Authors: Xander Berry, Attila Lukács, and Vanessa Sullivan
The Flinders University Maritime Archaeology Program’s field school has been hard at work for the past week, SCUBA diving up to three times a day, to record the Leven Lass shipwreck site off of Phillip Island, Victoria. Built in 1839 in Scotland, Leven Lass was a brig used primarily for timber trade. The ship ran aground off Westernport Bay in 1854 and has been waiting for archaeologists to tell it’s story ever since!
Although this is not Flinders University’s first time to the site; it is a first for many of the field school participants, including the members of the field school’s Green Team: Xander Berry, Attila Lukács, and Vanessa Sullivan (supervised by Kurt Bennett and Maddy Fowler). As a means to develop students understanding of the skill-set required for underwater archaeological survey, a myriad of archaeology methods have been utilised throughout the course of the field school, including mapping, photography, and geophysics.
An integral component of any archaeological survey, whether it is above or below the water, is the establishment of datum points. These datum points allow for measurements of artefacts and structures to be made accurately throughout a site. Essentially, the datum point (or datum network) acts as building blocks for the archaeological site survey and provides points of reference at the site.
The re-establishment of a datum network at the Leven Lass shipwreck site was one of the many tasks students have undertaken as a part of the shipwreck survey. A number of datum points were already put into place during the 2012 field season however, the measurements of each segment needed to be re-measured to account for any changes that likely occurred at the site since 2012. The identification of the datum points from the 2012 season proved to be a beneficial way for students to introduce themselves to the extent and layout of the Leven Lass site.
Mapping the Wreck:
Once measurements for the datum network had been completed, measurements of the ship structure and associated artefacts could begin. The shipwreck is situated in a dynamic environment making something as simple as holding a tape measure extremely difficult. To make the measurement process easier on the team, a baseline was set up between two of the datum points: D and I. The placement of the baseline was selected due to its proximity to exposed hull timbers.
Two methods of data point collection have been utilised during Green Team’s survey: baseline/offset and trilateration. The baseline/offset system uses a right angle between a baseline and the point to measure, where trilateration relies on measurements from two or more points. At present over 200 measurements have been collected. The points all represent features on the ship structure or of an artefact and can be used to assist in the creation of a detailed site plan. The site plan is a work in progress… Xander is entering data into the Site Recorder program as this blog is being written!
In addition, detailed and small-scale mapping has been completed for areas along the baseline that have parts of the ship structure that are more intricate. These small-scale drawings are going to be overlain on the Leven Lass site plan and perhaps even aligned with scaled photographs of the site and ship components.
Photographing the Site:
Photography has been used throughout the surveying process to document the shipwreck site as well as the surveying process at the site. Dr. Jonathan Benjamin, with Flinders University, gave a lecture to students on underwater photography so that the students had some basic knowledge on camera settings and photographic methods. Photography has played a crucial role in the data collection process at the Leven Lass site: photographs of individual artefacts, photographs along the baseline, and photographs of the surveying process have been taken on a daily basis.
Attila has worked on combining several photos that were taken of the ship’s wooden planking to create a photomosaic. This photomosaic has been extremely useful in assessing the artefact back on dry land and being able to look at the piece as a whole, rather than just what the visibility in the water allows for. It is a team goal to be able to create such detailed images for other artefacts as well, however that is all dependent upon visibility and, of course, time.
Where are we?:
Although the datum network allows the team to understand where they are working within the site, it does not provide an understanding of the shipwreck’s location in relation to the rest of the world. For this reason, Green Team took GPS points from the shoreline as well as four of the datum points and a feature on the shipwreck site. The Leven Lass GPS points were collected by floating a buoy from the datum points, to the surface, and collecting the GPS data at the buoy. Having the GPS points enables the team to geo-reference the site and overlay the data onto existing nautical charts and maps.
Life at a field school has not only been about work below the waves; it has also included a series of lectures on the various components of maritime archaeology, use of computer programs to log and record the data collected at the site, and hours spent trying to make sense of the ever chancing Leven Lass archaeological site. Green Team still has a couple more days of hard work ahead of us, and with each passing day more and more of the Leven Lass site becomes visible, bringing new information to the surface with each dive!
Well done to all the bloggers,
Good to know what you are up to at the site. Sounds like you are all going great above and below the water.