Skills Earth Sciences

Tips for each map component

The maximum value of a scale is generally a round number, and they often include one or two smaller values to indicate shorter distances. For example, if your scale bar has a maximum length of 1 km, you may include extra divisions at 0.5 km and 0.25 km. Keep in mind, however, that values with more than two decimal numbers are uncommon and can be perceived as distracting, so try to avoid this.

Be consistent in the type of coordinate notation you use to present latitude and longitude, i.e. choose to either use decimal degrees (DD); degrees, minutes, seconds (DMS); or other notations (see e.g, Archison, 2012). In terms of style, you may choose to include latitude and longitude values on all sides of a map or only on one side (e.g., top and right). Similarly, you may choose to include a grid inside or tick marks on either side of the map. You may also decide to include or exclude zero values of minutes and seconds in the DMS notation, i.e. 32°0”0’ N vs 32° N. Values on the left- and right-hand side of a map are generally vertical. If you are unsure of the style you need to use for your assignment, check what the conventions are in peer-reviewed literature in your research field, or ask the lecturer/editorial board for their preferences.

Organise your legend by grouping certain similar features together and ordering them in a logical way. Legends are part of your figure and may be included as insets in your map (if they do not cover important information), or they can be set outside of your reference system if that is more appropriate. Try to keep your figure clean and uncluttered, but also minimalise unused space in your figure when you include a separate legend below your map, for example. Adapt the layout of your legend accordingly.

Each sub-field of geoscience uses field-specific symbology to indicate common features mapped for the purposes of that field. Adhere to the symbology in your field of research and look up whether any open-source tools are available to simplify their implementation. For example, the United States Geological Survey (USGS) has made a geological mapping symbology package available for Adobe Illustrator.

Be considerate of your audience’s perception of colour use in your map and make sure your colours can only be interpreted in the way you want them to be. Keep maps simple and include symbols where possible to avoid confusion. For general information on colour use, see Colour use in data visualisation. Additionally, be aware of the colour use conventions in your field. For example, geological maps often use specific colours for certain rock types (e.g., igneous rocks are often pink) or ages. These are conventions, not rules, but keep an eye out for patterns used in your research field and apply them to your own maps for convenient and clear communication with your peers.

Geoscientific maps may include multiple aspects, such as line features (e.g., drainage networks or faults) and polygonal features (e.g., geomorphological or geological features), but it is often favourable to focus on a single aspect for clarity. For example, if you are studying the geomorphology of an area and you also want to highlight its geology as background information, it will not be beneficial to display both aspects in a single map as the shaded areas of geomorphological and geological units will overlap. In such cases you may choose to present two separate maps, a geomorphological and a geological map of the same area. Keep in mind that if you want your audience to compare both maps and understand the link between geomorphology and geology, your maps should both have the same reference frame and scale, and they should include some details that can be used for location recognition (e.g., place names or distinct rivers/lakes).