Contour Maps: Visualizing 3-dimensions

In the lower left is a spot elevation/benchmark at the railroad tracks on Broadway road behind Tempe High School, 1,161 feet above sea level. To the right is a spot elevation/benchmark at the corner of Broadway and Rural, 1,172 feet above sea level. This is an 11-foot change in elevation (z-value) in about 1.25 miles, a very small slope indeed. ................
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