Wednesday, May 7, 2014

The 1814 Fortification Ditch in Patterson Park

I was out in Patterson Park to meet with some of the project's financial backers and check in on the fieldwork. It was a gorgeous day.

In our third attempt to dig a trench across the 1814 fortification ditch we finally got the profile we were looking for. (This is the same trench I worked in on Saturday.) In our first two trenches we could see what might have been the 1814 ditch, if we squinted right and waved our hands for effect. But honestly if we hadn't known what we were looking for we would not have described the soils in either place as a backfilled ditch. But this third profile is exactly what we were hoping to see. It's hard to make out in these pictures because of the angle, made necessary by the narrow trench. But if you enlarge the pictures above and look closely you can see five distinct layers in the soil. At the top, labeled A in the second picture, is dark grayish brown topsoil. Below that is a mixed-up layer with numerous rocks (B), which is landscaping fill put down in the early 1900s when the Olmstead Brothers beautified the park. We have found both of these layers everywhere we have dug. Beneath the landscaping fill is the 1814 ditch. The top layer of in the ditch (C) is a mix of the landscaping fill with the older trench fill. Beneath that is a layer of sand (D) that washed into the ditch in the decades after it was abandoned, untouched since before the Civil War. And below that (E) is the natural subsoil.

Since we feel like we have a good grasp on the soils we are looking for, we have started trying to trace the trench across the landscape using smaller holes. Using a bucket auger (top picture above) you can extract a narrow column of soil, which you can lay out next to a measuring tape (bottom picture) to get an approximate idea of the stratigraphy below the surface. We tried our first group of auger tests 75 feet from our last trench, and we think we identified the fortification ditch there, along the same line. But 150 feet down the line (45 m) we did not find it, so we suspect that it has curved. Fortunately we still have a few more days to sort this out.

I celebrate completion of the third trench across the ditch, with its beautiful profile.

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