Annotation: Richardson Island Stratigraphy

Annotated stratigraphy of lowest Richardson Island archaeological deposits.

Richardson Island is a remarkable archaeological site in southern Haida Gwaii.  When it was occupied, sea levels were about 10 metres higher than today, and rising.  Then, sea levels stopped rising and occupation continued.  We have dates ranging from 10,500 cal BP to 2900 cal BP (calendar years before present).  However, the early part of the record includes the most impressive stratigraphy.  The shoreline configuration at that time likely included a supra-tidal marine berm feature, which would have had a flattish top and have been well-drained and probably vegetation free: a perfect place to camp.  Occasional storms or even tsunamis would build this berm in the winter, and with rising sea levels the berm was “pushed uphill” so to speak.  The berm-building process would have involved sudden dumps of sorted pea-gravel onto the occupation layers at the site, sealing and preserving them.  Overall, though, the site is in a well-protected location, at least relative to the enormously dynamic winter sea conditions of Haida Gwaii.

In the picture above, the thin black layers are the intensely cultural tops of the occupation layers, a sort of A-horizon.  The thick red wedge in the middle is a lightly cultural massive dump of gravel, or several dumps separated only narrowly time.  Notice how it tapers to the left.  This is the inland extent of it – it feathers off according to distance from the high-tide line.  The picture below includes a schematic showing how the complex marine and terrestrial site formation produces unusual, highly-distinctive layering at this site.

You can see how the stratigraphy is deep but represents only a few hundred years.  We are able to pick apart this stratigraphy in a way which allows sub-decadal resolution of human behaviour, 10,000 years ago.

Findings of interest from Richardson Island  include a series of hearth features in layers 21-23 and below, each of which has a different assemblage of calcine fish bone.  There are also interesting trends in use of stone tools and exploitation of raw material for stone tools.  We interpret the site as a fall-winter base camp, with prominent activities being salmon harvesting and processing, and hunting for bears in their wintertime lairs in nearby karstic landscape on Moresby Island.

Schematic and overview of Richardson Island site formation and locale. Click for higher resolution.

One response to “Annotation: Richardson Island Stratigraphy

  1. I find this amazing! – Will you be there again this summer? I’d love to come and visit. And you’ll have to stop by here so I can show you some cool things I’ve found near Copper Bay (Kasta).
    Just out of curiosity, partially because of archaeological interest, and partially because of where I live and the recent earthquakes and tsunami evacuations, I was wondering about archaeological evidence of tsunamis. Anything discernible? I’ve always thought it would be cool to be able to tie in archaeological evidence of tsunamis on this side of the Pacific, with Japanese records of earthquakes on their side…
    However, my main concern now is whether they are actually feasible here or not.
    On a side note, anyone want to buy a lovely house on Haida Gwaii? 😉

    Like

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