This post looks back to one of the specialized activities that we did at the outset of the Plymouth field school this year.

We Came, We Saw, We Cored
By Anya Gruber

At the beginning of field school, a small group of professors and students (led by Dr. Heather Trigg) set out to core the sediments at Brewster Gardens, a public park on the waterfront, just down the street from Cole’s Hill. Since we’ve never excavated in this area, we were interested in coring so we could get an idea of what the stratigraphy of the soil looks like under the sod. It seemed like the best way to peek into the stratigraphy since coring works well in wet, marshy soil, just like the banks of the stream in Brewster Gardens. Wet deposits can also trap and preserve pollen, so we also wanted to find a place to take a core to look at changes in the local environment over time.

There are several ways to go about taking a core sample; you can use a hand corer, which is a short metal tube that you push into the ground by hand and then pull out, trapping in soil that can then be pushed out and analyzed for sediment, artifacts, and other clues into the chronology of soil layers in a particular area. This method can be difficult in Plymouth, though, because there are so many rocks that block the core from smoothly entering the soil. The alternate coring method uses the same basic ideas, but with bigger, heavier equipment. At Brewster Gardens, we used a full-size vibracorer, which has many more moving parts to it: a 10 ft. metal tripod, a motorized head powered by two heavy marine batteries, several-meters-long plastic and aluminum tubes, and all sorts of screws and different kinds of tape to keep everything in place. The heavy head generates vibrations that help push the coring tubes into the sediments.

Before we could turn on the machine and take the sample, we had to choose exact locations to core. We wanted a marshy but not super soggy, relatively flat surface far away from large tree roots and utility lines. We decided on three different locations: behind the Pilgrim Maiden fountain, between the stream and the benches, and next to the rock wall. The head hangs from the tripod, which was hoisted up by a pulley. The tube (the plastic one broke the first time we used it, so we switched to using only aluminum) was screwed onto a platform at the bottom of the base and carefully lowered into place, exactly where we want it to enter the ground. We then switched the machine on, and with some help from Blaine Borden, Professor Landon, and Professor Trigg pulling the head down, the tube goes straight into the ground. Luckily, we did not have much trouble with the tube getting blocked by the ubiquitous Plymouth rocks. However, the core was driven into the ground so tightly that we had to turn the vibracorer on again to shake it up so we could pull the tube out again.
We took four samples in total, one of which we kept in the tube to bring back to the lab, and the other three we looked at in the field. The one we kept will be taken out and analyzed in the fall; I’m hoping there’s some seventeenth-century pollen in there! The three we looked at in the field appeared to be mostly fill, from when the whole area was filled in to create land, as Brewster Park had been a tidal pool when the Pilgrims arrived in 1620 – but we did find a few artifacts, including a red rhyolite flake and some redware. There were also different layers of sediments in the core, including dark, organic silts and yellow coarse sand. The process of filling this area, which transformed it from a tidal inlet to a park is one of the landscape changes that we are interested in documenting. Additionally, since the process of filling can cap, bury, and preserve older layers, areas where there are buried ground surfaces could be archaeologically interesting.