The boundaries between districts are center lines of streets, alleys, railroad rights-of-way, streams, or such lines extended, or lines parallel thereto or concentric therewith, or property lines when proximate thereto, or may be lines otherwise indicated on the Zoning Map. When the Zoning Officer cannot definitely determine the location of a district boundary, he shall deny the application and the Zoning Hearing Board, upon appeal, shall interpret the location of the district boundary.