What are Cross Dykes?

Cross dykes are substantial elongated earthworks typically ranging from 0.2 kilometers to 1 kilometer in length, consisting of one or more ditches aligned alongside and parallel to one or more banks.

These features are commonly found in upland areas, traversing ridges and spurs. They are identifiable either as physical earthworks or as patterns discernible in aerial photographs, often combining both forms.

Excavation evidence and comparisons with related historical sites reveal that their construction spans across a millennium, starting from the Middle Bronze Age, and they may have been repurposed in later periods.


Territorial Boundaries?

Based on current knowledge, the prevailing theory suggests that cross ditches served as territorial boundary markers, likely delineating land allocations within communities.

Around 90 instances of such dykes have been documented in England

However, they might have also functioned as pathways, routes for cattle herding, or defensive fortifications.

Cross dykes provide a unique window into how land was divided during prehistoric times, making them invaluable for analyzing settlement patterns and land utilisation during the Bronze Age.

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These ancient features are quite rare today, with very few surviving to the present day. As a result, all well-preserved examples are considered of national significance.

A common cross dykes configuration comprises one or more ditches aligned parallel to one or more raised banks. In the case of a univallate dykes, the ditch typically exhibits a flat-bottomed profile.

On the other hand, multivallate cross dykes feature ditches with a V-shaped cross-sectional structure.

LiDAR shot of a Cross dyke on Compton Down, Dorset.
LiDAR shot of a Cross dyke on Compton Down, Dorset.

A key identifying feature of cross ditches is their orientation, as they traverse the breadth of an upland ridge or the narrow neck of an upland spur.

Cross dykes are typically found at higher altitudes, typically exceeding 150 meters (490 feet) above mean sea level.

Cattle Raids?

Cross dykes were constructed over a span of approximately one thousand years, beginning in the Middle Bronze Age (circa 1500–1000 BC).

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The purpose behind their creation has been a subject of various interpretations, which encompass their potential role as defensive earthworks, pathways for cattle herding, trackways, markers for territorial boundaries, and internal divisions.

Present-day theories tend to favor the latter two functions.

Bank of the univallate of a dyke at Far Black Rigg, Lockton, North Yorkshire
Bank of the univallate cross dyke at Far Black Rigg, Lockton, North Yorkshire

In regions like southern England and southern Scotland, cross dykes are frequently discovered in proximity to hill forts.

These structures, known as cross dykes, acted as control barriers and appear to have been a common response to upland terrain conditions throughout Britain, reflecting similar societal circumstances.

However, in Scotland, these ditches do not seem to have functioned as territorial boundaries, unlike their role in Wessex.

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In certain instances, cross dykes obstructed access to the ridgelines leading to prehistoric settlements such as hill forts.

Since such ditches would not have effectively impeded livestock movement along steeper slopes, it is likely that their primary purpose was to deter human passage.

Chanctonbury Hill, Cross Dyke Once called 'Covered Ways', Cross Dykes run across the ridge of the Downs. This one is some 400 metres West of Chanctonbury Ring where both Roman and prehistoric temples have been excavated.
Chanctonbury Hill, Cross Dyke Once called ‘Covered Ways’, Cross Dykes run across the ridge of the Downs. This one is some 400 metres West of Chanctonbury Ring where both Roman and prehistoric temples have been excavated.

Archaeologist Andrew Fleming has proposed that the cross dykes in Yorkshire could have been monuments dating to the Iron Age (approximately 800 BC to AD 100), potentially serving as deterrents against cattle raids.

Cross Dyke Features

When initially constructed, a univallate cross dyke would typically feature a bare stone bank, often crowned with a palisade, sometimes complemented by the presence of a ditch.

Detailed archaeological investigations have uncovered that these banks were fashioned from rubble, and in some instances, they were further enhanced with stone facing.

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It’s worth noting that some of these banks may have also been surmounted by hedges. Univallate cross dykes, by themselves, did not present a significant obstacle to passage, while multivallate cross ditches were more formidable to traverse.

Cross Dyke near Senghenydd Dyke
Cross Dyke near Senghenydd Dyke

Over time, a cross dyke would have been more substantial in size during their original construction. In regions subject to cultivation, the banks have eroded down to the extent that they have filled the ditches, often leaving only a shallow linear depression in the terrain.

For instance, at East Toft in North Yorkshire, approximately 0.4 kilometers (0.25 miles) of the ditch’s length has vanished entirely due to plowing.

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In contrast, cross dykes situated in moorland areas have typically endured as prominent earthworks, as seen at locations such as Danby Rigg, also in North Yorkshire.

Cross dykes on Heyshott Down, on the South Downs Way near Heyshott, West Sussex.
Cross dykes on Heyshott Down, on the South Downs Way near Heyshott, West Sussex.

In the Cheviot Hills of Scotland, cross ditches generally consist of a single ditch, often flanked by banks on one or both sides.

In cases of bivallate examples, one bank is typically higher than the other.

At Woden Law, five cross ditches were constructed along the ridge, connecting the hill fort with the primary ridgeline of the Cheviots. Subsequently, Roman engineers routed Dere Street across the same land bridge.

How Many Cross Dykes are There?

Around 90 instances of cross dykes have been documented in England, although it’s possible that numerous others have been lost due to plowing or mistakenly categorised as “short linear earthworks.”

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Cross dykes are dispersed across northern and western regions of England, with three primary concentrations found in Yorkshire, Wessex, and an area extending across the Cotswolds and Shropshire.

Cross Dyke, White Sheet Hill, Mere, Wiltshire, England
Cross Dyke, White Sheet Hill, Mere, Wiltshire, England

Notably, cross dykes are a relatively common feature on the South Downs, often intersecting the chalk ridge.

In southeastern Scotland, cross dykes serve as additional defensive elements associated with hill forts situated in the Cheviot Hills. These distinctive features can also be observed in Wales.

Due to their relatively scarce presence today and their significance as indicators of territorial boundaries and land utilisation during the Bronze Age, well-preserved examples of cross ditches of this type are deemed to be of national importance.

Dating Cross Dykes

On the South Downs of southern England, most cross dykes are believed to originate from the late Bronze Age (approximately 1000–700 BC) or the early Iron Age (around 700–400 BC).

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However, a cross dyke that was excavated at Chanctonbury Ring in West Sussex has been confirmed to be of Roman origin, dating from AD 43 to 410. Remarkably, this stands as the sole known cross dyke with such a late date.

Cross Dyke on Fontmell Down
Cross Dyke on Fontmell Down, Dorset

Dating cross dykes has typically relied on their proximity to other nearby monuments, like stone circles and Iron Age field systems, although this dating method lacks absolute certainty.

Some cross dykes may have remained in use through the Middle Ages (AD 410–1485), with a few potentially being constructed during this later period.

Moreover, certain cross dykes have served as boundaries that persisted into modern times, occasionally displaying a close association with parish boundaries.

At the Devil’s Dyke in Sussex, an Iron Age hill fort repurposed an earlier cross dyke as part of its defensive rampart, completely enclosing a second cross dyke.

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Excavations conducted north of Bokerley Dyke in Dorset revealed that these dykes from the Late Iron Age were interpreted by the excavator as settlement boundaries.

The archaeological findings from excavations of cross dykes are relatively limited, typically comprising a small assortment of artifacts such as ceramic fragments, animal bones, and stone tools.

These dykes construction has effectively preserved the ancient land surface, making it a valuable resource for investigation by archaeologists.

In southern Wales, a series of cross dykes that controlled ridgelines around the Rhondda Valley have been dated to the 8th–9th centuries AD, indicating their existence during the Early Middle Ages.