Scale on Map—Determination by Commission. Where the property is indicated on a zoning map or maps as acreage and not subdivided into lots and blocks, or where the zone boundary lines are not approximately street, alley or lot lines, the zone boundary lines on the zoning map or maps shall be determined by scaled contained on the map or maps, and where uncertainty exists, the zone boundary line shall be determined by the Planning Commission. In the event property shown as acreage on the zoning map or maps has been or is subsequently subdivided into lots or blocks by a duly recorded subdivision map or record of survey and the lot and block arrangement does not conform to that anticipated when the zone boundaries were established or property is resubdivided by a duly recorded subdivision map or record of survey into a different arrangement of lots and blocks than shown on the zone map, the Planning Commission, after notice to the owners of the property affected thereby, may interpret the zone maps and make minor readjustments in the zone boundaries in such a way as to carry out the intent and purpose of these regulations and conform to the street, block and lot layout on the ground. The interpretations shall be by written decision, and thereafter the copies of the zoning maps in the Planning Commission Office shall be changed to conform thereto.