In order to improve the geological maps o f the Badalona area o f Barcelona, a geological scheme o f the area was generated by the GIS program which was used to digitize information from orthomaps. Ground truth was provided by field work carried out at a series of the most important geological locations of the area. Information collection was carried out by secondary school students supervised by Earth Sciences teachers. The use of geographical information systems (GIS) combined with field data provides an important new tool for use In the improvement of geological and scientific knowledge.