Sec. 555. General Plan - Procedures for Adoption. Procedures pertaining to the preparation, consideration, adoption and amendment of the General Plan, or any of its elements or parts, shall be prescribed by ordinance, subject to the requirements of this section. (a) Amendment in Whole or in Part. The General Plan may be amended in its entirety, by subject elements or parts of subject elements, or by geographic areas, provided that the part or area involved has significant social, economic or physical identity. (b) Initiation of Amendments. The Council, the City Planning Commission or the Director of Planning may propose amendments to the General Plan. The Director of Planning shall make a report and recommendation on all proposed amendments. Prior to Council action, the proposed amendment shall be referred to the City Planning Commission for its recommendation and then to the Mayor for his or her recommendation. (c) Commission and Mayoral Recommendations. The City Planning Commission shall hold a public hearing before making any recommendation on a proposed amendment to the General Plan and shall act within the time specified by ordinance. If the Commission recommends disapproval of an amendment initiated by the Commission, it shall report its decision to the Council and Mayor. After the Commission recommends approval of an amendment initiated by the Commission, or takes action concerning an amendment initiated by the Director or the Council, the Commission shall forward its recommendation to the Mayor. The Mayor shall have 30 days to forward his or her recommendation to the Council regarding the proposed amendment to the General Plan. If either the City Planning Commission or the Mayor does not act within the time specified, the Commission or Mayor shall be deemed to have recommended approval of the proposed amendment. (d) Council Action. The Council shall conduct a public hearing before taking action on a proposed amendment to the General Plan. If the Council proposes any modification to the amendment approved by the City Planning Commission, that proposed modification shall be referred to the City Planning Commission and the Mayor for their recommendations.