The boundaries between zoning districts are, unless otherwise indicated, either the center lines of streets, railroad rights-of-way or other such lines extended or approximately parallel or perpendicular thereto. Where figures are shown on the Zoning Map between a street and a district boundary line, they indicate that the district boundary line runs parallel to the street line at a distance equivalent to the number of feet so indicated. In instances where a district boundary line is a property line, the distances shown will be those measured from the property line to the nearest identifiable landmark, such as a street, railroad, etc., at each end of the property line. In these cases, the boundary line is coincidental with the property line existing at the time this chapter is adopted. In case of uncertainty as to the true location of a district boundary line, the Zoning Officer shall make the initial determination thereof. Such determination shall be appealable to the Zoning Hearing Board.