The boundaries for the zones enumerated in this title and ORS 227.310 and for those areas zoned and rezoned in accordance with ordinances enacted by the council and approved by the Major subsequent to the date of December 2, 1980, shall be as set forth by the engineering department on the map which is kept on file in City Hall; and that said map, subject to future amendment by the council, as recorded by the engineering department, is approved as the official zoning map of the city, December 2, 1980. (Ord. 4128 (part), 1981; Ord. 3380 (part), 1968).