Hydrographic Bottom Type (HBT) codes can be output. What do they mean?
Many navies and engineering groups use these codes. The British Admiralty set used here (British Admiralty, 1973) are not very different from U.S. usage within USCG and NOAA. Some users of dbSEABED will find the codes familiar and helpful. Note that the terms at the front of the code are the most significant (abundant). For the clearest plottings, use the no-overlap options in your GIS and plot only the surficial seabed samples of an area. The codes output in EXT are either passed direct from naval/engineering HBT codings or re-codings of the lithological types that scientists have described in sediment samples. The codes output in CLC refer only to the gravel, sand, mud, rock and weed components present in a sediment or at a site. Note: Data for Hydrographic Bottom Type have not been included in this publication.
