Translation table for sediment grain size fractions

The sediment grain size fractions map is based on an estimate of the percentage content of each fraction within each of the standard grain size categories represented in the sediment grain size map.

The translation table shows the percentage content per grain size category of four grain size fractions – mud, sand, gravel, cobbles and boulders, rock and hard sediments. It is important to note that the percentage values are indicative estimates and not absolute measured values.

These values are used to create maps giving a simplified view of the distribution of each grain size fraction. In the map service these values are grouped and symbolised for ease of use. The sediment grain size fractions maps are intended for use at the same map scale as the original sediment grain size maps they are derived from: detailed 1:10 000 – 50 000, regional 1:100 000 – 250 000.

Grain size
SOSI-code
Grain size
SOSI-name
Mud %Sand %Gravel %Cobbles and
boulders %
Bedrock and compacted
sediments %
10Clay1000000
15Organic mud955000
20Mud955000
21Mud with sediment blocks
av sedimenter
8055100
30Sandy clay7524100
40Sandy mud7029100
50Silt928000
60Sandy silt6534100
70Clayey sand3465100
80Muddy sand2970100
90Silty sand1980100
95Fine sand594100
100Sand495100
105Coarse sand296200
110Gravelly mud8051500
115Gravelly sandy mud60251500
120Gravelly muddy sand25601500
130Gravelly sand4801600
140Muddy gravel30155500
150Muddy sandy gravel18275500
160Sandy gravel4415500
170Gravel459100
174Gravel and cobbles1945450
175Gravel, cobbles and boulders1535590
180Cobbles and boulders1115830
185Sand, gravel and cobbles13333330
190Sand and boulders3643300
205Mud/sand with cobbles/boulders30305350
206Mud, sand, gravel, cobbles and boulders303015250
210Cobbles/boulders covered by slam/sand20100700
215Sand, gravel, cobbles and boulders13029400
300Compacted sediments or sedimentary bedrock0000100
500Bioclastic material (corals, coral reef)252535150
1Thin or discontinuous sediment cover on bedrock.
Sediments with varying grain size.
665380
5Exposed bedrock0000100
0Unspecified-----
Last updated 21.03.2025
NGUMareano