No thunder or lightning today, just one or two light showers of rain. No sun either and the day was a bit cooler than previous but nonetheless was quite pleasant.
Now with the weather report out of the way we can move on to the work done on site today. In Trench 4 (I always seem to start with this one, possibly because it is the nearest one to the site) Kieran drew a plan of the cutting showing the extent of the ditch, the slopes to the base on each side and the rest of the cutting. This view complements the section he drew yesterday – the section shows the side-view or elevation of all of the layers in the side of the trench while the plan view gives the bird’s-eye-view of the feature excavated. At the same time, I took a series of soil samples from the sides of the trench for magnetic susceptibility analysis. Samples had been taken previously at a higher level and readings have also been taken across the surface of the trench before the trench was desodded so we will end up with a very good record of how magnetic susceptibility varies with depth within the ditch. To remind readers, magnetic susceptibility measures the ability of the soil to become magnetised when a magnetic field is introduced and is a very good indicator of past burning or disposal of organic material like food waste or manure.
Both of these are of course closely related to settlement. The soil samples will have to be processed at a later stage after the excavation is over before the analysis takes place. They will be dried, sieved to remove stones and weighed to produce equal sized samples. In this way, we will be able to get accurate and directly comparable values for magnetic suceptibility. At the end of Kieran’s planning process, the final job to be carried out is to take levels of the area to give an impression of how undulating the planned surface is and to give a feeling for the relative depths of features. This is done on site with a simple dumpy level, which is being used in the photo by Chris who was visiting the site this morning. Chris was one of the geophysics team who first discovered and mapped the enclosure back in 2008 and he was anxious to see for himself how progress was going. In the photo, Kieran is holding the staff, which is like a giant ruler. He places this on each spot in the trench that he wants measured and Chris takes the reading through the level, which is like a small telescope that has been set up on the level. We know the height of the level in space (this has been established already) so we can calculate the heights of each point measured and recorded by Kieran on the plan.
In Trench 1 the work of the past number of days went on and Darren and Matt removed more of the dark, rich organic layer overlying the cobblestones making up the core of the bank. Lots more animal bone was found, some of which seems to have been burned (this will hopefully be confirmed by our animal bone specialist who is visiting next week). Some nice pieces of flint were also found including various flake fragments, a scraper fragment and a complete blade.
Beneath this layer the cobble stones were coming up very nicely and the site in this area at least was beginning to feel more than a little like an early medieval cashel. Because these date to between 500 and 1000AD, I wasn’t too happy with this idea! I still believe the site is Neolithic (4,000 to 2,500BC). I believe the staff have a book open on the date; one bet is that it is 850AD. Traitors! Seriously, no artefacts have been found that suggest that this site is anything other than prehistoric (and probably Neolithic) although, as I said before, some pottery would be very nice and would help remove any doubt. The cobbles in the wall do seem to have collapsed a bit over time; they are most intact at the bank end and less distinct moving eastwards away from the bank. There is also a lot of soil in between them which probably filtered down from above over the years too.
In Trench 1 more progress was made removing one of the ditch fills. Gary and Niamh cleaned up and exposed the layer of stones within this layer and, although at first glance they seem to have a pattern to them and appear to be part of a structure, this is completely coincidental. The excavators are certain that this just happens to be the way the stones settled after rolling or sliding down the slope from above, finally settling at the lowest part of the ditch. We will clean them a bit more and record them in plan anyway, just to be sure.
Spent the morning assembling a sieve for use on the excavation which starts on Monday. It is a sieve with a 5mm mesh, essential for recovering the smaller pieces of flint from the ploughsoil and other contexts.
The design is ingenious and is based on a ‘rocker’ mechanism. The sieve mesh is mounted in a frame where the long sides have gently curving lower edges (a bit like a sleigh). This unit sits into a table-like frame on legs. The sieve can then be easily rocked from one or both ends, taking some of the effort out of the process. I look forward to testing it out, it should help to boost our finds tally.
I think a similar design was used on the Bective Excavations Project last year – so they have no unfair advantage! Thanks to Liam for developing the sieve from ‘concept’ stage to a working reality!
We will also be using another sieve (we will be opening more than one trench) which will be based on a more conventional ‘suspended’ design. Big thanks to Emmet for designing, constructing and delivering that one. It will be interesting to compare performance of the two.
Below is a small selection of the artefacts found during the Brú na Bóinne Fieldwalking Project. In places where there has been prehistoric activity, the stone tools used by our ancestors often survive in the soil. Each year when a field is ploughed, some of these artefacts are turned to the surface and can be collected by archaeologists using appropriate survey techniques and permissions (from the National Museum of Ireland and landowners). Scatters of such material often indicate where intense activity, residential, agricultural, industrial, took place in the past.
The location of the Rossnaree Enclosure was initially identified as a scatter of flint and stone tools on the surface of a ploughed field. Follow-up survey using various types of geophysical equipment allowed us to look below the level of the ploughsoil and explore the extent, layout and some of the internal detail of this unusual site.