- Cut into
- The rock of the mound
- Width
- 8–9 metres
- Depth
- 7 metres
- Crossed by
- A stair on an arch, and a timber bridge
A ditch was cut into the living rock all the way round the mound, separating the castle's rock from the plateau it would otherwise have been joined to. Published figures put it at eight to nine metres wide and seven metres deep.
Cutting a ditch is slower and more expensive than raising a wall, and it is worth it, because a wall can be undermined and a ditch cannot. It also gives you the stone you then build with — the quarry and the defence are the same operation.
What the ditch does to an attacker is simple. It stops siege engines and towers getting close enough to matter, and it means that everything approaching the gate has to funnel to one place: the point where the stair crosses.