Monday, 20 May 2013

How do I assess thee? Let me count the ways

How do I assess thee? Let me count the ways.
I measure thy depth and breadth and height,
The microscope can reach, those aspects out of sight
Using bright-field and contrast of phase.
I measure to the level of my instrumental ways,
And analytical precision, by plain and cross polarised light.
I count thy inclusions, assessed by eye outright,
I count thy voids, where organics have decayed,
I measure thy referred and related distribution,
Thy particle sorting, if wind or water laid.
I measure all facets of your constitution,
Each of the many layers that amassed.
Revealed, through careful attribution
The hidden secrets of the past.

Friday, 3 May 2013

Multi-tasking in May

My precious
How did it get to be May already? That's 4 months in my new position at Edinburgh! It turns out that having complete responsibility for your own work schedule is liberating but also a challenge. So many tasks, so little time. Starting out on an academic career, I didn't realise how much of my time some of these tasks would take. Even in a research focused position, a great deal of my time over the past 4 months has been spent on administrative duties, including paperwork for teaching a new course next year, coursework and exam marking and moderation, multiple funding applications, and the edited volume of Archaeological and Anthropological Sciences which is slowly taking over my life as the publication date approaches. Not all of these tasks are arduous - there is a strange part of me that gets satisfaction from writing a well constructed argument in a grant proposal (even better when the proposal is successful). Even editorial work is not too bad - the actual process of reading through and making the final tweaks that make a paper polished. The other side of the editorial process however, chasing reviewers, chasing revisions, checking revisions have actually been done, not so much fun.

In amongst that lot, I have even managed to get some research done, thanks largely due to the arrival last month of my new personal microscope, enabling multi-tasking galore at my own desk!  I work much more efficiently jumping between tasks as the inspirations (and deadlines) arise. So having my microscope, computer and library all within reach is rather handy. At the moment I am working on my power point presentation for the 25th Anniversary International Soil Micromorphology Workshop in Cambridge next week. I'm presenting results from a paper recently accepted for publication in Antiquity and co-authored with fellow Catalhoyuk researcher, archaeobotanist and phytolith specialist Phillipa Ryan who works at the British Museum. I'll post further details when it's available online.

Shillito, L-M. and Ryan, P. (in press) Surfaces and streets: phytoliths, micromorphology and changing use of space at Neolithic Çatalhöyük (Turkey) Antiquity

Wednesday, 1 May 2013

Micrograph of the Month: Melted Silica Bubbles

Melted silica in ashy deposits at Neolithic Boncuklu (Turkey) above, and Kamiltepe (Azerbaijan) below.
Silica is one of the most common components of plant ash, and is often seen in the form of phytoliths. In the case studies I have worked on, phytoliths in ash can have >50% abundance in thin section, and there may be millions of them per gram of sediment. Less common are these features, also composed of silica but with a very different appearance. These are 'bubbles' of melted silica, and they occur when silica is present in conjunction with alkali salts. Heating under these conditions causes the silica to melt and form what has been termed a 'glassy slag' or vesicular glass (e.g. see Canti 2003). The word vesicular refers to the gas bubbles you can see within the larger silica mass (also bubble shaped!). I prefer to call it melted silica rather than use the word 'glass' as it can be confusing in an archaeological context. The two examples here are from Boncuklu (above) and Kamiltepe (below), both occupied well before the appearance of glass production. It is quite remarkable that we get these bubbles - pure silica melts around 1600°C, a much higher temperature than could be achieved in these outdoor bonfires we see in the Neolithic. However, the melting point is lowered in the presence of alkali salts, and small pockets within the fire can to a high enough temperature to cause the silica to melt.

Canti, M. 2003. Aspects of the chemical and microscopic characteristics of plant ashes found in archaeological soils CATENA 30: 339-361.