With sea levels rising by at least 120m globally at the end of the last ice age, conventional archaeological wisdom has been that sites on ancient coastlines are now deeply drowned. As is so often the case, conventional wisdom is over-simplified. The B.C. coast is a good example, since the effect of ice weighting in some places counterbalanced the lower sea levels, meaning significant chunks of the coastal plain and paleo-coastlines were never-drowned. Nonetheless, the underwater environment off the west coast doubtless contains thousands of early-period archaeological sites. Looking on land is more convenient, easier, cheaper, and allows one to breathe air – all good things. But looking underwater has some attractions too: methodological challenges, modelling issues, thinking about human life on a shrinking landmass, and a ridiculous amount of media coverage. The last is particularly important to University Administrators. Anyway, this month’s ASBC Victoria talk (poster, PDF) is on a project from a couple of years back which focused on attempting to find a particular kind of archaeological site on the sea floor: drowned fish weirs, especially rock wall ones, starting from the premise that such sites, which are often substantial in size, should be confined to stream channels and might be directly visible to sidescan sonar. For more information on the talk, click below.
The picture above shows a sidescan sonar image of a braided stream channel now 55 metres below modern sea level. As you can see, this terrestrial landscape feature is well-preserved despite having the sea rise over top of it about 11,000 years ago. A stone-wall fish weir projecting into one of these channels should show up fairly clearly as a line of bright spots denoting reflective rock boulders. The total area in the image above is about the size of a soccer field.
From local archaeological sites such as Gaadu Din 1 and 2, we know people were on this now-drowned landscape by 12,500 years ago at least, and that salmon were there a thousand years earlier, at least. So it is not a stretch to postulate that those people, Ancestral Haida, may have constructed fish weirs.
Anyway, I could write much more but the talk will focus on the premise for the project, the methods used, and some interesting targets (not only potential weirs) on the seafloor for further investigation, by someone, sometime.
If you have more questions and can’t make the talk, then feel free to comment below.
The talk is Tuesday, Nov 21st , 7:30 Cornett A129, UVic Campus, Victoria, and is free and open to the public. Link to the poster (PDF).