Fieldwork is the time when archaeologists get to head out to a site and get their hands dirty. It can be the most fun and exciting part of being an archaeologist, but there is also a lot tedious and detail-oriented work involved as well. The main purpose of fieldwork is to collect and record archaeological data. It is not just excavation. Fieldwork can also involve surveying and mapping an archaeological site. Most fieldwork is done seasonally. Archaeologists prefer to gather data when it is warm and dry, leaving the cold winter months for work back in the lab.
Site Survey: What do we have here?
In order to locate and assess the size and scope of a potential archaeological site, archaeologists do a site survey. Depending on the objective, site surveys can range in level of detail, amount of documentation and even methodology. The goal of archaeological survey is to be able to produce a basic document on the site detailing the type of site it is, its geographical boundary and the level of disturbance within that boundary. A comprehensive site survey is an important first step in order to understand the nature of the archaeological site and how best to approach any further investigations.
A surface, or pedestrian, survey is often the first thing that is done on a new site. Archaeologists look for above-ground evidence of an archaeological deposit. Artifacts and features, along with mounds, extra green spots in a lawn or a suspicious depressions can all be clues indicating a hidden archaeology. Copious notes, measurements and photos are taken. Artifacts are recorded and either collected or left in place, depending on the project protocol.
Archaeologists use sampling techniques as a way to find out more about what lies beneath the surface of an archaeological site. Through sampling, archaeologists can verify whether an area contains any archaeological remains, check out soil stratigraphy and identify site disturbances. A common form of sampling involves placing shovel probes or test excavation units across a potential or known site, giving archaeologists a snapshot of what lies beneath the ground. Soil probes, augurs and geophysical instruments can also be used to "see" underground. These techniques can provide lots of data on the location, size, type and layout of an archaeological site — vital information for determining if and where to excavate.
Careful and thorough surveying of a site can save archaeologists time and money. It can also help prevent needless excavation — and, as a result, destruction — of archaeological sites. Where possible, archaeologists always like to leave a portion of the site intact "in perpetuity," as research questions and technology are constantly evolving. Sampling strategies allow researchers to get good archaeological data while at the same time leaving some of the site intact for the next generation of archaeologists.
Excavation: Can You Dig It?
As with any science, archaeology operates under a controlled environment whenever possible. Archaeological excavation can range from a small 50x50 cm test pit, to a 1x1 meter unit, to a trench spanning several feet. Archaeologists try to work in increments that are easiest for mapping and recording. Whenever archaeological material is removed from the ground, it is important to document it in such a way that it can essentially be recreated later.
Units are the most common excavation layout. A square is an easy format to work with and in. Archaeologists excavate by removing dirt from a unit in controlled levels. These levels can follow the stratigraphy of the soil or can be based on an arbitrary measurement, such as 10 centimeter layers. This allows archaeologists keep their data organized so later they can figure out what was found where and why.
As dirt is removed from a unit, it is put through a screen, so that even the smallest of artifacts can be recovered. While a chunk of ceramic or a glass bottle may be obvious in the soil, tiny things like beads, flakes or lead shot may easily be overlooked. Regardless of the size of the objects, it is important to recover as much as we can from an archaeological deposit.
A Picture (or Map) is Worth 1,000 Words
Archaeology is a finite resource. When you excavate, you destroy. So it is absolutely crucial to record as much information as possible during the excavation process. From the site to the specific artifact, all aspects of the project must be carefully recorded. Site maps depict the entire archaeological site and show where any excavation took place. Artifacts are collected in labeled bags that designate the specific unit and layer where they were found. Soil stratigraphy is captured through side wall profile drawings and features or artifacts can be sketched or mapped too. Even the smallest detail can turn into important data later on.
In addition to hand-drawn maps, archaeologists often use survey instruments such as a total station transit or a GPS (Global Positioning System) unit to gather precise geographical information of the area and excavation. All forms of data collected can then be integrated into GIS (Geographic Information System) software to create 3-dimensional site maps that can help sort and analyze the huge amount of data recovered in a typical excavation. The result is a map with layers of information that can highlight distribution patterns or spatial relationships within the archaeology.