tectonic context
A coordinate can be precise to sixty metres and still be in the wrong place. The author of the plate model Lithoen uses says so himself, and everything in the spatial architecture follows from taking him seriously.
About: Pacific Plate
The documentation for model PB2002 states that every point is given to six significant digits, so that round-off error in position does not exceed sixty metres, and then adds a sentence that ought to be printed on every geological map ever made: "however, accuracy never equals precision."[1]
Precision is a property of the number. Accuracy is a property of the knowledge. A boundary stored to six decimal places is not better known than one stored to two; it is only written down more elaborately, and a map that can be enlarged without limit invites the reader to mistake resolution for evidence.[1]
Lithoen stores a boundary certainty on every geometry, from a fixed vocabulary. DEFINED means the boundary is where it is because a definition puts it there. INTERPRETED means a geologist placed it by reading evidence. APPROXIMATE means the position is known only within a distance much larger than the line width. GRADATIONAL means there is no line at all, only one domain grading into another. CONCEALED means it is buried and has never been seen. DISPUTED means published workers place it in materially different positions.[1]
The Stillwater Complex offers a worked example. It lies, the USGS chromite model says, along a persistent high-gradient gravity zone related to the faulted front of the Beartooth Range. That structure is known from a gravity gradient — which means the line is inferred from a potential field, not walked, and no amount of zooming will improve it.[1]
Bird states that a single class cannot always be specified for an entire plate boundary curve, or even for an entire segment, because the class changes with local changes in the azimuth of the boundary. Lithoen therefore labels a boundary as subduction only where the source does, and classifies no further. Where a plate pair has both kinds of segment, the corpus stores two records rather than choosing one label for the whole.[1,2]
Often said
“A boundary drawn on a map is where the geology changes.”
What the evidence supports
It may be. It may also be inferred from geophysics beneath cover, drawn by convention through a gradation, or required by a model. The map cannot tell you which, which is why each Lithoen geometry states its boundary certainty in words.
Supporting records: boundary-may-be-interpretive · map-position-not-certainty
Often said
“More decimal places means a better-known position.”
What the evidence supports
The source of Lithoen’s plate geometry gives six significant digits and states in the same paragraph that accuracy never equals precision.
Supporting records: map-position-not-certainty
Bracketed references link to the structured entity records whose claims support each paragraph. Last updated 2026-09-07.