Archaeology 101: Shovel Test Pit Survey
Whenever Campus Archaeology is alerted of a construction project on campus, we typically conduct what is called an archaeological survey to determine if there are any potential archaeological sites in the area. This is important because it gives us the opportunity to quickly examine a large area, and then do more detailed archaeological excavations if we are able to determine that possible sites exist. There are a number of different types of survey that are used, each depending on what equipment is available and what the type of environment being surveyed. We are using two survey techniques while we search for the location of the Weather Bureau: Geophysical Survey and Shovel Test Pit Survey. This post will discuss the latter.
Shovel Test Pits, or STPs, are a way for archaeologists to cover a large area quickly. STPs are minimally invasive, meaning that they do not disturb a lot of ground, yet provide enough data for us to determine how viable an area is for further archaeological testing. The STP is a shovel-by-shovel width hole dug straight into the ground. The dirt is sifted, and artifacts are collected and their type and quantity is recorded on a map. We then examine the map for areas where their are significant artifact clusters, and identify those areas as potential archaeological sites that need to be further examined.
Let’s use our survey at the Weather Bureau as an example. Our first step was to establish a grid and pace off the location of where the STPs would go. Because we are in a small area, and were hoping to identify a building location, we decided to put STPs every 5 meters. In larger areas, these STPs would have been spaced at 10 or 15 meters. After this was settled, the STPs were excavated, artifact counts were recorded, and plotted on the map. STPs with significant concentrations are referred to as “positive” while ones with no or few artifacts are “negative”.
When we were finished, definite clusters of positive STPs began to emerge on the map near the north west corner. At this point, it is customary to excavate “radials”. These are additional STPs that are dug to the north, south, east, and west of each positive STPs, giving us a more refined picture of how these clusters are delineated. If a positive STP is surrounded by negative radials, than it is typically assumed there is no site there. In this case, these radials ended up being positive, indicating that there was significant human activity occurring in this space. Because these items were primarily bricks and nails, it is assumed that this was most likely the location of a building, probably the Weather Bureau.
The next step would be to do further testing to determine how much of the building is still intact. It is quite possible that this was just brick rubble and fill from the building’s demolition, not intact features or foundations. Without STP survey, however, we would not have been able to identify where to begin these excavations, making this a critical piece of archaeological methodology to understand.