Geoscience Reference
In-Depth Information
Table 10.5 Information to record on a fi eld map. Level of detail is determined by time allocated and scale of
mapping. Conventional symbols used for plotting these data are given in Appendix A10 (Figure A10.3).
Information
Comments
Rock exposures
Location: extent if appropriate, nature (e.g. man-made). Brief notes of rock types or
facies, and other important information (e.g. fossils, index minerals, structures)
Structural data
Symbols and measurements (dip/strike, plunge/trend) for bedding, foliations,
lineations, fold axes, joint orientations, etc.
10
Notebook localities
Clearly label those localities where you have made detailed notes in your book
Specimen localities
Label the locations where samples were taken (rock, fossil, sediment, water, etc.); it is
best to link these directly to notebook localities
Photographs, sketches
Label where photographs were taken or fi eld sketches made if not at a notebook
locality
Major contacts
Lithological and tectonic: solid where observed, dashed where inferred.
Additional evidence
For example topographic features, drainage, soils, fl oat, vegetation (Figure 10.7a)
Superfi cial deposits
For example alluvium, glacial/fl uvioglacial material, sand, peat, river terraces, etc.
Degree of exposure
Comments on quality and quantity of exposure, weathering, soil cover, etc.
Hazards
Note of hazards not obvious from base map
rock unit letters and/or numbers. Symbols for important
structural data (Appendix A10, Figure A10.3) should be plotted
accurately in the fi eld, on or as close to their location as
possible, and then checked and inked in later (Section 10.6.1).
Accurate plotting encourages the mapper to check their
orientation frequently, which in turn keeps them alert to even
subtle shifts in structural trends. The convention is for the
locality to lie at the intersection of strike line and dip tick
(planar feature; Figure 10.7b), or the head of the arrow (linear
feature). Strike lines and arrows are important as they show, at a
glance, changes in the strike of the strata or trends of lineations,
and therefore indicate where to look for boundaries and features.
10.4.2 The evolving map
Major lithological divisions
There may be an existing stratigraphic scheme that you can
adopt or adapt to defi ne units of the various rock types within
the mapped area, in which case the criteria for the unit
defi nitions should be already documented. However, you may
need to apply your own unit defi nitions, either because you are
engaged in pioneering fi eldwork, or because the existing
scheme is inappropriate (e.g. not detailed enough). This is
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