{
 "about": "The record of this Plate: the facts it is drawn from, kept inside the work. Plain JSON; the artwork does not read it. CC0 1.0, no rights reserved.",
 "work": {"title": "North America", "series": "Plates", "artist": "Kenny Lienhard", "year": 2026, "plate": "4 of 52", "palette": "kaolin"},
 "plate": {"name": "North America", "code": "NA", "model": "PB2002 (Bird 2003)", "class": "major", "area_km2": 55431427, "centroid_lat_lon": [57.923, -86.078], "ocean_share": 0.5437, "land_share": 0.4563},
 "motion": {"frame": "no-net-rotation", "euler_pole_lat_lon": [-4.7537, -86.5198], "rotation_deg_per_million_years": 0.20609, "speed_mm_per_year_at_centroid": 20.36, "heading_deg_at_centroid": 270.5, "speed_range_mm_per_year": [7.03, 22.92], "the_artwork_drifts": "-20.36 mm a year along its cut, one frame of rock every 21974 years"},
 "cover": {"deep ocean": 0.2231, "shelf sea": 0.1248, "slope and ridge": 0.1206, "boreal forest": 0.094, "grassland": 0.0834, "sea ice": 0.0714, "forest": 0.0648, "tundra": 0.0629, "cropland": 0.044, "ice": 0.036, "lakes and rivers": 0.0288, "desert": 0.0183, "bare rock": 0.012, "rainforest": 0.0056, "ocean trench": 0.0038, "wetland": 0.0037, "towns": 0.0028},
 "palette_from": ["taiga", "grassland", "forest"],
 "era": {"name": "Last ice age", "what": "Ice sheets over North America", "arrives_years_before_2026": [33076, 26576], "leaves_years_before_2026": [19076, 6876], "account": "The past. The last ice age: the ice sheets of North America and Greenland were already growing when the timeline begins. They held their peak from 26,576 to 19,076 years ago, when ice covered about half of the plate’s land, then melted back until 6,876 years ago, when little more than today’s ice was left. The sea stood more than 100 metres lower, and a land bridge joined Alaska to Asia until about 11,000 years ago. Only the lines that stand for the ice change colour, all at once, and only across those spans.", "source": "Clark et al. 2009, Science 325:710; Dalton et al. 2020, Quaternary Science Reviews 234:106223"},
 "history": [{"years_ago": 4031000000, "range_years_ago": [4031000000, 4000000000], "what": "Rocks among the oldest known on Earth formed, now found in northern Canada.", "source": "Bowring and Williams 1999, Contributions to Mineralogy and Petrology 134:3, doi:10.1007/s004100050465"}, {"years_ago": 1840000000, "range_years_ago": [2000000000, 1800000000], "what": "Older continental blocks collided and welded together into the core of North America.", "source": "Hoffman 1988, Annual Review of Earth and Planetary Sciences 16:543, doi:10.1146/annurev.ea.16.050188.002551"}, {"years_ago": 201520000, "range_years_ago": [201600000, 200900000], "what": "Huge lava floods erupted as Pangaea began to break apart, at the time of the end-Triassic mass extinction.", "source": "Blackburn et al. 2013, Science 340:941, doi:10.1126/science.1234204"}, {"years_ago": 55500000, "range_years_ago": [56500000, 55200000], "what": "Greenland, which rides on this plate, split from Europe and the northeast Atlantic Ocean began to open.", "source": "Storey, Duncan and Swisher 2007, Science 316:587, doi:10.1126/science.1135274"}, {"years_ago": 30000000, "range_years_ago": [31500000, 28500000], "what": "The Pacific plate first reached this plate's western edge, and the San Andreas fault system began to grow.", "source": "Atwater 1970, GSA Bulletin 81:3513, doi:10.1130/0016-7606(1970)81[3513:IOPTFT]2.0.CO;2"}, {"years_ago": 6300000, "range_years_ago": [6500000, 6300000], "what": "The Gulf of California began to open, and Baja California moved over to the Pacific plate.", "source": "Oskin and Stock 2003, Geology 31:23, doi:10.1130/0091-7613(2003)031<0023:MISWPB>2.0.CO;2"}],
