Tag Archives: Intertidal

Fieldwork Picture of the Day 7

Excavations at Collison Bay, 2006

Excavations at Collison Bay, 2006

This is another intertidal dig – the Collison Bay site, which shares a lot of similarities with Kilgii Gwaay.  Both sites date to about 9450 C14 years ago and contain buried deposits in primary context below the modern beach.  While Kilgii Gwaay contains a rich organic assemblage, Collison Bay does not, though there is evidence for a brown palaeosol at varyiong depths.  In and around that palaeosol are numerous pristine lithics: stones tools and flakes that are sharp and clearly have not een rolled on a beach.  One of the striking things about these two sites is they show how a major event like a marine transgression can nonetheless leave intact cultural deposits.  We suspect that much of this has to do with the local topography.  Ideally, a bedrock rock rim allows for a small lagoon to form, creating an interlude of very low wave energy between when sea level rises over the site and when the full weight of waves can start to act on the surrounding shore.  By the time the waves are able to penetrate, the archaeological materials are already several metres below low tide which affords quite a lot of protection.

As with Kilgii Gwaay, working in the intertidal zone poses certain challenges, such as having only a six hour window to work.  In the case of Collison Bay, we compounded the issue by timing the project for when the best tides were in the middle of the night, which meant getting up at midnight and working to dawn in some cases (though we did have some good daytime digging as well).  In this picture you can see we are using electric lights run off a generator while Cynthia does the hard work down on the beach; this is probably around 2.00 in the morning.

Fieldwork Picture of the Day 2

Daryl watching the tide flow at Kilgii Gwaay.

Daryl watching the tide flow at Kilgii Gwaay.

Another fieldwork picture form the archives. This shows Daryl watching the tide come into our units at Kilgii Gwaay (map) – this is Operation 8a and 8b, if I recall, from 2001.  At first we tried to completely dig out a unit during a single tide window but this was quite rushed, and limiting.  So we tried lining the units with bubblewrap and then just before the tide reached them we would pump them full of water (hose into a bucket in the bottom of the unit) to provide outwards pressure on the sidewalls and to prevent erosion of the unit edge.  This actually worked really well: for the most part the units survived the tidal change and could be pumped out with no trouble.