Slide 1 - NGfL Cymru by pengxiang


									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
  Question 1: Sedimentary Rocks

            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
Current direction incorrect by 180º
  Internal stratification incorrect
  No scale indicated on sketch
 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.
 Line of symmetry on brachiopod incorrect.

Fossil groups named as geological periods!
A Good Answer!
Byssus confused with limbs here!
Specimen Y was often confused
with Pecten as well as Pecans!
   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
 intersection is
 pointing to the
middle of the bed
All 4 items plotted correctly for 2 marks
  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
 Some candidates were quite
appreciative of the examiner’s
efforts in marking their papers
The End

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