 "outline_lon_lat": [[[-47.69, 15.96], [-46.77, 15.45], [-46.39, 18.42], [-45.02, 22.96], [-44.92, 23.65], [-46.48, 23.92], [-42.73, 30.07], [-42.14, 29.97], [-41.43, 31.24], [-39.59, 33.07], [-39.4, 33.77], [-37.8, 33.5], [-36.37, 35.28], [-34.75, 35.01], [-33.59, 36.74], [-32.28, 37.39], [-31.52, 37.28], [-29.77, 39.4], [-29.3, 40.7], [-29.32, 43.08], [-28.52, 43.77], [-27.51, 46.2], [-27.46, 47.66], [-28.56, 49.64], [-29.87, 50.79], [-30.03, 52.03], [-35.14, 52.71], [-35.45, 53.55], [-35.12, 54.31], [-35.49, 54.33], [-35.34, 55.0], [-34.22, 56.75], [-33.59, 56.87], [-33.5, 57.26], [-29.03, 60.34], [-24.01, 63.36], [-21.3, 64.07], [-19.24, 63.86], [-17.37, 64.74], [-16.51, 66.2], [-19.1, 67.06], [-17.83, 68.4], [-17.15, 68.86], [-16.49, 68.81], [-13.89, 70.82], [-12.25, 70.56], [-11.36, 71.05], [-12.36, 71.25], [-11.37, 71.77], [-7.37, 71.12], [-5.7, 71.54], [-2.94, 71.5], [7.39, 73.25], [9.2, 73.98], [7.6, 75.73], [7.78, 78.23], [3.43, 79.03], [4.39, 79.53], [-2.34, 80.37], [-1.68, 80.62], [-3.36, 80.79], [-2.41, 81.13], [-4.64, 81.37], [-3.91, 81.62], [-5.03, 81.91], [-3.7, 82.33], [-7.21, 82.87], [4.03, 84.6], [19.28, 85.68], [58.02, 86.79], [66.54, 86.65], [69.75, 86.47], [68.21, 86.31], [99.44, 84.91], [112.84, 83.67], [119.1, 82.09], [125.19, 78.99], [125.68, 78.13], [127.18, 77.23], [128.96, 74.94], [138.52, 69.04], [139.38, 67.91], [143.73, 66.32], [144.93, 65.29], [153.95, 61.72], [163.34, 61.24], [170.74, 61.74], [169.03, 60.29], [164.93, 58.9], [162.59, 56.42], [164.07, 55.21], [171.85, 52.03], [180.0, 50.5], [180.0, 90.0], [-180.0, 90.0], [-180.0, 50.5], [-177.09, 50.5], [-171.63, 51.17], [-156.14, 54.53], [-148.26, 57.35], [-145.76, 59.27], [-144.32, 59.92], [-142.41, 60.47], [-140.13, 60.38], [-137.11, 58.44], [-132.71, 53.13], [-128.03, 49.78], [-127.82, 49.08], [-126.73, 48.29], [-125.52, 45.47], [-125.31, 41.65], [-124.74, 40.31], [-124.42, 40.31], [-122.38, 37.53], [-119.94, 35.45], [-115.6, 33.24], [-115.33, 32.42], [-114.12, 31.36], [-114.44, 31.1], [-113.81, 30.31], [-113.97, 29.65], [-111.38, 27.5], [-111.51, 26.93], [-109.81, 25.56], [-110.01, 25.34], [-108.36, 23.61], [-108.65, 23.24], [-108.01, 22.99], [-108.68, 21.96], [-106.89, 21.8], [-105.95, 19.4], [-103.2, 17.62], [-98.59, 15.77], [-95.8, 15.28], [-90.9, 12.58], [-90.81, 13.39], [-88.88, 15.62], [-84.25, 17.34], [-81.62, 17.8], [-81.75, 18.86], [-73.24, 20.29], [-68.85, 19.59], [-63.36, 19.69], [-61.55, 18.96], [-59.95, 19.45], [-58.31, 19.19], [-56.8, 18.69], [-54.85, 17.31], [-50.47, 15.87], [-47.69, 15.96]]],
 "sources": ["Plate outlines and motion: Bird, P. (2003). An updated digital model of plate boundaries. Geochemistry, Geophysics, Geosystems 4(3), 1027, doi:10.1029/2001GC000252. No-net-rotation frame computed from PB2002 alone.", "What covers each plate: ESA CCI Land Cover and Water Bodies, NOAA ETOPO 2022, Koppen-Geiger climate maps, NSIDC Sea Ice Index, on a 1 arc-minute grid."],
 "engine_sha256": "a7fbc03acc0fc9ba343881bb88ddaf2b7564564d8bc9cbed16e75e47e01fb3f2"
}