DIAGRAMS IN GEOLOGY
Diagrams are very important in Geology – from fieldwork to working with maps (which are of course sophisticated diagrams). They give a visual description of the information you are trying to put into words. In exams, they can save a lot of time. Drawing diagrams is a skill which it is well worth perfecting, Yet many candidates seem to treat diagrams as unimportant – and lose marks accordingly.
The keywords are:
- compass directions
Instructions given in the question.
Draw a neat, well-drawn, freehand diagram, to scale, but without the frills.
- it does NOT mean that the drawing can be scrappy and illegible!
- marks will be awarded for precise labels, scale etc rather than the sketch itself;
- it is useful to put a frame around the drawing – it keeps it to the right size;
- when sketching clasts or grains, make them (and the scale) quite big, so that you do not have to draw too many of them;
- use diagrams printed in other questions as a guide to the expected quality.
The drawing must be more precise, with correct measurements, for example when drawing sections, maps and fossils;
- if it’s meant to be a straight line, use a ruler!
- if an angle is involved, use a protractor!
- if you are no good at drawing, don’t panic – the marks go for the measurements, labels, scale and other written information.
Caution – check the question to see if it says
- draw a diagram – draw one, but it is acceptable to draw two;
- draw diagrams – draw different views, for example of a fossil; if you draw only one diagram, you will lose marks
In WJEC exams, you may have to draw a diagram of a fossil specimen provided for the ‘practical’ exam. You must draw that particular specimen, not one which have seen in a text book.
Drawing diagrams in exams
Diagrams must be neat, clear, well-labelled and include a scale and title;
- draw carefully, but you don’t have to be an artist!
- draw simple line diagrams;
- use the lines to highlight the important geological aspects and to show relationships and interpretations; for example, a line can be a bedding plane, or a fault, or a trilobite suture line etc;
- put a frame around the drawing to keep it under control;
- the head of a label arrow must touch the feature being identified;
- use a ruler / protractor if appropriate;
- use standard symbols and shading; for example, brick pattern for limestone, but keep shading to a minimum to save time.
Preparation and revision
Look at the diagrams in past papers to see the standard of drawing of the examiners!
Prepare labelled, scale diagrams of:
- each type of fossil, from more than one viewpoint;
- each type of rock texture, such as porphyritic, flow banding, vesicular, porpyroblastic, granular, gneissose, schistose, well rounded, poorly rounded, well sorted, poorly sorted;
- each type of plate margin;
- each type of volcano;
- each type of sedimentary structure, especially the development of dune bedding.
Some of your prepared diagrams could be ‘copied’ from past papers.
Marks are for labels, annotations and scale rather than for the quality of artwork.
Remember –“ simple line diagrams with good labels”.