Today’s work on the Mazotos was a natural progression of the work performed yesterday. To continue on the lines that had been tagged and anchored for the trench-based progressive excavation, all teams of divers were sent down to the wreck with three main objectives:
1) To confirm the presence of identification tags on the artefacts (consisting mostly of amphorae)
2) To report any amphorae in their assigned zone with a missing or damaged tag
3) To record the area using pictures and video for use in verifying line placement, condition of artefacts, condition of tags, familiarization with the team’s assigned area
4) To practice with post-fieldwork tagging, organization, and reporting.
While these objectives may seem quite simple indeed, the first three at 43 meters beneath the sea become a daunting order. The two main restrictions in productivity come from limited time on the Mazotos site itself, and nitrogen narcosis.
The limited time stems from the heavy nitrogen loading incurred at such an extreme location – all divers can only spend 20 minutes per day on the wreck!
The bottom time for most of today’s teams was used as follows:
- 1 minute: Initial descent and safety checks
- 3 minutes: Main descent to Mazotos wreck
- 10 minutes: Artefact tag verification, marking on slates, cleaning
- 4 minutes: Photographic and video recording of the site
- 1 minute: Equipment clean-up and safety checks
- 1 minute: Navigation to ascent line
During those 10 minutes of verification on the wreck, our teams were able to do some amazing things. We positively identified 23 amphorae in our zone (including several photogrammetric reference control points), as well as gathering accurate photo-survey data that fine-tuned the charted position of the bow trench line to be much more accurate! As a bonus, we were even to identify the location of a formerly ‘’lost’’ amphorae, setting us up for success to tag it tomorrow.
Many lessons were learned by our team from the post-fieldwork study in today’s class. The most important of these was the necessity of taking pictures of artefacts from not just varied angles, but also varied distances (and overhead at 2 meters,) to allow for a better sense of location and context when identifying mystery finds. With continuing practice, we look forward to using our imagery while learning photogrammetry to allow an even greater sense of awareness and appreciation of the site, while simultaneously saving valuable time.
So far, my favourite part of this expedition has been the opportunity to work on an actual archaeological site, contributing key data to an ongoing study that will directly affect future studies and publications. The sense of satisfaction on a project this large and involved, with adventurers and experts from around the globe, only grows stronger as the days go by.
The next couple weeks hold some very exciting training. In particular, I’m really looking forward to the ROV and photogrammetry applications. ROVs are essentially a remotely-controlled underwater craft with video cameras that transmit to the ship, allowing the topside team to monitor and support the dive team much more directly. This greatly increases both safety and situational awareness for everyone, while allowing the divers to focus more on the important tasks. Photogrammetry allows rapid survey of an area using advanced processing to convert pictures with perspective differences into useful 3D models of the surveyed region. This saves the dive team several weeks of work, sometimes more, while also increasing accuracy significantly. That’s a winning combination, and I can’t wait to apply it soon!
Written by Christopher Drew