Because of the comparatively few surviving examples and their importance as indicators of territorial boundaries and land use during the Bronze Age, well preserved examples of the type are judged to be of national importance. When built, univallate cross dykes would have consisted of a bare stone bank topped with a palisade, sometimes accompanied by a ditch. Archaeological investigations have revealed that the banks were constructed with rubble; some of them were then faced with stonework. Some of the banks may have been topped by hedges. Univallate cross dykes would not have provided a great obstacle to passage; multivallate cross dykes would have been more formidable to cross. Cross dykes would have been larger when they were first built; in areas subject to cultivation the banks have eroded down to fill the ditches, in may cases leaving just a shallow linear depression in the ground. At East Toft in North Yorkshire, of the dyke's length has completely vanished due to ploughing. Cross dykes situated on moorland often remain as notable earthworks, for example at Danby Rigg, also in North Yorkshire. The Scottish cross dykes in the Cheviot Hills generally consist of a single ditch with a bank on one or both sides. In the bivallate examples, one bank is usually higher than the other. At Woden Law, five cross dykes were built across the ridge linking the hill fort with the main ridgeline of the Cheviots. Roman engineers later ran the course of Dere Street across the same neck of land. On the South Downs of southern England most cross dykes are thought to date to the late Bronze Age (c. 1000 – 700 BC) or early Iron Age (c. 700 – 400 BC) but an excavated cross dyke at Chanctonbury Ring in West Sussex has been proven to be of Roman date (AD 43 – 410). This is the only known cross dyke with such a late date. Cross dykes have tended to be dated by their association with other monuments nearby, such as stone circles and Iron Age field systems, although such dating is not secure. Some cross dykes may have continued in use into the Middle Ages (AD 410 – 1485), with a few possibly being built at this late date. Some cross dykes additionally have functioned as boundaries right through to modern times, and they sometimes exhibit a close relationship with parish boundaries. At the Devil's Dyke in Sussex, an Iron Age hill fort adopted an earlier cross dyke as a portion of its rampart and completely encloses a second cross dyke.