An introduction to soil micromophology

Regular readers of the blog will recognise the name of Dr Jo McKenzie.

And this week, Jo will give a talk in Kirkwall on her work at the Ness and the significance of micromorphology in the ongoing investigations of the Neolithic complex.

Jo is a geoarchaeologist, which means she uses a range of archaeological science techniques to look at archaeological soils and sediments. This season, Jo is looking after Structure Ten but is perhaps best known for her work on soil micromorphology.

Small blocks of undisturbed material are carefully collected so that the structure of the archaeology is preserved. From these, a microscope slide showing a complete “slice” through the sampled deposits can be made.

Small bulk samples collected alongside the tin or block of soil provide material for complementary analyses such as organic matter content, magnetic susceptibility or phosphates, which can often help characterise what we think the soil ‘thin section’ tells us under the microscope.

Soil micromorphology is a powerful technique in archaeology, and it’s particularly useful in understanding areas associated with intensive use, such as hearths or floor surfaces.

Firstly, it allows us to see features too small to be clearly identified, or sometimes seen at all on site.

Did the people of Ness use peat, wood, or maybe turf for their fires?

How many individual burning episodes do we think we can see in the amazing sequences of burnt deposits within the hearths?  And how many under the microscope? 

How hot did these fires get?

Can we identify domestic or industrial activities?

What materials make up the different floor surfaces within the buildings?

Can we match similar floor ‘types’ across the site, and within different buildings?

Can the mineralogy of these surfaces tell us anything about where their materials came from?

What microscopic environmental features were trampled into that surface and what can they tell us about its use?

Secondly, because it uses undisturbed samples, micromorphology allows us to see the exact position of microscopic features within a deposit, and this can give us a really detailed picture of activity as well as identifying archaeological events that can’t be seen with the naked eye.

Jo’s talk takes place in the St Magnus Centre, Kirkwall, on Thursday evening, July 25, at 7.30pm.