Botanical Remains
February 18, 2019
By Alexandra Glass & Jeanne Ward, RPA
Due to the Chesapeake climate, fluctuations in humidity and temperature often cause organic materials to decompose quickly leaving little for archaeologists to analyze. However, preservation can occur when organic material becomes carbonized. Carbonization of seeds, wood, and plant fragments occur in environments where the temperature is very high, but oxygen is low. Carbonization preserves organic material by maintaining the shape and morphological characteristics of the object while eliminating material destructive micro-organisms feed on.
figure 1. alex glass conducting flotation by placing soil samples into the large tank. carbonized organic material floats to the surface and are collected in the second tank. water then flows to the third tank, which contains a pump, to be recirculated back to the first tank.
At Cloverfields, AAHA staff have been working to collect preserved plant remains through a process known as flotation so researchers can learn about the types of plant foods residents consumed and the environment surrounding Cloverfields. Flotation separates carbonized material from other artifacts and soil by using their differing densities. As soil is poured into the tank, the lighter carbonized remains float to the surface, while heavier soil and artifacts sink (Fig. 1). This process gently collects fragile carbon so it can be analyzed.
A wood-lined cellar, Feature 341 (Fig. 2), identified in the concrete addition to the rear of the back building and which contained artifacts dating to the mid-18th century provided abundant ashy soil samples to process for collecting botanical remains. The pit was located in front of a fireplace and the ashy soils within likely represent hearth sweepings. While there is still much analysis waiting to be completed on the collected carbonized remains, bread wheat grains (Triticum aestivum), corn kernel and cob (Zea mays), Plum (c.f. Prunus domestica), Apple or Pear (Malus sp.), Squash (Cucurbita sp.) and Peach pit (Prunus persica) have already been identified (Fig. 3). In addition to carbonized seeds and pits, charred fragments of food are also present. These fragments appear amorphous with an almost foam-like texture, and could be evidence of bread, porridge or starchy vegetable remains. The use of imaging from a Scanning Electron Microscope (SEM) can be used to identify which plants compose the amorphous fragments.
figure 2. feature 341, a wood-lined cellar located in the concrete addition. the ash fill is visible abutting the brick rubble as well as in the profile at the bottom of the photo.
Historic documents pertaining to Cloverfields list a variety of plant resources both in storage and growing in fields near the main house. William Hemsley’s 1738 inventory lists over 464 bushels of corn and other inventories mention bushels of rye, wheat, barley and beans. Although orchards are not explicitly noted, the presence of a cider press and stills alongside apple seeds implies that apple orchards were likely maintained nearby.
Sorting through the flotation materials will take time, but it is already clear from the variety of fruit and vegetable remains thus far identified, that further analysis will provide information on the types of plants both being cultivated and growing wild at Cloverfields.
figure 3. sample of carbonized fruit seeds from feature 341. left to right: plum (prunus domestica), apple or pear (malus sp.), squash (cucurbita sp.) 1 cm scale.