{
  "schema":1,
  "retrieved":"2026-10-02",
  "sources":[
    {"id":"cp-usgs-contours","publisher":"U.S. Geological Survey","title":"US Topo Cartographic Specifications — Map Symbol Guide","url":"https://www.usgs.gov/ngp-standards-and-specifications/us-topo-cartographic-specifications-map-symbol-guide","retrieved":"2026-10-02","supports":"Contours connect equal elevations; closer spacing indicates steeper slope; a contour interval is a height difference. Scale exercises use original arithmetic, not a copied map.","rights":"Factual reference only. No text passage, map, photograph or agency symbol copied."},
    {"id":"cp-nps-superposition","publisher":"National Park Service, Geologic Resources Division","title":"Geologic Principles—Superposition and Original Horizontality","url":"https://www.nps.gov/articles/geologic-principles-superposition-and-original-horizontality.htm","retrieved":"2026-10-02","supports":"Relative deposition order in an undisturbed sedimentary sequence. The exercise explicitly excludes overturned layers.","rights":"Factual reference only. No source diagram or photograph copied."},
    {"id":"cp-nps-gaps","publisher":"National Park Service","title":"Missing Time at Grand Canyon National Park","url":"https://www.nps.gov/articles/000/grcatime-missing-time.htm","retrieved":"2026-10-02","supports":"Gaps in a rock record may reflect erosion and/or nondeposition. Only this general principle is used; Grand Canyon chronology is not transferred to Bryce.","rights":"Factual reference only. No third-party photographs or diagrams copied."},
    {"id":"cp-nps-hoodoos","publisher":"National Park Service, Bryce Canyon National Park","title":"Hoodoos","url":"https://www.nps.gov/brca/learn/nature/hoodoos.htm","updated":"2021-09-04","retrieved":"2026-10-02","supports":"Bryce context: sediment deposition, weathering and erosion, frost wedging and formation of openings and pillars. No rate, age or dimensions are assigned to the invented diagrams.","rights":"Factual reference only. None of the page's individually credited media is reused."},
    {"id":"cp-nasa-sky","publisher":"NASA Goddard Space Flight Center","title":"The Sky Above Us","url":"https://pwg.gsfc.nasa.gov/stargaze/Ssky.htm","retrieved":"2026-10-02","supports":"A low Sun gives a long shadow from a vertical object. The two numerical shadow cases are original idealized trigonometry, not an ephemeris.","rights":"Factual reference only. No NASA media copied."},
    {"id":"cp-nasa-shadow-direction","publisher":"NASA Astronomy Picture of the Day","title":"Shuttle Plume Shadow Points to Moon","url":"https://apod.nasa.gov/apod/ap070603.html","published":"2007-06-03","retrieved":"2026-10-02","supports":"A shadow projects away from the Sun; the exercise uses only that geometric principle.","rights":"Factual reference only. The credited photograph is not copied or traced."},
    {"id":"cp-original","publisher":"BCC Canyon Puzzles pack","title":"Original teaching models and reasoning","url":"methods.html","created":"2026-10-02","supports":"Invented dimensions, coordinates, shapes, orthographic projections, arithmetic, evidence-card premises and answer derivations.","rights":"Original BCC teaching assets, authored for this pack; no third-party media or dataset. Not an agency product or measured reconstruction."}
  ]
}