Why do sections of some estuaries appear terraced?
In some cases the soundings were recorded to the nearest fathom. A fathom is an interval of 6 feet. While most of an area was recorded in feet or meters, a section of that area that was recorded in fathoms will look much more coarse when it has been triangulated because all of the information between the full fathom intervals has been omitted in the original data set. When the grids have been given values by the triangulated file, these areas will appear evenly spaced and colored and will stand out from the rest of the gridded data.
