Cross dyke

A cross dyke or cross-dyke (also referred to as a cross-ridge dyke, covered way, linear ditch, linear earthwork or spur dyke) is a linear earthwork believed to be a prehistoric land boundary that usually measures between 0.2 and 1 kilometre (0.12 and 0.62 mi) in length. A typical cross dyke consists of one or more ditches running in parallel with one or more raised banks.Univallate cross dykes typically have a flat-bottomed ditch while the ditches of multivallate cross dykes possess a V-shaped cross-section. A defining characteristic of a cross dyke is that it cuts across the width of an upland ridge or the neck of an upland spur. Cross dykes generally occur at altitudes over 150 metres (490 ft) above mean sea level.

Cross dykes were built over the course of approximately one thousand years from the Middle Bronze Age (c. 1500–1000 BC) onwards. Interpretations of the reason for their construction vary and include their use as defensive earthworks, cattle droveways, trackways, territorial limits and internal boundaries; current theories favour the latter two uses. In southern England and southern Scotland, cross dykes are often found in association with hill forts. Cross dykes were control barriers that appear to have been a common response to upland conditions across Britain given similar social conditions. In Scotland the dykes do not appear to have served as territorial boundaries as was the case in Wessex. In some cases, cross dykes block the ridgeline approaches to prehistoric settlements such as hill forts. Since such dykes would not have stopped livestock from looping around them on the steeper slopes, such dykes seem designed to block human passage. Archaeologist Andrew Fleming has suggested that the cross dykes of Yorkshire may have been Iron Age (c. 800 BC – AD 100) monuments designed to deter cattle raids.

About 90 examples of cross dykes have been recorded in England, although many more may have been lost to ploughing, or have been wrongly classified as "short linear earthworks". Cross dykes are widely distributed across northern and western England. There are three main concentrations of the features, in Yorkshire, Wessex, and an area spanning the Cotswolds and Shropshire. Cross dykes are a relatively frequent feature on the South Downs, where they frequently cut right across the chalk ridge. In southeastern Scotland, cross dykes are an additional defensive feature associated with hill forts in the Cheviot Hills. Cross dykes are also found in Wales. 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.

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