Field maps - what they look like

Field maps are important scientific documents. They are interpretative in that quite a lot of the geology will be inferred on the basis of sparse direct observations of rocks coupled with other secondary evidence (vegetation, topographic features etc). These examples show how to present data on field maps. They are all "real" - created on field classes in NW Scotland (by Rob Butler) uinder "normal" conditions.

All decisions on what should go on the map are made and recorded in the field and shown first on a field slip in pencil (graphite and colour). An example of a field slip taken directly from the field is shown here. To get this quality requires good, sharp pencils and some care. Work in pencil so that you can rub out boundaries if you change your interpretation while mapping. Note that strike-dip symbols are drawn on in the field - they help you while mapping to predict what's coming up next.

After a day in the field all the information you have collected, together with the interpretations you've made on boundary positions etc, should be inked in. The reason for this is to preserve your data - pencil is readily rubbed out and smudged. You can see two examples of inked-in field slips.

One comes from a simple boundary (sediments on gneisses) from the Eriboll district. The mapping of this boundary took 3 hours (moving quickly) - notice the amount of data. Inking in took another hour (in the evening). The other map comes from southern Assynt and shows a greater range of rock type and orientation data. None of thse scenes show the complete map. All maps should have a key (to rocks and symbols), a scale bar and numbered grid lines.

Another example of a field map from NW Scotland can be found here. This one comes from Mill na Claise (Gairloch) and shows some slightly more complex geology.

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