Final answer:
In an atlas, an X in a circle symbol typically marks a significant location or feature. It's a cartographic mark to flag areas for further attention. In other contexts, it can denote experimental points or areas needing caution.
Step-by-step explanation:
In an atlas, different symbols are used to represent various features or data points. The specific symbol mentioned, which looks like an X in a circle, often denotes a particular location of interest or significance, such as the location of a geological feature, a historical event, or a significant structure.
This symbol is a type of mark used by cartographers to indicate a point that may require further attention or investigation by the user of the atlas. In some cases, these symbols may also be used in scientific figures to represent experimental points or in texts to highlight areas for supplemental content or caution.