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LITHOEN

Tectonic plate

Juan de Fuca Plate

A small remnant of the once-vast Farallon Plate, still spreading offshore and still subducting beneath North America along the Cascadia margin, where it feeds the Cascade arc.

Classification

plate class
minor

How this is mapped

2 published representations of where Juan de Fuca Plate is. Each is one interpretation, by one identified source, at one scale — not the shape of the thing itself.

  • Tectonic model geometry

    Polygon · 56 positionspreferred for publication

    Geometry that exists because a model defines it — a rigid-plate outline, a zone where a model declares itself inapplicable. It is a property of the model, and changes when the model is revised. It is present-day geometry from a present-day model; a palaeogeographic reconstruction is a different thing and Lithoen does not hold one.

    The Juan de Fuca Plate as outlined in model PB2002 (Bird, 2003). This is the model’s boundary, not a mapped geological contact: it is where a rigid-plate model puts the edge of a plate, and Bird’s own documentation states that coordinates are given to a precision of about 60 m while "accuracy never equals precision". Where deformation is distributed rather than confined to a line, the model marks the region as an orogen and the outline there is a convenience.

    Boundary certainty
    InterpretedThe boundary was placed by a geologist reading evidence: mapping, geophysics, geochronology, structure. It is reproducible from that evidence and it is an interpretation of it. Most geological boundaries are this.
    Status of this geometry
    modelledThe status of the geometry, which need not match the status of what the entity’s claims assert.
    Dataset
    PB2002 plates, boundaries and orogens as GeoJSON (fraxen/tectonicplates)Plate model PB2002 from Bird (2003), doi:10.1029/2001GC000252; GIS conversion by Hugo Ahlenius, Nordpil, ODC-By 1.0.

    What was done to this geometry

    • By Lithoen — Douglas–Peucker, 96 positions to 56
    • By Lithoen — Coordinates rounded to 4 decimal places, about 11 m of longitude at the equator.
    • Before it reached Lithoen — Bird (2003) digitised the boundary curves from published sources at varying scales; the model is a compilation, not a single survey.
    • Before it reached Lithoen — The GIS conversion (Ahlenius, ODC-By 1.0) split segments spanning the -180/180 meridian and moved them, as its README states. Four plates therefore arrive as multi-part geometries.
  • Boundary

    LineString · 53 positions

    A line delimiting or separating things — a plate boundary, a suture, a mapped contact. A boundary is not an extent: it says where the edge runs, not what lies on either side.

    Juan de Fuca–North American boundary as drawn in model PB2002 (Bird, 2003), from source segments JF\NA. The Cascadia margin, where the small Juan de Fuca Plate — a surviving fragment of the once-vast Farallon Plate — descends beneath North America and feeds the Cascade arc. The model labels these segments as subduction. Digitised by: by Peter Bird, 1999.

    Boundary certainty
    InterpretedThe boundary was placed by a geologist reading evidence: mapping, geophysics, geochronology, structure. It is reproducible from that evidence and it is an interpretation of it. Most geological boundaries are this.
    Status of this geometry
    modelledThe status of the geometry, which need not match the status of what the entity’s claims assert.
    Dataset
    PB2002 plates, boundaries and orogens as GeoJSON (fraxen/tectonicplates)Plate model PB2002 from Bird (2003), doi:10.1029/2001GC000252; GIS conversion by Hugo Ahlenius, Nordpil, ODC-By 1.0.

    What was done to this geometry

    • By Lithoen — Coordinates rounded to 4 decimal places, about 11 m of longitude at the equator.
    • Before it reached Lithoen — Bird (2003) compiled these curves from published sources at varying scales, crediting each segment to its own source; those credits are carried in the caption of every record.
    • Before it reached Lithoen — The GIS conversion (Ahlenius, ODC-By 1.0) split segments spanning the -180/180 meridian and moved them, as its README states.

In the knowledge graph

Record last updated 2026-09-07. Corrections follow the published corrections policy; superseded claims are retained, never silently edited.