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Cutting Edge Tundra. Episode 2: Extremely Ultimate Alaskan Palaeoecology

August 9, 2015

It has now been three weeks since the ‘Extremely Ultimate Alaskan Palaeoecology’ team posted any news. Seeing as we’ll all be leaving here in just over a week, the time seems ripe for a second instalment. When we left you last we had just finished collecting our huge tins of mud on what was, thankfully, the only stormy day of the field season thus far. Since then the weather has picked up, especially this past week, and I have been able to get on with a lot more science stuff. Here come the highlights.

DSCF5121

Edouard pondering another GIS problem, and my tin of unsampled peat.

Sampling tools

My sampling toolkit.

With my tins of peat safely back at camp the first task was to sub-sample them. Sub-sampling involves cutting consecutive 1 cm sections of peat/sediment from the larger sample (1-2 cm, 2-3 cm, 3-4 cm etc.) until the entire profile has been chopped up and placed into wee bags. Unfortunately, this being Extremely Ultimate Alaskan Palaeoecology, I was not collecting the little 20 ml samples I would typically collect, I has taking huge 2 litre samples of peat! Normally I would use a pair of tweezers and a small scalpel and scissors, but that wouldn’t cut the mustard this time. Anticipating this eventuality I brought with me a 30 cm pair of ‘culinary’ tweezers (the stuff you can buy on Amazon), a Buck hunting knife, a Petzl climber’s knife and a palette knife. Thank God I did! What is usually just a mind numbingly boring task also became one of endurance with the huge samples of peat that I was dissecting. The knives and tweezers helped me through it.

 

Sphagnum moss ready for to be submitted for dating.

Sphagnum moss ready for to be submitted for dating.

With the sub-sampling complete I turned my attention to determining the age of the sediment. This involved me looking down a microscope (science) to collect plant remains from the 1 cm sample from base of the profile. Specifically I was searching for Sphagnum moss remains. This isn’t just because I have a penchant for Sphagnum moss, although I will admit it is beautiful; Sphagnum moss is a short-lived plant which makes it perfect for obtaining reliable radiocarbon dates. After a day staring down the microscope a petri dish sorting Sphagnum out of a variety of plant remains – which is a lot more fun than it sounds – I packaged my sample up and shipped it off to the lab in Florida. The results are in, but you’ll have to wait until the end to find out how old the peat is!

 

Bibles with strategically placed plants

Bibles with strategically placed plants

Aside from emptying Véro’s insect traps and periods of sieving and a little digging here and there I have also been working on another project. Although this has been a little more sedate than my first one it is definitely in keeping with the ‘extreme’ theme. My other project is to build a reference collection of the flowering plants that grow in the Y-K delta region which I will use to help identify plant remains in both archaeological and palaeoecological samples. This may not sound particularly extreme, but it involves collecting and identifying specimens of over 250 plants in four weeks, or over 60 different plants each week! Needless to say I am not hitting my target, but I have made some good progress. Thus far I have managed to gather seeds, leaves and, where applicable, the woody parts of over 50 different species. Already this work is proving invaluable and has helped me to put names to a number of the plants that I have been finding in the archaeological deposits. With a bit of luck maybe I’ll reach 100 by the time we leave!

 

The beginnings of my plant reference collection.

The beginnings of my plant reference collection.

So now you are all up to speed on the world of Extremely Ultimate Alaskan Palaeoecology, except for the results of the radiocarbon dating. I’m sure you’re all very excited to know the outcome. I know I was. In fact I have to admit I was more than a little nervous that it was not going to be old enough and that we would have to find another place to sample. I needed have worried.

 

The peat at the bottom of our hole is around 1,700 years old, this means the tundra around Quinhagak is probably not much older than Jesus!

 

And it also means we don’t have to dig, thaw and sample another hole!

 

Paul

2 Comments leave one →
  1. Marjorie permalink
    August 9, 2015 16:37

    Could you say more about what the age of the tundra means in any regard, be it possible dates of human occupancy, geological events that had to happen before the tundra formed, average age of other tundra regions in Alaska?
    I realize the blog is more aimed at people with training in your disciplines, but I became fascinated by the project, and would love to learn more.
    Thanks very much!

    • August 15, 2015 06:01

      Hi Marjorie,

      The age of the tundra isn’t all that interesting per say, at least from an archaeological perspective.

      From a geological perspective the tundra, at around 2000 years old, is very young and similar to dates from slightly further north. However, it is much much younger than the other areas of peat in Alaska. Further south around the Anchorage area I believe that basal dates (for when the peat began to form) are nearer to 15,000 years.

      Neverthless it was important for us to know the age of peat (the soil) beneath the tundra for our past climate study. The peat (soil beneath the tundra) is composed of plants that previously were growing on the surface of the tundra and this peat grows and grows with time as plants die and become incorporated into the peat. The plant remains then become waterlogged are preserved in the peat, much like the artefacts at the site. By digging down into this peat and examining the plant remains that are preserved we are able to reconstruct the past environments. We therefore want to know how old the peat (tundra) is so that we know how far back in time we can reconstruct the climate.

      I hope that helps. I’m pretty tired though so this response may be completely incomprehensible!

      P

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