What a geological province is

A region is not a polygon

Lithoen stores a geological region and a drawing of where it is as two different records, and this is the architectural commitment of the whole phase. A craton is not a polygon. A polygon is one published opinion about where a craton is, drawn at one scale, by one group, from one kind of evidence, on one date — and another group’s polygon may put the edge somewhere else.^[1]

Embedding one outline in the entity would assert, permanently and silently, that the outline is the region. It would also leave nowhere to put the second outline. So a region carries as many spatial representations as there are interpretations Lithoen has read, each with its own source, its own scale, its own statement of how certain the edge is, and its own epistemic status.^[1,2]

The kinds, and why they are values rather than types

Craton, shield, platform, terrane, orogenic belt, sedimentary basin, volcanic arc, large igneous province, passive margin, rift province, mobile belt, geological domain. These are recorded as a controlled value on one entity type rather than as thirteen types, because they share every field and every relation, they overlap, and one piece of crust is legitimately several of them at different scales.^[1]

Where a source delimits a region without classifying it, the honest value is geological domain. A guess dressed as a classification is worse than an admission that the source did not say.^[1]

What a region record does not contain

No country. Geology does not obey political borders, and a province that crosses six of them is not six provinces. Lithoen records a continental or oceanic realm for navigation and nothing else.^[1]

No assessment. A region record says what is there and how that is known. It does not say what might be there, and there is a validator whose job is to keep it that way.^[1]

Commonly misunderstood