Geoscience Reference
In-Depth Information
3
Introduction to fi eld
observations at
different scales
Angela L. Coe
3
3.1 Introduction: What, where and how?
Going out into the fi eld and examining rocks at an exposure for
the fi rst time, or even subsequently, might well reveal features
that you cannot recognize, do not understand or cannot
explain. Overcoming this challenge is a matter of careful study,
persistence and experience. This chapter provides an
introduction to some of the key questions for geological
fi eldwork and a systematic way of overcoming the challenge of
collecting data and understanding an exposure. The key
questions are:
1. What are the objectives of the fi eldwork? (Section 3.1.1)
2. Where is the best place to gather the data? (Section 3.1.2)
3. How do I precisely determine my position? (Section 3.1.3)
4. Faced with a new exposure, where do I start? (Section 3.2)
5. What is the most appropriate way of collecting the data?
(Section 3.3, Chapters 5-10)
3.1.1 Defi ning the fi eldwork objectives
Fieldwork is undertaken to address particular scientifi c
problems; these should be clearly defi ned before going into the
fi eld. This is because it is very easy, when out in the fi eld and
faced by excellent rock exposures, to become distracted by
other interesting features or to spend too long on particular
aspects. For instance, if the objective of the fi eldwork is to
determine the orientation, sense and amount of displacement
on a series of faults bounding a sedimentary basin then the
only
critical feature of the sedimentary beds required is a
knowledge of the stratigraphy to determine the amount of
displacement across the faults. On the other hand if the
objective of the fi eldwork is to produce a graphic log of the
succession then the details of any later structural movement are
If you are faced with a lot of
good exposure and do not
know where to start, break it
down into small parts.
Concentrate on a section of
one cliff face fi rst. If possible
use a face that is either
roughly perpendicular or
parallel to the strike of the
beds.
