public static PolarRegion GenerateSouthPole(Boundary boundary)
{
var(top, bottom) = boundary.CutHorizontally(boundary.MinY + FilledRows);
var iceTiles = Landmass.Fill(bottom).LandTiles
.Union(Landmass.Generate(top, top.Area / 4).LandTiles);
return(new PolarRegion(iceTiles));
}