The National Geological Map (MAGNA), created between 1972 and 2003 by the Geological and Mining Institute of Spain, is distributed in 1:50,000 scale sheets (1:25,000 in the specific cases of the Canary Islands, Ibiza-Formentera, Menorca, Ceuta, and Melilla). The Geological Map represents the nature of the materials (rocks and sediments) that appear on the Earth's surface, their spatial distribution, and the geometric relationships between the different cartographic units.
A geological cartographic unit is the grouping of one or more lithologies with a common age range, which is represented on the map at a defined scale or resolution. Each cartographic unit, as well as the different geological structures, is depicted on the map with its own symbology. The representation of these units on the map's topographic base provides some three-dimensional information, which is complemented by other geological data such as geological cross-sections, stratigraphic profiles, drillings, etc. The map's legend is a pictogram representing the spatial relationship of the various cartographic units (chronology, superposition, geometric relationship, lateral facies changes, etc.). It also includes structural, hydrogeological schemes and a location sketch of the sheet within its regional context.
