The monument, which falls into two areas, includes an Anglo-Saxon frontier work known as Faesten Dic, or `The Strong Dyke', which runs across a now wooded area of undulating sandy gravel situated on the south eastern slope of the Cray valley. The dyke, which survives as a roughly north-south aligned, linear earthwork, takes the form of a series of connected, zigzagging ditches and banks with a total length of c.1.67km. The most heavily defended sections lie on the higher ground towards the southern and northern ends of the monument and comprise a large, originally V-shaped ditch up to 8m wide. This has become partially infilled over the years, but remains visible to a depth of up to 2m in places. The ditch is flanked to the east by a low bank up to c.10.5m wide and c.0.5m high, and to the west by a slight counterscarp bank around 3.5m high and c.0.4m wide. Around 720m from its southern end, the dyke dips down into a steep narrow valley, across which the earthworks take the form of a low bank, interpreted as the original site of a fence or hedge, c.1.5m wide and 0.2m high. At a point around 270m from the northern end of the monument, the dyke zigzags sharply to the south east and north east, and the earthworks here survive as a large bank c.2.5m wide and up to 1.5m high, the form of which has been partially modified over the years by subsequent agricultural activity. No ditch is visible in this area. The dyke has also been partially disturbed in places by the construction of later tracks and woodland boundary banks. The earthworks originally continued to the north east beyond the present bounds of Joydens Wood, but this section has been destroyed by modern development and cultivation. Faesten Dic is thought to have been constructed between the fifth and sixth centuries AD during which time the Anglo-Saxon Chronicle records tribal warfare in the Bexley area. The dyke is also mentioned in an Anglo-Saxon boundary survey of AD 814. Partial excavation in 1941 revealed the existence of a narrow, buried layer of gravel immediately to the east of the bank, interpreted as an associated military walkway. The surfaces of all metalled tracks, and the modern fences which cross the monument are excluded from the scheduling, although the ground beneath these features is included. ASSESSMENT OF IMPORTANCE A small number of substantial and defensible boundary features have been identified as frontier works marking territories in the early medieval period. Up to 50 examples are known with a fairly wide distribution across England, including examples in southern England, East Anglia, Yorkshire, Derbyshire and along the Welsh border. Identified remains extend over distances from as little as 300m up to as much as 240km in the case of Offa's Dyke. They survive in the form of earthworks and as buried features visible as cropmarks or soilmarks on aerial photographs. They appear often to have been constructed across the natural grain of the landscape and, although many examples consisted of a single bank and flanking ditch, to vary considerably in their form and dimensions, even along different stretches of the same boundary, depending upon local topography. Evidence from contemporary documentary sources, excavation and survey suggests that they were constructed in the early medieval period between the fifth and eighth centuries AD. Some were relatively ephemeral, perhaps in use for only a few years during periods of local strife; others, such as Offa's Dyke, constructed between Wales and Mercia, have formed long-lived territorial and/or military boundaries in use for several centuries. As a rare monument type of considerable importance to the study of early medieval territorial patterns, all surviving examples are identified as nationally important. Although it has been partially disturbed by tree roots and subsequent agricultural and forestry activity, the medieval frontier work in Joydens Wood survives well as a substantial, visually impressive landscape feature. Partial excavation has confirmed the survival of archaeological remains and environmental evidence relating to the monument and the landscape in which it was constructed.