Nearly every printed topographic map I’ve ever looked at has the contour interval, otherwise known as the distance between contour lines, listed in the legend. Depending on the scale of the map, the contour interval ranges from 1 foot to hundreds of feet between each successive contour line. The contour interval allows the map reader to instantly know the relative steepness & flatness of the topography in the map at one quick glance. Because of this crucial information, a topographic map is considered incomplete when it does not disclose this information to the reader.
Enter the Terrain feature of Google Maps. Released to the public in November of 2007, the contour lines were subsequently added in April of 2008. I hadn’t really given the feature much use until last week when I was planning my weekend excursion to the Shenandoah mountains. I was trying to figure out the altitude variation on my friends property by finding where their property line started & ended and calculating the elevation change. Since their property lies on the side of a mountain, I wanted to know the altitude at the bottom of the property and the altitude of the highest portion of the property, and subtract the difference to find the total elevation variance.
What I found out instead was that Terrain function of Google Maps was lacking the contour interval declaration in the legend. As with all their maps, the lower left-hand corner showed the units of distance on the map, but was missing the topographical information provided by the contour interval declaration.