So, today is Saturday. That’s just a couple of days away from the arrival of most of the staff and students in Dorstone. What’s going on you ask, if you aren’t all there yet? Well, as with any event, there’s always some last minute things to do. Right now there is someone out shopping for some of those ‘must have’ items for any archaeological excavation and one on our shopping list is string. Lots of string . . . more on that later!
One of the things we’ll be doing on the first morning is marking out the trenches we have opened. This year there are two trenches. The northerly one is 10m x 5m and overlaps one of last year’s trenches, allowing the team to continue excavating one of the mounds. The second trench is a short distance away and will be exploring features revealed by a geophysical survey – more on that in a later blog. This trench is a little larger at 40m x 20m.
Each excavation is laid out on a grid, and over the previous seven seasons of work the team has used the same grid. This is done to enable an accurate plan to be made of all the features and finds made during the lifetime of the project. The way the grid is laid out is fairly simple. There are known points in the field the excavation is taking place in and these have been recorded digitally. Last week as part of our preparations, Liam – a member of the Herefordshire Archaeology team – used some of the latest GPS equipment to locate this year’s trenches to within 3mm on the grid. That’s pretty accurate by anyone’s standards.
The next thing we need to do is to make the grid visible to everyone, and we do this using brightly coloured wooden stakes placed around the edge of each trench, and these will be 5m apart. These are again located used the same GPS system, and are then identified by marking their co-ordinates on them. The co-ordinates tell us how far east and north of our ‘point zero’ each stake is. If you are familiar with reading maps, we’ll be creating our own ‘eastings’ and ‘northings’ These grid points will help us make accurate plans of the trenches before we excavate (known as a ‘pre-ex plan’), and to plan all the features we find.
What about the string? Well, when we get to make detailed drawings of the sections, or trench sides, we’ll need some string. At least 120m of it for the larger of the trenches alone, so it’s never to early to get some!