{
    "version": "1.0",
    "coordinate system":{"model":"cartesian"},
    "features":
    [
      {
        "model":"oceanic plate", "name":"Overriding Plate", 
        "coordinates":[[0,0],[0,1000e3],[1500e3,1000e3],[1600e3,350e3],[1500e3,0]],
        "temperature models":[{"model":"uniform", "temperature":293}],
        "composition models":[{"model":"uniform", "compositions":[0]}]
      }
    ]
  }