The present experimental study is based on evidence obtained on land showing that in areas covered by ancient continental ice the drift is to a large extent of local origin so that the quality of the rock ground is determinable from the composition of the drift with a great degree of probability. A geological map based on the bottom sampIes has accordingly been sketched of the Bothnian Sea area. Echo sounding has been made use of in determining the quality of the bottom at the sample points as well as for the interpretation of the morphological picture of the sea bottom. In order to obtain a uniform interpretation basis as weIl as a statistically adequate amount of stone grains from each sampIe, 2-16 mm has been chosen as the grain size for the pebble counts.

From 1983 until 1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions. At the time it was the most extended data compilation on ferromanganese deposits world wide. Initially published in a proprietary format incompatible with present day standards it was jointly decided by AWI and NOAA to transcribe this legacy data into PANGAEA. This transfer is augmented by a careful checking of the original sources when available and the encoding of ancillary information (sample description, method of analysis...) not present in the NOAA-MMS database.

Supplement to: Veltheim, Valto (1962): On the pre-Quaternary geology of the bottom of the Bothnian Sea. Geological Survey of Finland, Bulletin - Bulletin de la Commission Géologique de Finlande, 200, 166 pp