Superficial Geology (250k) This layer shows the superficial (drift) geology of Northern Ireland at 1:250,000 scale. For each rock unit there is a brief generalised description under the following headings. LEX_D: Description of the selected polygon. LEX_RCS: Map code as it appears on the published 1:250,000 map. RCS_D: Decription of the deposit. VERSION: Version of the data. RELEASED: Date of release/update of the data. Persons interested in the detailed geology of particular sites should consult the latest large-scale maps or the Geological Survey of Northern Ireland at:- Geological Survey of Northern Ireland Colby House Stranmillis Court Belfast BT9 5BF