Accumulation rates of 1-2 mm/million years are reported for manganese crusts on deep-sea rocks. These rates are the same as most reported accretion rates for manganese nodules suggesting a similar mechanism for this formation. Manganese crusts on large deep-sea rocks provide convincing evidence that net sediment accumulation in these areas has been zero for many millions of years.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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: Moore, Willard S (1973): Accumulation rates of manganese crusts on rocks exposed on the sea floor. In: Phase I Report - Inter-University Program of Research on Ferromanganese Deposits of the Ocean Floor. Seabed Assessment Program, IDOE, NSF, Washington D.C., USA, 93-96