The scale for most of the maps were obtained by a natural scale indicator and shown by sub-brackets; i.e. 1: 1 000 000. In some instances no latitude lines were drawn on the maps and no other scale indications were available so therefore an estimated scale was obtained by measuring where the latitude lines would be drawn on the map and then the natural scale indicator used to measure an approximate scale and that scale placed in parenthesis; ie. scale is not indicated (about 1:1 000 000).