A collection of 1:63 360 and 1:10 560 geological maps of Ireland. The maps were firstly created by the Geological Survey of the United Kingdom and Ireland up until 1905 when the Geological Survey of Ireland was transferred to the Department of Agriculture and Technical Instruction for Ireland. Following this point, the maps were created and published by the Geological Survey of Great Britain (later to become the British Geological Survey). The maps range from 1853 to 1953. Geological maps represent a geologist's compiled interpretation of the geology of an area. A geologist will consider the data available at the time, including measurements and observations collected during field campaigns, as well as their knowledge of geological processes and the geological context to create a model of the geology of an area. This model is then fitted to a topographic base map and drawn up at the appropriate scale, with generalization if necessary, to create a geological map, which is a representation of the geological model. Explanatory notes and vertical and horizontal cross-sections may be published with the map. Geological maps may be created to show various aspects of the geology, or themes. These maps are hard-copy paper records stored in the National Geoscience Data Centre (NGDC) and are delivered as digital scans through the BGS website.