cf50a5b8_GPlates_Data_Manual_Table_3__Properties_Table_Used_In
[Property] leftPlate [Optionality] Optional, required for dynamic polygon closure [Description] Refers to the plate on the "left" side of the plate boundary. Strictly speaking, this is an optional feature with the purpose of , however GPlates does make use of it in the dynamic polygon closure algorithm. Note that in this context, "left" specifically refers to the left hand side from the perspective of an observer travelling through the geometry of the object. This means "left" is entirely dependent on the order in which the points that comprise the geometry of the plate boundary were digitised. That is to say, if the plate boundary was digitised with the first point being in the South, and the last point being to the North, then the "left" is the plate to the West. If on the other hand, the exact same plate boundary were digitised with the first point being in the North, and the last point in the South, then the "left" plate is to the East. See diagram below. image::leftRight.png If there is more than one plate to the left of the boundary, it may be necessary for the use of dynamic polygon closure to break the boundary into pieces. Otherwise, the choice of which plate to use is arbitrary, however, the plate which shares the larger area of the boundary at the present time may be the most descriptive plate to use. [Used In] 
ContinentalRift MidOceanRidge Transform SubductionZone OrogenicBelt FractureZone PassiveContinentalBoundary
GPlates Data Manual
Used In