The lay of the land

    In writing about gardening on sloped properties recently I got curious about the topography of our area and started doing a little research. Why does the landscape look the way it does in Northwest Philadelphia?

    A large portion of South Philly is famously built on drained tidal wetlands, but up here it’s an entirely different story, full of ups and downs.

    Our region is made up of a series of ridges and valleys. The lowest valley is the Schuylkill River. The west side of the bank rises up to a ridge, then down to the Wissahickon Creek before rising to a second and higher ridge.

    Obeying the law of gravity, water will always collect at and move through the lowest point of a landscape, but inversely humans will often find the highest point on which to travel and settle. So it’s unsurprising that the two main arterial thoroughfares in our area are built on the two ridges, now much softened by centuries of development.

    Ridge and Germantown Avenues are among the oldest thoroughfares in Pennsylvania; they each may have been in use for a thousand or more years. By the time the Europeans came, these Native American trails which once linked the Delaware River as far west as Reading were already well established on what eventually became the major roadways in our part of the city.

    Traveling by water is one of the least arduous ways to progress through undeveloped territory. But besides the Schuylkill, we don’t have a navigable waterway in the Northwest. Taking the high ground would have been the next easiest route through the Pennsylvania forest. If you want to look at maps, and see how development evolved in relation to our topography, check out the Philly GeoCities website.

    And next time you’re stuck behind a bus in the purgatory of Ridge Avenue during rush hour, calm yourself by thinking about how your tires are on the same piece of ground that people have used to travel for a very long time. And for most of that time they probably weren’t moving any faster than you.

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