Battling the Water Table

Perhaps we can go into building underground houses after this project

Perhaps we can go into building underground houses after this project

I mentioned previously the surprise occupation located 185cm below the surface, it turned out to be a rather good occupation level with ample bones and artifacts. Our problems arose as we got a bit deeper into it and encountered the water table – unlucky for us there happens to be a high water table in the area. So, now we not only had to worry about creating shoring that would prevent us from being covered in sand at any given moment but also how to draw the water away from our active units.

It's just a bit of water, no big deal.

It’s just a bit of water, no big deal.

In the end, our solution was sump pumps. We had four pumps running around the clock to keep the water low enough that we could excavate through the occupation level; we started this area at the end of winter and as spring thaw hit us we had to try and dig the pumps even deeper to keep on top of the water situation (we had to quickly, but still properly, excavate sump pump holes in areas of low artifact returns). We also discovered that water-logged sand is also rather prone to giving out suddenly – quite aggravating when you’re trying to keep the walls looking good for photographs, profile drawing and site visitors (no one wants to be accused of having sloppy walls, no one).

13-246~2491We only recovered 5 projectile points from this occupation level – not great but not terrible. They’re a bit mysterious though, they don’t really fit with the type of points we were expecting to find at that depth. We were expecting thicker, chunkier points, but these ones are relatively thin and well-made. They look like they should be Late Period points but that doesn’t fit with the order of the occupations we have represented on our site. So, at the moment our best guess is that they are intermediate points from the transition of Early to Middle Prehistoric – which is exciting because that means they’re quite old indeed (7 – 9,000 years old).13-246~2971

Normally, we do radiocardon dating of the bone to back-up our estimation of the date based on the projectile points. Our sneaky low occupation had plenty of bone but the water table got one up on us this time. The bone looked fantastic as you exposed it from the damp, organic-rich sediment but as soon as you tried to remove it from the ground it would crumble into a pile of tiny fragments. Through much painstakingly slow work we managed to get some of the bone out in relatively one piece and sent it off to the labs in Florida.

It looked so good until we tried to take it out.

It looked so good until we tried to take it out.

Sadly, all our efforts were in vain. The constant movement of water in the area had leached all of the collagen out of the bones, leaving nothing for the lab to extract and test for us. We sent them almost 10 samples and each one came back with the same disappointing outcome. Not to be discouraged, we were set upon the idea of doing OSL (optically stimulated luminescence) dating. This method of dating involves taking samples of sand from deep within our profiles and using science-magic (ok it’s real science I just don’t know all the specifics of how it works) they analyze the last time the sand was exposed to sunlight.

Lining up the OSL samples.

Lining up the OSL samples.

Taking the samples took an afternoon, waiting for the lab in Scotland to get us some dates took about 5 months longer. Our preliminary look at the dates supports our Early to Middle transition deduction with the date range being 6780 – 8700 years BP. We still need to do some further analysis and make sure everything matches up like it should between all the records, but we’re excited and this is definitely the oldest Alberta site I’ve worked on thus far.

Return to Civilization

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One shovel test – down to 85 cm.

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One excavation block were we dug 8 units, most of the microblades came from the corner they’re working in

The last couple of days in the Yukon were good; we finished up our excavation units, refilled them and had a slacker day around camp before flying back to Whitehorse. We didn’t find anything else terribly exciting, but that’s the way it goes sometimes.

Most of the cultural material (points and artefacts) came out of the top 30 to 40 cm of sediment but one of our shovel tests had a random bone at 75 cm below surface – just one perfectly intact tibia….thus we had to take all of our shovel tests and excavation units down that deep, or even deeper (some went to a meter). This seemed a bit drastic but at least four of our units had nothing until the 75 cm point and then we found 1 bone in each unit, most curious and annoying – I feel like it was just one random animal that decided to die all the way across our site.

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Al’s expert hands at work

The last day at the camp was fun though, well aside from tackling the mountain of dirty field clothes. We were given permission, and some quads, to go gold panning for the afternoon! Apparently this is called sniping – you are allowed to pan for gold without a claim in order to see if there is anything in the area. Luckily, we had Al, a toothless older gentleman mechanic on the mountain who used to have his own gold claim and business, show us which sediment we should be panning and how to do it. As with all things, he made it look quick and easy. It involves a lot of swirling and continually dipping the pan in and out of the river, when I tried I felt like I wIMG_4240as floating any gold I might have had downstream, I also couldn’t figure out how he magically made all of his rocks disappear from the pan. In the end, we did find some tiny flakes which I now have in a preposterously large ziplock bag, I also brought home a sandwich-sized bag of sediment that needs to be panned still, hopefully my fortune is in that bag!

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The moccasin

After that excitement, we flew back to Whitehorse and stayed the night. Before our last plane ride home we went to the archaeology branches’ main repository for an early morning visit. We took along some of the cool stuff we had found and the woman was able to help us pin down some tentative dates for when the tools would have been used (as early as 12,000 BP!), and then she showed off some of the amazing things that have been found in the Yukon, especially on the ice patches. Normally we don’t see a lot of organic material because it breaks down too quickly but the ice fields have freeze-dried a lot of wooden and leather items. They also have the oldest moccasin there, they have arrowheads still in their shafts, spear shafts, a spear point made from an antler tine – so many cool things. They also had some dinosaur bones (I know we don’t do dinos but I still think they’re awesome), and they have an impressive collection of megafauna bones – mammoth bones!

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An antler that would have had microblades inserted into the cut along the bottom edge (x-rays show that there are still broken pieces inside), there is also a unique character carved onto the top edge – thought to help identify who owned which weapon

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A broken point, sinew and wooden shaft

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Mammoth bones!

All the Pretty Things

As promised, here are some of the pretty, shiny things that we found. We also found a ton of flakes – the garbage that would have been left over after making fine tools like these (but they’re less pretty to look at), as well as a fair amount of burnt or calcine bone (animal). Animal bone was often burned at high temperatures in order to make the bones brittle. This, in turn, made it easier to get out the marrow which was a valuable source of nutrients. We were really hoping to come across the hearth or boiling pit where they were doing this but alas, we did not stumble upon it this time. But by looking at the concentrations of finds, you start to get a feel for how the area was divided up  – projectile points were being made or retouched (resharpened) near the end of the promontory, while the cooking would have taken place further back from the edge where the landform widens out a bit.  It’s still a fragmented picture of what was going on at the site, but it is a start.

(you can click on the pics to find out a bit of info on them)