Wednesday, May 23, 2012

0094 – The irregularity of ditches.

The inner ditch of the enclosure in excavation process: 1,5m deep in first plan survey (back of the dich); 1,3m deep in the next one; 0,8 at the gate. Notice the presence of a layer of geological material at middle depth.

The irregularity of ditches, not in plan, but in depth, is another issue that is very important to question functionality and meaning.

It is expectable that a ditch to accomplish the function of defence or infrastructure of a palisade presents a general regularity in terms of depth. The problem is that for almost all Portuguese ditched enclosures only small parts of ditches were surveyed. But recently to exceptions to this “rule” allow treating this problem.

At Senhora da Alegria, a small enclosure (about 10 meters diameter) at the top of the site presented a circular plan with one gate and only a pit inside. The pit had inside large fragments of burned wood and the ditch revealed a interesting depth profile: it grows deeper from the back towards the gate, with a significant slide percentage.

At the enclosure in process of excavation in Alentejo the inside ditch presents a similar size and also just one gate. But the depth of the ditch reveals the opposite behaviour: it grows deeper from the gate sides to the back: 0.8 / 0.4 at both sides of the gate and 1,5 at the back of the circle. So it presents also a significant slide. Inside, also just one pit, still in excavation (sealed with stones and with complete pots underneath).

What the strange behaviour of the depth of these ditches suggests is that they cannot be associated to any kind of palisade or regular barrier: were they built to be walked inside, from the surface to a deeper area? It has something to do with water circulation and accumulation in a specific area of the ditch? I recall that at least one of the ditches of the enclosure of Águas Frias the structure also ended in a sort of ramp. Let us see what this new enclosure has to reveal in the next days. For the moment the fillings of the ditches are as heterogeneous as their depths.

The back of the ditch: note the absence of geological material layer just one meter away from the other profile.

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