pro finest_grid_containing_point, grid_info, point, grid_num, grid_level
; assumes grids are ordered from low to high resolution !
  grid_num   = -1
  grid_level = -1

  if N_elements(grid_info) lt 1 then return
  dim_grid_info = size(grid_info)
  num_of_grids  = dim_grid_info(1)
  
  i = num_of_grids
  REPEAT BEGIN
      i = i -1 
      FOUND = MIN((grid_info(i).left_edge  le point) and $
                  (grid_info(i).right_edge ge point))
  ENDREP UNTIL FOUND or i le 0

  IF FOUND THEN BEGIN
      grid_num   = grid_info(i).num
      grid_level = grid_info(i).level
  ENDIF
  
  RETURN
END