Geoscience Reference
In-Depth Information
Here are some ideas for producing a good sketch; these are also
summarized in Figure 4.4 (p. 62).
•
Space:
Allow plenty of space in your notebook for the
sketch so that there is room to add labels summarizing
observations, scale and orientation, detailed drawings of
pertinent parts (insets), cross references to later sketches or
other written notes, and labels summarizing points of
interpretation. It is also much easier to sketch at a larger
scale; if you are not good at sketching it may be tempting to
push the sketch into one corner of a page of the notebook
but this is making it far more diffi cult for yourself. So, take
your time and use a whole page or even two facing pages
for the sketch and labels. Don't spoil a good sketch with too
many labels though or place labels on the sketch so that
they obscure parts of it. Figure 4.2a (p. 58) shows good use
of space but it could have been improved by placing the
labels that are on top of the line drawing off to one side
with tag lines in a similar manner to Figures 4.3c and 4.3f.
4
•
Scale:
All sketches should include a scale. How accurate
the scale of the sketch is will depend on the purpose of the
fi eldwork. However, it is important to get the features into
proportion. For sketches of cliffs, hillsides, etc., once you
have established a scale for a small portion (e.g. from the
height of a person (Figure 4.2a) or size of a vehicle) use
your thumb held at arm's length to estimate the scale for
the remainder of the sketch.
•
Orientation:
All sketches should include an orientation
relative to north and a clear indication as to whether it is a
plan view, oblique view or cross-section (e.g. cliff). The
simplest and most straightforward way of adding an
orientation is to use a north arrow for any plan views and
to label the ends of cross-sections with the nearest compass
points, e.g. NW-SE or NNW-SSE. Alternatively, you can
label your viewpoint to the centre of the sketch, e.g. looking
due southeast or looking towards 135°. The latter method is
popular for views of oblique surfaces but is not
recommended for cliff sections because it is not as clear.
Figure 4.3
Example sketches from different authors' notebooks showing features on a wide variety of scales.
(a) Simple cross-sectional sketch showing wavy lamination in a sedimentary rock. (Notebook of Paul Temple,
Open University student). (b) Zoned phenocryst showing shape of crystal zones. (Notebook of Kate Bradshaw,
The Open University, UK.) (c) Labelled cross-sectional sketch of pebble bed. (d) Large-scale sketch cross-section
across a hillside in Argentina. (c and d: Notebook of Angela L. Coe, The Open University, UK.) (e) Complex
three-dimensional sketch of trough cross-stratifi cation in a block of sandstone. (Notebook of Kate Bradshaw, The
Open University, UK.) (f) Sophisticated sketch of the geological relationships of various rock bodies in a
kimberlite complex, South Africa. (Notebook of Richard Brown, The Open University, UK.)
