Topographic Road Maps: Fairfax VA

Barry A. Klinger
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Why A Topographic Road Map?

Most road maps do not include topography, and those that do are usually difficult to read. A topographic map is extremely useful for biking, because elevation changes can make cyclists do a lot more work. Sometimes a cyclist may want to take a longer route if it avoids a large hill. Topography can also be important to pedestrians with mobility issues.

Understanding the lay of the land can be intrinsically interesting. Even people very familiar with an area may think of the topography as a chaotic and random set of hills and valleys. Seeing the pattern on the map can reveal simplifying patterns.

Fairfax City & County Near George Mason University

A map centered on George Mason University (see below) is useful for students and staff at the school. The map shows that elevations in the city of Fairfax and surrounding areas are dominated by a series of three neighboring ridges, each trending [very] approximately north-south. Within a mile or so, elevations can change by as much as 200 feet from hilltop to valley bottom.

We can learn the patterns of topography from the map. It makes clear the importance of water in shaping the land, because the branching shape of the valleys indicate that they are defined by streams. A good rule of thumb for northern Virginia is that if you go to the bottom of a hill, you are probably near a stream. The branching of the streams complicates the shape of the main ridges, each of which has mini-ridges protruding from them.

The neighborhood just north of Mason is the local high point. It happens to be where Fairfax City Hall stands. Fairfax County Courts and other municipal buildings are also close to the highest elevations.

Some roads, such as Rte 123 south of Mason campus, tend to follow along the top of ridge lines. Others, such as Braddock Rd (rt 620), plunge up and down several hills and valleys.

Neighborhood Map - Northeast of Campus

The previous map only showed major roads, but close-up maps (like the one shown below) include all side streets. Note also the smaller contour interval (20 feet), which helps show more topographic detail. Campus slopes upward from the south, with the highest points near the center of the academic area within Patriot Circle. North of campus, Blenheim Road (formerly Old Lee Highway), follows a ridge line for a while but then plunges down at least 60 feet before reaching Arlington Blvd.

Between Blenheim Road and the Beltway (I-495), Arlington Blvd is like a roller coaster, climbing in and out of at least 4 stream valleys branching off from the larger stream to its south.

The Webmap

Working with GGS faculty member Armita Kar and me, ASSIP high school student Kevin Hasani created a web version of these maps: Fairfax Topographic Accessibility Map. Besides allowing users to change the map's location and scale, it includes other layers such as bicycle paths.

Topographic Context of Fairfax

Why is Fairfax City and Mason main campus on high ground? What is around it? The map below shows topography for the wider region. The hills of Fairfax are bounded by the Potomac River flowing around it in the north and the east. The high ground is part of a series of low ridges that stretch southward into Prince William County and northward into Maryland. Thus Fairfax is also bordered by a wide, long valley to the west. Finally, a tributory of the Potomac called the Occoquan River carves a valley to the south and marks the border between Fairfax and Prince William counties.

To the west is a sharper ridge stretching from Warrenton past Leesburg and into Maryland. It is interrupted in a few places by the Potomac and various tributaries. To the west of that are a series of higher ridges, including the one that forms the dramatic setting of Harpers Ferry, WV. The same ridges continues off the west side of the map as the mountain range of Shenandoah National Park.