Links between map database systems from different scales

The results of BGS geological survey are mostly recorded OIl 1:10000 scale maps, and published at 1:50 000 and smaller scales. The maps are generalised by removal of detail, smoothing lines and adjusting to fit the new base map. Digital map productiOD still requires the delivery of traditional maps, in order to be consistent with p~t publications and to retain the customer base. But, while the map is unrivalled for presentation, new methods for data collection, storage, manipulation and retrieval are available in a digital environment. Constraints impooed by fixed scales and the need to fit specific base maps must eventually be overcome. Meantime, it is desirable to distinguish clearly between the needs of the scientific database and purely cartographic requirements, which may be transitory. It is recommended that as far as practicable, the scientific data from all scales should be held in a single database. Records for various ranges of generalisation should be distinct, and should have precise counterparts at each scale, where possible derived from the survey scale by algorithm. Stratigraphical relationships are involved in generalisation, and must be available as part of the database. Version control is vital to continuous revision, but made partiOJlarly complex by the need to update generalised maps.