4 Feedback 2006 Principal Examiner Ian G. Kenyon.
Mark Range
25 to 90 out of 96
An accessible paper with only 46 of the 819 candidates scoring less than 40 out of 96
Areas of Weakness
Poor understanding of the formation of cross bedding and the internal structure of a dune
Diagenetic changes poorly understood, actual process names rarely stated
Many candidates were unable to suggest reasons to explain the lack of fossils
in the sedimentary sequence
Question 1: Sedimentary Rocks
Wind/current direction incorrect by 180º
Internal structure confused
Absence of any scale on sketch
Only annotation refers to marine processes
A Good Answer!
Internal structure correct
Current direction appropriate
Dune migration correctly plotted
No scale indicated though!
Question 2: Palaeontology
Areas of Weakness
Some candidates only drew planes of symmetry on either specimen A or B
A number of candidates failed to identify the fossil groups. Howlers
included ammonite and tripod!
Shell morphology and mode of life poorly understood. Many contradictory
statements made here.
Question 3: Metamorphism
Areas of Weakness
Lack of explanation of origin of texture 3b. Many students simply
described the texture
Inability by many to describe two simple practical tests to distinguish between marble and metaquartzite
Limited understanding by many of the conditions of dynamic metamorphism
Answers to this question revealed glaring gaps in very basic geological knowledge by many candidates!
Quartz has cleavage!
Too easy for A2? It proved to be a really good discriminator!
Many candidates failed to link marble with calcite and metaquartzite with quartz to devise simple
practical tests to distinguish them apart.
Question 4: Structural Geology
Areas of Weakness
Drawing of Interlimb angle, overturned limb and cleavage/bedding intersection
poorly attempted by many
Amplitude is not understood by the majority of candidates
Many students are poor at evaluating geological statements. They seem to agree
or disagree with everything or contradict themselves time and again.
A typical answer scoring half marks
Only part of the interlimb angle
is indicated
Axial plane most commonly plotted
correctly
Bedding/cleavage intersection is
pointing to the middle of the bed
Amplitude
The same mistakes made as in previous years
Candidates simply measured the distance between the crest
and trough of the fold
Amplitude is half the distance between crest and trough
Not the perfect answer but a good attempt at an evaluation and worth full marks!
This question was another good discriminator.
Section B – BGS Mapwork
Key to symbols omitted
Slight difference in colour between map and generalised vertical column
Metamorphic aureole symbol rather faint
Candidates did not seem to be disadvantaged by this!
Question 5 (a) (i)A number of candidates regularly fail to realise that
two directions are required for the strike credit
A small hyphen was inserted in the response box to help candidates!
A small number of candidates took this as a signal to leave the box blank!
Question 5 (a) (ii)Description of folding in box A was
well done by many candidates
Weaker candidates failed to refer to symmetry or quote dip values and strike orientations
Only the better candidates referred to a basin structure or plunge directions
Question 5 (b)A good understanding shown here by many candidates.
Graben structure recognised by the majority with the central block being downthrown between 2 parallel faults
A small number of candidates found it a challenge however-see below!
Question 6 (a)Generally well answered but the answers
for the angle of dip of the Ochil Fault were bewildering at times and included:
7, 15, 45, 99, 105, 115, 129, 145, 171 degrees
Only a minority of candidates noticed that the vertical scale had been exaggerated by x 2
Credit was given for reference to apparent dip as the section may not have
been at right angles to the fault plane
Question 6 (c)
The examiners appreciate that the size of the boxes restricted candidates from giving fully detailed reasons.
A few candidates mistakenly reasoned the relative ages of the three boxes rather than each of the pairs in turn!
Question 7 (a)The majority of candidates identified (H) Pluton and (P) Dyke
The better candidates drew clear cross sections to explain how the angle of the contact affected the width of the aureole
Question 7 (b)Some excellent answers here with very detailed annotations
Some candidates mixed up baked and chilled margins
A small number of candidates left this completely blank
Question 8
Some candidates gave non-geological factors for which little credit could be given
Reference to noise, air quality and eyesore were common errors
The label on the cross section reading ‘superficial deposits not shown on the map’
seemed to cause confusion among some candidates when evaluating site G
Question 8
Some candidates ignored ‘landfill’ and referred to problems of opening up the
quarry for further extraction of rock
Most candidates decided either good or bad for each site rather than evaluating all the evidence
Candidates should be aware that all sites have the potential to be a landfill site if there is sufficient engineering employed-e.g. clay liner
Question 8
Good discussion of geological factors included:
Rock permeability and dip direction of beds
Synclinal structure of argillaceous rocks
Possibility of fault reactivation
Mining history and potential for subsidence
Impermeability of igneous rocks
Very few candidates attempted to put the three sites in a possible rank order from most to least suitable