We have started into our 5th test unit today, after a disappointing previous two units. These units were very light on artifacts and ballast, but as we often say in archaeology, negative evidence is still evidence. These two nearly empty units tell us much about spatial distribution and orientation of the site. We now have a much better understanding of the limits and boundaries of how the site rests. The positive news is though, unit 5 is turning out to be very rich in ballast, with some other artifacts coming out as well. We’ve only scratched the surface of this unit, but it is very promising at providing some answers to our most fundamental research questions. We had our first small find today: a piece of glass, almost certainly within the context of the ballast, although it’s connection through some other intrusive means is possible. Before we say any more about the glass though, it needs to be examined by some of our laboratory staff for second opinions. We’ll push on tomorrow and hopefully have some additional interesting finds to report on.
One of the most common questions I receive as an underwater archaeologist, even by some terrestrial archaeologists, is just how we go about digging underwater. I thought I would take some time to discuss this. The two most common tools we use to remove sediments are airlifts or induction dredges. They both work more or less the same way, vacuuming sediments from the site. Airlifts are the simplest of these devices. An air compressor pumps air through a hose and to a PVC pipe, releasing it near the lowest end, held by a diver. The air then travels up the pipe, which is held nearly vertically, thereby creating suction. An induction dredge, which we are using due to the shallow depth of our site, pumps water at a very high speed to a connection on a pipe, shooting it to the back of the pipe and creating suction from the intake end. While it is possible to simply suck up sediment, excavation must be done very carefully to ensure that we don’t lose any data or artifacts through careless methods. To achieve this, the dredge is always held above the surface and the dredge is fed by the diver, either by hand fanning, or the method Troy Nowak demonstrates in the video below. It’s all very simple, but painstaking. Everything we do is recorded by drawing, photography, measuing, and other necessary notes, ensuring that everything we do is preserved for other researchers to retrace our steps, which is perhaps the most important thing to keep in mind when planning and carrying out fieldwork.