Basic geological mapping has been at the core of geology since its inception in the late eighteenth and early nineteenth centuries when it was realized that rocks of similar composition and fossil content could be traced across country. The most famous first geological map was of England, Wales, and part of Scotland by William Smith, a canal engineer, who single-handedly completed the geological map by 1801. It was published as a hand-painted, 8 ft tall by 6 ft wide edition in 1815 (Figure 3.1), and this unique map can be viewed at Burlington House, London, the headquarters of the Geological Society of London. The map colours he used for the different strata were light purple for the oldest rocks that crop out over most of Wales and sea-blue for the narrow ribbon of Carboniferous limestone that snakes its way across the country. Similar colours are still used in modern-day geological maps of the United Kingdom. Most importantly, a geological cross-section of England was included on the map which predicted the strata beneath the countryside, thereby providing the first 3D view of the geology. This map was an amazing achievement and its overall accuracy has borne the test of time – it is well worth reading the fascinating story behind the creation of this map – The Map That Changed the World by Simon Winchester (2001). Over the following two centuries, most of the world has been geologically mapped at various scales, but the impetus to teach and continue this essential skill is diminishing, even within the national geological surveys – a great loss.