Analysis of present production and estimated future requirements shows that available reserves in existing quarry areas will be depleted around the year 2010. Ownership of mineral deposits does not bestow statutory rights for working and legislative restraints exist in several Acts of Parliament. The effect of these on construction materials resources is indicated. The Hills Face Zone is a significant and important producer of extractive minerals, particularly crushed aggregate. Unusual geological features of the quartzite and dolomite beds in the zone provide the best resource potential for aggregates in the Ranges. More than half of the existing aggregate and clay quarries in the zone are located out of sight from the plains and reconnaissance geological mapping indicates that extensive resources exist in similarly concealed areas. Development of such deposits is compatible with the principle of the Hills Fact Zone, defined in the Metropolitan Development Plan. Reserves of materials for future generations should now be proved and set aside to ensure their availability. This responsibility is seen as a function of Government. Utilization of resources nearest to Adelaide has had economic advantages in the past. A geological survey of alternative sources is in progress and will be followed by a comparative economic and environmental study of the effects of developing such deposits. Revision of the Metropolitan Development Plan in respect to construction materials is recommended to extend Extractive Industry zones and establish resource reserves over these deposits most suitable for future development.