Medieval walls are usually shell walls, where you construct an inner and outer shell of finely fitted masonry while filling the space between them with a jumble of smaller stones and mortar. Usually the facing stones don’t project much into the core. When the wall is allowed to erode, once the cap stones have fallen off, the facing starts to peel from the core one ashlar or brick at a time from the top down. Before the resulting rubble layer’s top (rising) reaches the level of the wall’s eroding top (descending), halting erosion, you’ll see a ruinous wall that is thick and smooth-faced in its lower parts and thin and random-looking at the top, because up there only the wall core survives. And at the bottom of the thinner part, there’s a shelf on the topmost surviving facing stones.
In trench A we’re trying to find the northern tower’s outer wall face. The wall seems to be in really poor shape though. All the facing ashlar we find are in an inclined secondary position in the rubble scree, and we haven’t even found any solid wall core, just stones with the mortar still sticking to them in great clumps. We currently believe that any surviving wall facing is likely to be very far down the wall under a lot of rubble, possibly making it uneconomical and chancy to seek it with only seven fieldwork days left. I’m optimistic though that we may still find solid uneroded wall core in there before we give up the attempt. We’ve found no brick here.
Trench B, on flat ground, has given us a surprise. Instead of a rubble cover on and around the base of the torn-down perimeter wall, the trench is a deep solid mass of large ice-ground rounded stones with a lot of air pockets between them, and soil with a lot of bones: cow, sheep/goat, pig and fish. Few stones are dressed, none have the characteristic white coating of stones that have eroded out of a wall, and there is very little mortar or brick fragments in the trench. I really don’t know what to make of this. It’s not rubble. And if the material was put there to level the ground, why use big stones? Is it surplus building material, transported to site and never used? We’ll go down through it until either the stone layer gives out or the trench becomes too cramped for us to be able to go on. It’s only 1.5 m wide at turf level.
Our landlord Niclas has kindly lent us a pulley. We spent the afternoon learning to use it, dragging a great big gneiss block out of trench C and onto the nearby turf. It’s magic!