May I Date Your Sand?

Our current sites are awesome, but honestly our bone is rubbish. Apparently, thousands of years of water slowly percolating through sand managed to leach out of the bone anything useful when it comes to dating, namely collagen.

Ken hard at work smacking the sampling tubes into place

Ken hard at work smacking the sampling tubes into place

Normally we like to have multiple sources back us up when determining how old an occupation is. For example, some nice projectile points and paired with some AMS radiocarbon dates. The projectile points alone might be enough to give a strong indication but people of the past could be hoarders too, or be equally drawn to shiny things like we are, and so we see much older artifacts in more recent contexts which messes things up a bit. Gophers, gophers are also kind of bastards when it comes to burrowing and moving things around. Nothing like excavating down a meter only to find a bottle cap in the bottom of a gopher hole to make you question everything you just did.

Tubes in place!

Tubes in place!

And, as mentioned in a previous post (An Unexpected Occupation) our projectile points are vague and out bones are rather problematic – very fragile and lacking in collagen.

Detailed recording of where all the samples come from

Detailed recording of where all the samples come from

In the end we gave up on bone and looked for alternatives; in the end we decided on attempting to date our sand. Optically stimulated luminescence (OSL) is a method of dating minerals instead of organics, basically it tells us the last time the sand was exposed to sunlight. It doesn’t give us as precise a date at the carbon dating but it’ll get us a close range.

These tests are too big!

These tests are too big!

I only vaguely understand the science behind it (I can point to a good paper on it though if you want to learn more, or just cheat and go to Wikipedia), so we called in an expert from the Athabasca University, Ken Munyikwa to help us take the samples and get them sent off to Scotland for analysis. The trick to sampling is to make sure you don’t ruin your sample by exposing it to any sunlight (well that and evaluating things like saturation levels, stratigraphy, context, etc.). But all the sampling went well, now to be patient for the next 5 months until we get the results back!

Ah, these ones are just right!

Ah, these ones are just right!

Looks like killer gophers destroyed our beautiful walls

Looks like killer gophers destroyed our beautiful walls

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