Practical Archaeological Excavation Techniques, day three

October 18th, 2008
post #131   history / prehistory »

My third day on site for the Archaeological Excavation Techniques course.

Afternoon of Saturday18th October 2008. Weather -A sunny afternoon that turned wet and windy.

Today I was to build on the reading I’d done from Philip Barker’s book and the Liverpool Museums site recording guide and begin to put the theory into practice.

I was allocated an area of a trench to examine and record appropriately on context sheets. The sheets form detailed textual descriptions of the contexts (a layer of sand for example, or feature within it) apparent in a trench along with descriptive diagrams.

Today I learned of a new importance for the balks between trenches. In addition to providing safe access (for excavator and the archaeology) across the site, leaving a near complete depth of the trench undisturbed allows features not previously noted (for example, if the weather or daylight precluded them from notice) to remain and be recorded.

In this instance, the trench section had some intrigue - beneath a layer of sandy soil already recorded, lay a circular section of small and larger stones, finer gravels within, surrounded by grey sand. Beneath this, the section had areas of orangey iron panning. These and other features of the trench lead us to believe this is a (MediƦval) ditch - the stones seem to form a line across the site indicating they were posited to allow water flow. The gravels and iron deposits beneath, add to the notion that water once flowed along the lines of stones.

My job was to record in detail on the context sheets a description of each context ( the circular stoney area and its surroundings, and the iron layer beneath). On a third sheet, the ‘cut’ of the section - the perceived edges of the ditch as they’d been originally cut - was to be recorded, although it was thought that this would be done on another day as the feature was difficult to discern.

Before that I had to clean up the section, removing areas that had been slightly weathered by rain by careful removal of material to give a crisp edge that reveals the colour of the earth and aids identification of the different contexts.

The little cleaning I did revealed a second small cluster of gravel adjacent to the larger cluster of stones and an upward curve in the underlying layer that could influence a decision on where the cut of the ditch might lie.

The finer details of the section are difficult to see and require some adjustment of the eye to discern. For this reason repeated discussion of what is apparent in the section can help to determine what features are present. The clear layering of the contexts was disturbed only by runs of light grey sand which are thought to be evidence of animal burrowing. Nevertheless care must be taken to ensure that what the eye sees is not recorded without thought.

The supervisor showed me a drawing of the section I was to further record. These use a 1-to-10 ratio of measurement as opposed to the 1-to-20 ratio used on plan drawings. Recorded in the section drawing were the outlines of the contexts I was to further examine along with outlines for the larger rock features. As with every other aspect of the site, sections have unique numbers of their own for later cross-reference with site, trench, context and find numbers. The drawings also record their orientation so a section may be recorded for all sides of a trench.

I also learned today that another numbering scheme exists for excavation - view numbers - numbers (preceded by a letter ‘V’) given to photographed areas. These are (as ever) retrieved sequentially from pre-printed sheets as required and written on a small blackboard placed in shot.

The recording reference manual contains guidance on the format of all the information that needs to be recorded in each section of the context sheet. The methods range from the ordered to the anecdotal in order to allow as many facets of the context to be recorded, but also allow for quick understanding later on. For example to describe a cut a recorder details a numbered list of predefined features:

  1. Shape in plan
  2. Shape in Section
  3. Dimensions

For a section, these elements are denoted by letters:

  1. Consistency
  2. Texture
  3. Colour
Munsell soil chart  - www.dgcolour.co.uk
An example Munsell Soil Colour chart from dgcolour.co.uk

I was also introduced to Munsell soil colour charts today. A flipbook of punched card pages with printed colour indicators of different soil colours. Each lozenge of colour is bounded by punched holes so that a sample of earth may be dampened and placed on a finger or trowel beneath the page in order to match it to a colour. On the facing page to these punched pages are divided spaces that show the chroma and value definitions (for example 5/4, along with a brief description such as ‘weak red’) for the sample which may then be recorded on the context sheets. Each page has it’s own identifier too - for example 10 YR for a degree of Yellow-Red.

Sadly the weather changed for the worse before I could begin recording and the day’s work was drawn to a premature close.

Before leaving the site I walked towards the farm where the site owners are constructing what will probably be the only Iron Age roundhouses you’ll find (standing!) in this region.

The first is being built to the same dimensions as the roundhouse found in the same field in previous excavations, and will be one of six arranged for the purpose of providing an educative environment for this under-examined period in the North West’s history.

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