Results from the geochemical analysis

Finally, the results of the soil analyses are tripping in! In autumn, I sent quite a lot of soil from the longhouse site in Kvarnbo to Sweden to be analysed for plant macrofossils as well as for different geochemical properties of the soil; and, now, I have received the report from Samuel Eriksson from the Environmental Archaeology Laboratory at Umeå University. Samuel analysed 10 samples, ca 20 gram each, for parameters such as MS, MS550, CitP, CitPOI and LOI 😀 (you just got to love the abbreviations instead of lengthy explanations, don’t you!) – In any case, MS stands for magnetic susceptibility of soil, which reflects the presence of magnetic iron-oxide minerals resulting by burning, meaning that fire increases the magnetic susceptibility of soil. MS values are for the “natural” magnetic susceptibility of the soil in the original sample, while MS5500 values stand for the results after heating the original samples at 550 °C in the laboratory. Laboratory-induced heating is executed since the magnetic susceptibility of soil may be naturally high or low without connection to anthropogenic processes and laboratory ignition is kind of reference to the original samples. Simply put – this analysis tries to find out if the site/feature has been affected by fire. CitP and CitPOI are related to phosphates – both the organic and inorganic fractions, where CitPOI gives a reading of the sum of inorganic and organic phosphate. LOI stands for the amount of soil organic matter. Basically, these analyses try to find out if lots of organic waste has been deposited on the site or in a certain feature. And, below, you can see the results:

markkemi

What does these “pillars” say? Well, one of my main questions while sending in the soil for the geochemical analysis was to find out which features have been affected by fire and which haven’t, in order to, among other things, separate different features from one another and find out if the longhouse has been burned or not. And the answer is in the MS values – features connected to the structure of the house interpreted as a feasting hall do not show traces of being burned! However, as you can see, two features deviate from the general MS pattern and can be seen affected by fire and at least in case of one of these features, I do wonder if it represents the bottom of a hearth? These and LOI values will be interesting to relate to plant macrofossile analysis results when I get hold on that report as well.

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