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Prehistoric Human Response to Climate Change 2010

Dear Claude:

That's so neat that you saw an erupting volcano on one of your first days in the field! It makes me wonder, though: Your landscape is so steep and your volcanoes so active (compared to Finland and Canada, where your team also does archaeology) that why don't the ancient sites get covered up by volcanic ash? How is it that there are any left? yours, Michael Wing

Sun, 07/18/2010 - 00:32

Claude Larson

Hi Michael,I will admit seeing a volcano actually erupting is a very cool
experience. The landscape is very steep because Kamchatka is at the
edge of a subduction zone with the Pacific Ridge. So many of the
mountains are being pushed up from the plate tectonics. Of course, the
shifting plates are also creating the numerous volcanoes we have here.
They are so steep because the lave that erupts from them is generally
very thick and does not run all the way down the sides sometimes. The
major eruptions that create the tephra layers are hundreds and thousands
of years old. So the sites do get buried. In fact when we dig for them
we have to dig more than a meter in depth. So, unlike Finland where the
sites are close to the surface, we not only have to scale steep slopes,
we have to carry big shovels to use when we get to the dig site.
thanks for asking.
Claude

Tue, 07/20/2010 - 10:54

Michael Wing

I see - the tephra layers must be so even that the depressions in the ground don't get filled in - otherwise you wouldn't be able to find them today. yours, Mike

Wed, 07/21/2010 - 02:32

Claude Larson

Hi Mike,Generally the layers fall pretty evenly on the ground, thus making
finding the depressions easier for us. They can become uneven due to
wind or if they fall on a layer of snow they will sift with the snow
melt. We see this sometimes during an excavation, there will be a
thinner or thicker layer of tephra in one place or another. It can
sometimes be missing in small sections too.
thanks for the question,
Claude