Our third guest blog features the Centre for Sustainable Archaeology at McMaster University in Hamilton, ON. This post was written by Jennifer Walton, a third year anthropology student at McMaster, and Research Assistant at Sustainable Archaeology. The blog features her experience using the Centre's materials analysis equipment to examine "microfacts" recovered from the McMaster field school at the Nursery Site (AhGx-8) this past spring.
From the Field to the Lab: Artifacts and “Microfacts” from the McMaster Archaeological Field School
By: Jennifer Walton, Honours Anthropology (III), Research Assistant, Centre for Sustainable Archaeology at McMaster Innovation Park
This spring I had the opportunity to attend the McMaster University archaeological field school held at the Nursery Site (AhGx-8) in Cootes Paradise within the Royal Botanical Gardens. The site dates from approximately 3000 years ago and was also used as a farmstead during the historic era. During the course of the excavation, we were responsible for conducting two different types of sub-surface surveys to find the boundaries of the site and to evaluate the differences between traditional test-pitting used in cultural resource management, and a finer resolution method. Each student took standard test-pit samples using a shovel alongside bucket-auger samples to analyze the variability in field survey methods. Understanding the variability in the recovery of artifacts using different techniques is important because of the history of plowing at the site, and the fragmented nature of the artifacts we recovered. Test-pit sediment was screened in the field, following the guidelines set by the Ministry of Culture. The auger samples were later wet-screened at the Centre for Sustainable Archaeology at McMaster Innovation Park.
Auger sampling has been used at the Nursery Site since the 2010 field school. Since the site has been a plough zone for over 50 years, the Nursery Site had experienced heavy disturbances, resulting in the fragmentation of many of the artifacts. Auger sampling is useful in this context because it retains the entire sediment sample and the finer screening method allows for the collection of smaller artifacts, often resulting in more artifacts per litre of soil compared to traditional test pitting. The boundaries of a site should show a decrease in artifact density as one moves away from the central area of the site, therefore augering is potentially a more effective way of finding the outer limits of the activity area, especially in highly disturbed areas.
The bucket-auger sampling method uses a hand held device (7.5cm bucket-auger) that is twisted into the ground below the sub-soil to extract an intact sediment sample. All of the sediment is retained, and once in the Sustainable Archaeology lab, each auger sample is washed through 2mm mesh, dried, and the sediment fraction >2mm is examined beneath a stereomicroscope. The sediment from the test pits, in contrast, is screened in the field through 1/8 inch mesh and artifacts are picked in the field. It is the difference in these screening methods, in association with the methods used to identify artifacts that accounts for the variance in artifact recovery.
In the lab the auger samples were wet-screened, and the remaining fraction was viewed under a Zeiss V8 microscope at 10 X magnification to distinguish if the materials were, in fact “micro” artifacts. Many research questions can be answered from the analysis of these samples, such as artifact densities and types of artifacts found in specific areas of the site or throughout the site as a whole. Site boundaries may also be estimated and further insight into disturbance levels may be gained. The results from the auger samples have shown new insights into the artifact densities as well as the extreme fragmentation of the artifacts, especially calcined bone, ceramics and tertiary debitage. Using this survey method and the resources at the Centre for Sustainable Archaeology has allowed us to identify new areas of the site which can be excavated in future field seasons.
|Examples of the "microartifacts" found in the auger samples, using a Zeiss V.16 axiozoom telecentric microscope at 20 X magnification. From left to right: historic era ceramic; tertiary debitage; calcined bone; pre-contact ceramic)|